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| author | Klaus Thoden <kthoden@mpiwg-berlin.mpg.de> |
|---|---|
| date | Thu, 02 May 2013 11:08:12 +0200 |
| parents | 22d6a63640c6 |
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<?xml version="1.0"?> <archimedes xmlns:xlink="http://www.w3.org/1999/xlink" > <info> <author>Boyle, Robert</author> <title>New experiments physico-mechanicall, touching the spring of the air and its effects</title> <date>1660</date> <place>Oxford</place> <translator></translator> <lang>en</lang> <cvs_file>boyle_exper_013_en_1660.xml</cvs_file> <cvs_version></cvs_version> <locator>013.xml</locator> </info> <text> <front> </front> <body> <chap> <pb xlink:href="013/01/001.jpg"></pb><p type="main"> <s><emph type="center"></emph>NEW <lb></lb><emph type="italics"></emph>EXPERIMENTS <lb></lb>Phyſico-Mechanicall <lb></lb>Touching the Air.<emph.end type="italics"></emph.end><emph.end type="center"></emph.end></s></p><pb xlink:href="013/01/002.jpg"></pb><pb xlink:href="013/01/003.jpg"></pb><p type="main"> <s><emph type="center"></emph>NEW <lb></lb>EXPERIMENTS <lb></lb><emph type="italics"></emph>Phyſico-Mechanicall,<emph.end type="italics"></emph.end><lb></lb>Touching<emph.end type="center"></emph.end></s></p><p type="main"> <s><emph type="center"></emph>The SPRING of the AIR, <lb></lb>and its EFFECTS, <lb></lb>(Made, for the moſt part, in a New <lb></lb><emph type="italics"></emph>PNEuMATICAL ENGINE<emph.end type="italics"></emph.end>)<emph.end type="center"></emph.end></s></p><p type="main"> <s><emph type="center"></emph>Written by way of LETTER<emph.end type="center"></emph.end></s></p><p type="main"> <s><emph type="center"></emph>To the Right Honorable <emph type="italics"></emph>Charles<emph.end type="italics"></emph.end><lb></lb>Lord Vicount of <emph type="italics"></emph>Dungarvan,<emph.end type="italics"></emph.end><lb></lb>Eldeſt Son to the EARL of <emph type="italics"></emph>CORKE.<emph.end type="italics"></emph.end><emph.end type="center"></emph.end></s></p><p type="main"> <s><emph type="center"></emph>By the Honorable <emph type="italics"></emph>Robert Boyle<emph.end type="italics"></emph.end> <expan abbr="Eſq;">Eſque</expan><emph.end type="center"></emph.end></s></p><figure id="id.013.01.003.1.jpg" xlink:href="013/01/003/1.jpg"></figure><p type="main"> <s><emph type="center"></emph><emph type="italics"></emph>OXFORD:<emph.end type="italics"></emph.end><lb></lb>Printed by <emph type="italics"></emph>H: Hall,<emph.end type="italics"></emph.end> Printer to the Univerſity, <lb></lb>for <emph type="italics"></emph>The: Robinſon.<emph.end type="italics"></emph.end> 1660.<emph.end type="center"></emph.end></s></p><pb xlink:href="013/01/004.jpg"></pb><pb xlink:href="013/01/005.jpg"></pb><figure id="id.013.01.005.1.jpg" xlink:href="013/01/005/1.jpg"></figure><p type="main"> <s><emph type="center"></emph>To the Reader.<emph.end type="center"></emph.end></s></p><p type="main"> <s><emph type="italics"></emph>ALthough the following Trea<lb></lb>tiſe being far more prolix <lb></lb>then becomes a Letter, and <lb></lb>then I at firſt intended it; I <lb></lb>am very unwilling to en<lb></lb>creaſe the already exceſsive bulk of the <lb></lb>Book by a Preface, yet there are ſome par<lb></lb>ticulars that I think my ſelf oblig'd to take <lb></lb>notice of to the Reader, as things, that will <lb></lb>either concern him to know, or me to have <lb></lb>known.<emph.end type="italics"></emph.end></s></p><p type="main"> <s><emph type="italics"></emph>In the firſt place then: If it be demand<lb></lb>ed why I publiſh to the World a Letter, which <lb></lb>by its Stile and diverſe Paſſages, appears <lb></lb>to have been written as well For, as To a <lb></lb>particular Perſon; I have chiefly theſe two <lb></lb>things to anſwer: The one, That the Ex<lb></lb>periments therein related, having been ma<lb></lb>ny of them try'd in the preſence of Ingeni<lb></lb>ous Men; and by that means having made<emph.end type="italics"></emph.end><pb xlink:href="013/01/006.jpg"></pb><emph type="italics"></emph>ſome noiſe among the<emph.end type="italics"></emph.end> Virtuoſi (<emph type="italics"></emph>inſomuch <lb></lb>that ſome of them have been ſent into Fo<lb></lb>reign Countries, where they have had the <lb></lb>luck not to be deſpiſ'd) I could not without <lb></lb>quite tyring more then one<emph.end type="italics"></emph.end> Amanuenſis, <emph type="italics"></emph>give <lb></lb>out half as many Copies of them as were ſo <lb></lb>earneſtly deſired, that I could not civilly <lb></lb>refuſe them. </s> <s>The other, That intelligent <lb></lb>Perſons in matters of this kinde perſwaded <lb></lb>me, that the publication of what I had ob<lb></lb>ſerv'd touching the Nature of the Air, <lb></lb>would not be uſeleſs to the World; and that <lb></lb>in an Age ſo taken with Novelties as is ours, <lb></lb>theſe new Experiments would be grateful to <lb></lb>the Lovers of free and real Learning: So <lb></lb>that I might at once comply with my grand <lb></lb>Deſign of promoting Experimental and <lb></lb>Uſeful Philoſophy, and obtain the great ſa<lb></lb>tisfaction of giving ſome to ingenious Men; <lb></lb>the hope of which, is, I confeſs, a tempta<lb></lb>tion that I cannot caſily reſiſt.<emph.end type="italics"></emph.end></s></p><p type="main"> <s><emph type="italics"></emph>Of my being ſomewhat prolix in many <lb></lb>of my Experiments, I have theſe Reaſons <lb></lb>to render, That ſome of them being altoge<lb></lb>ther new, ſeem'd to need the being circum<lb></lb>ſtantially related, to keep the Reader from <lb></lb>diſtruſting them: That divers Circum<lb></lb>ſtances I did here and there ſet down for fear <lb></lb>of forgetting them, when I may hereafter<emph.end type="italics"></emph.end><pb xlink:href="013/01/007.jpg"></pb><emph type="italics"></emph>have occaſion to make uſe of them in my o<lb></lb>ther Writings: That in divers caſes I <lb></lb>thought it neceſſary to deliver things cir<lb></lb>cumſtantially, that the Perſon I addreſſed <lb></lb>them to, might without miſtake, and with <lb></lb>as little trouble as is poſsible, be able to re<lb></lb>peat ſuch unuſual Experiments: and that <lb></lb>after I conſented to let my Obſervations be <lb></lb>made publick, the moſt ordinary Reaſon of <lb></lb>my prolixity was, That foreſeeing that ſuch <lb></lb>a trouble as I met with in making thoſe try<lb></lb>als carefully, and the great expence of time <lb></lb>that they neceſſarily require, (not to mention <lb></lb>the charges of making the Engine, and im<lb></lb>ploying a man to manage it) will probably <lb></lb>keep moſt men from trying again theſe Ex<lb></lb>periments; I thought I might doe the gene<lb></lb>rality of my Readers no unacceptable pe<gap></gap>ce <lb></lb>of ſervice, by ſo punctually relating what <lb></lb>I carefully obſerv'd, that they may look up<lb></lb>on theſe Narratives as ſtanding Records in <lb></lb>our new Pneumaticks, and need not reite<lb></lb>rate themſelves an Experiment to have as <lb></lb>diſtinct an Idea of it, as may ſuffice them <lb></lb>to ground their Reflections and Speculations <lb></lb>upon.<emph.end type="italics"></emph.end></s></p><p type="main"> <s><emph type="italics"></emph>And becauſe ſometimes 'tis the Diſcourſe <lb></lb>made upon the Experiment that makes it <lb></lb>appear prolix, I have commonly left a con-<emph.end type="italics"></emph.end><pb xlink:href="013/01/008.jpg"></pb><emph type="italics"></emph>ſpicuous interval betwixt ſuch Diſcourſes, <lb></lb>and the Experiments whereunto they belong, <lb></lb>or are annexed; that they who deſire onely <lb></lb>the Hiſtorical part of the account we give <lb></lb>of our Engine, may read the Narra<lb></lb>tives, without being put to the trouble <lb></lb>of reading the Reflections too: Which I <lb></lb>here take notice of, for the ſake of thoſe <lb></lb>that are well verſ'd in the New Philoſophy, <lb></lb>and in the Mathematicks; that ſuch <lb></lb>may skip what was deſign'd, but for ſuch <lb></lb>Perſons as may be leſs acquainted even then <lb></lb>I, with matters of this nature (ſcarce ſo <lb></lb>much as mention'd by any Writer in our <lb></lb>Language) and not for them from whom <lb></lb>I ſhall be much more forward to learn, then <lb></lb>to pretend to teach them. </s> <s>Of my being <lb></lb>wont to ſpeak rather doubtfully, or heſitant<lb></lb>ly, then reſolvedly, concerning matters <lb></lb>wherein I apprehend ſome difficulty, I have <lb></lb>in another Treatiſe (which may, through <lb></lb>Gods Aſsiſtance, come abroad ere long) <lb></lb>given a particular, and I hope a ſatisfacto<lb></lb>ry account: Wherefore I ſhall now defend <lb></lb>my Practice but by the Obſervation of<emph.end type="italics"></emph.end> Ari<lb></lb>ſtotle, <emph type="italics"></emph>who ſomewhere notes, That to ſeem <lb></lb>to know all things certainly, and to ſpeak <lb></lb>poſitively of them, is a trick of bold and <lb></lb>yong Fellows: Whereas thoſe that are in-<emph.end type="italics"></emph.end><pb xlink:href="013/01/009.jpg"></pb><emph type="italics"></emph>deed intelligent and conſiderate, are wont to <lb></lb>imploy more wary and diffident Expreſsi<lb></lb>ons, or (as he ſpeaks)<emph.end type="italics"></emph.end> <foreign lang="grc"><gap></gap>σιφέαδ<gap></gap> ἀεὶ τὸ <gap></gap>ς, <lb></lb><gap></gap> τὸ τὰχα. </foreign></s></p><p type="main"> <s><emph type="italics"></emph>There are divers Reflections, and other <lb></lb>Paſſages in the following Epiſtle, and even <lb></lb>ſome Experiments (occaſionally mention'd) <lb></lb>which may ſeem either impertinent or ſu<lb></lb>perfluous, but are not ſo: Being purpoſely <lb></lb>written, either to evince ſome truth oppoſ'd, <lb></lb>or diſprove ſome erroneous conceit main<lb></lb>tain'd, by ſome eminent New Philoſopher, <lb></lb>or by ſome other Ingenious Men, who, I <lb></lb>preſum'd, would eaſily forgive me the ha<lb></lb>ving on ſuch occaſions purpoſely omitted <lb></lb>their Names; though an inquiſitive Perſon <lb></lb>will probably diſcover divers of them, by <lb></lb>the mention of the Opinions diſprov'd in <lb></lb>the Experiments I am excuſing.<emph.end type="italics"></emph.end></s></p><p type="main"> <s><emph type="italics"></emph>Ever ſince I diſcern'd the uſefulneſs <lb></lb>of ſpeculative Geometry to Natural Phi<lb></lb>loſophy, the unhappy Diſtempers of my Eyes, <lb></lb>have ſo far kept me from being much con<lb></lb>verſant in it, that I fear I ſhall need the par<lb></lb>doz of my Mathematical Readers, for ſome <lb></lb>Paſſages, which if I had been deeply skill'd <lb></lb>in Geometry, I ſhould have treated more ac<lb></lb>curately.<emph.end type="italics"></emph.end></s></p><pb xlink:href="013/01/010.jpg"></pb><p type="main"> <s><emph type="italics"></emph>And indeed, having, for Reaſons elſe<lb></lb>where deduc'd, purpoſely kept my ſelf a <lb></lb>ſtranger to moſt of the new<emph.end type="italics"></emph.end> Hypotheſes <emph type="italics"></emph>in <lb></lb>Philoſophy, I am ſenſible enough that the <lb></lb>Engine I treat of has prevail'd with me to <lb></lb>write of ſome ſubjects which are ſufficient<lb></lb>ly remote from thoſe I have been moſt con<lb></lb>verſant in. </s> <s>And having been reduc'd to <lb></lb>write the greateſt part of the enſuing Letter <lb></lb>at a diſtance, not onely from my Library, <lb></lb>but from my own Manuſcripts, I cannot <lb></lb>but fear that my Diſcourſes do not onely <lb></lb>want many choice things wherewith the <lb></lb>Learned Writings of others might have en<lb></lb>riched or imbelliſhed them: But that partly <lb></lb>for this Reaſon, and partly for that touch'd <lb></lb>upon a little before, It is poſsible I may <lb></lb>have mention'd ſome Notions already pub<lb></lb>liſh'd by others, without taking notice of the <lb></lb>Authors, not out of any deſign to defraud <lb></lb>deſerving Men, but for want of knowing <lb></lb>ſuch particulars to have been already pub<lb></lb>liſh'd by them: Eſpecially the Experiments <lb></lb>of our Engine being themſelves ſufficient <lb></lb>to hint ſuch Notions as we build upon <lb></lb>them.<emph.end type="italics"></emph.end></s></p><p type="main"> <s><emph type="italics"></emph>The order of the Experiments every <lb></lb>Reader may alter, as ſuits beſt with his own <lb></lb>Deſign in peruſing them; For not onely all<emph.end type="italics"></emph.end><pb xlink:href="013/01/011.jpg"></pb><emph type="italics"></emph>thoſe betwixt whom there is an Affinity in <lb></lb>Nature (by belonging to one ſubject) are not <lb></lb>always plac'd one by another, but they are <lb></lb>not ſtill ſet down ſo much as in the order <lb></lb>wherein they were made; but moſt common<lb></lb>ly in that caſual one wherein my occaſions in<lb></lb>duc'd me to diſpatch them to the Preſs. </s> <s>And, <lb></lb>which is worſe, I did uſually ſend quite a<lb></lb>way the former Experiments, before the <lb></lb>later were written, or perhaps ſo much as <lb></lb>made: Whereby I loſt the advantage of cor<lb></lb>recting and ſupplying the Imperfections of <lb></lb>what I had formerly written, by the light of <lb></lb>my ſubſequent Tryals and Diſcoveries.<emph.end type="italics"></emph.end></s></p><p type="main"> <s><emph type="italics"></emph>Beſides all this, the diſtemper in my eyes <lb></lb>forbidding me not onely to write my ſelf ſo <lb></lb>much as one Experiment, but even to read <lb></lb>over my ſelf what I dictated to others. </s> <s>I can<lb></lb>not but fear, that beſides the Authors miſtakes, <lb></lb>this Edition may be blemiſh'd by many, that <lb></lb>may be properly imputed to a very unskil<lb></lb>ful Writer (whom I was often times by haſte <lb></lb>reduc'd againſt my cuſtom to imploy) and <lb></lb>may have eſcaped the Diligence of that <lb></lb>Learned Friend, that does me the favor to <lb></lb>over-ſee the Preſs; eſpecially there being <lb></lb>the diſtance of two days Fourney betwixt it <lb></lb>and me.<emph.end type="italics"></emph.end></s></p><p type="main"> <s><emph type="italics"></emph>I need not perhaps repreſent to the equi-<emph.end type="italics"></emph.end><pb xlink:href="013/01/012.jpg"></pb><emph type="italics"></emph>table Reader, how much the ſtrange Confu<lb></lb>ſions of this unhappy Nation, in the midſt <lb></lb>of which I have made and written theſe <lb></lb>Experiments, are apt to diſturb that calm<lb></lb>neſs of Minde, and undiſtractedncſs of <lb></lb>Thoughts, that are wont to be requiſite to <lb></lb>Happy Speculations. </s> <s>But I preſume, <lb></lb>that by all theſe things put together, he <lb></lb>will readily perceive, That I have been <lb></lb>ſo far from following the Poets prudent <lb></lb>Counſel touching the ſlow Publication of <lb></lb>Books deſign'd to purchaſe credit by,<emph.end type="italics"></emph.end></s></p><p type="main"> <s>—— Nonumque prematur in Annum </s></p><p type="main"> <s><emph type="italics"></emph>that I ſuffer this Treatiſe to come abroad <lb></lb>into the World with a multitude of Diſad<lb></lb>vantages.<emph.end type="italics"></emph.end></s></p><p type="main"> <s><emph type="italics"></emph>But if it be demanded, why then I did <lb></lb>not make it fitter for the Preſs before I ſent <lb></lb>it thither? </s> <s>my Anſwer muſt be, That not <lb></lb>at firſt imagining that this ſort of Experi<lb></lb>ments would prove any thing near ſo trouble<lb></lb>ſome, either to make, or to Record, as I <lb></lb>afterwards found them, I did, to engage <lb></lb>the Printer to diſpatch, promiſe him to ſend <lb></lb>him the whole Epiſtle in a very ſhort time: <lb></lb>So that although now and then the occaſional <lb></lb>vacations of the Preſs, by reaſon of Feſti-<emph.end type="italics"></emph.end><pb xlink:href="013/01/013.jpg"></pb><emph type="italics"></emph>vals, or the abſence of the Corrector, gave <lb></lb>me the leiſure to exſpaciate upon ſome ſub<lb></lb>ject; yet being oftentimes call'd upon to diſ<lb></lb>patch the Papers to the Preſs, my promiſe, <lb></lb>and many unexpected Avocations, obliged <lb></lb>me to a haſte, which, though it have detract<lb></lb>ed nothing from the Faithfulneſs of the <lb></lb>Hiſtorical part of our Book, has (I fear) <lb></lb>been diſadvantageous enough to all the reſt. <lb></lb></s> <s>And I made the leſs ſcruple to let the fol<lb></lb>lowing Papers paſs out of my hands, with <lb></lb>all their Imperfections; becauſe, as the <lb></lb>publick Affairs, and my own, were then <lb></lb>circumſtanc'd, I knew not when (if at all) <lb></lb>I ſhould be again in a condition to proſecute <lb></lb>Experiments of this kinde; eſpecially, <lb></lb>ſince (to omit my being almoſt weary of be<lb></lb>ing, as it were, confin'd to one ſort of Ex<lb></lb>periments) I am pre-ingag'd (if it pleaſe <lb></lb>God to vouchſafe me Life and Health) to <lb></lb>imploy my firſt leiſure in the publication of <lb></lb>ſome other Phyſiological Papers, which I <lb></lb>thought 'twould make me much the ſitter to <lb></lb>take in hand, if I firſt diſpatch'd all that <lb></lb>I had at this time to write touching our <lb></lb>Engine.<emph.end type="italics"></emph.end></s></p><p type="main"> <s><emph type="italics"></emph>I have this further to adde, by way <lb></lb>of Excuſe, That as it has been my deſign <lb></lb>in publiſhing theſe Experiments to gratifie<emph.end type="italics"></emph.end><pb xlink:href="013/01/014.jpg"></pb><emph type="italics"></emph>Ingenious men; ſo, if I have not been <lb></lb>much flattered, I may hope that the vari<lb></lb>ous hints to be met with in the following <lb></lb>Letter, will (at leaſt) ſomewhat awaken <lb></lb>mens thoughts, & excite them to new ſpecula<lb></lb>tions (ſuch as perhaps even inquiſitive men <lb></lb>would ſcarce elſe light upon) and I need not <lb></lb>deſpair, that even the examination of ſuch <lb></lb>new Suſpicions and Enquiries will hence al<lb></lb>ſo, at leaſt Occaſionally be facilitated: I <lb></lb>ſaid Occaſionally, becauſe it being, as 'tis <lb></lb>proverbially ſaid,<emph.end type="italics"></emph.end> Facile Inventis addere. <lb></lb><emph type="italics"></emph>It ſeems not irrational to expect, that our <lb></lb>Engine it ſelf, and divers of our Experi<lb></lb>ments, will be much promoted by the Indu<lb></lb>ſtry of Inventive and Mathematical Wits, <lb></lb>whoſe contrivances may eaſily either correct <lb></lb>or ſupply, and conſequently ſurpaſs many of <lb></lb>thoſe we have made uſe of. </s> <s>And, particu<lb></lb>larly, if Men by skill and patience can ar<lb></lb>rive both to evacuate ſuch Receivers as <lb></lb>ours, till there be no more Air left in them, <lb></lb>then there ſeems to have remain'd in the <lb></lb>Glaſſes made uſe of about the Magdebur<lb></lb>gick Experiment (hereafter to be mention<lb></lb>ed) and to keep out the Air for a competent <lb></lb>while, the Uſefulneſs and Diſcoveries of our <lb></lb>Engine, will not be a little advanc'd. </s> <s>And <lb></lb>perhaps that may belong to it, which I re-<emph.end type="italics"></emph.end><pb xlink:href="013/01/015.jpg"></pb><emph type="italics"></emph>member<emph.end type="italics"></emph.end> Seneca <emph type="italics"></emph>ſpeaks of Nature,<emph.end type="italics"></emph.end> Initia<lb></lb>tos (<emph type="italics"></emph>ſays be<emph.end type="italics"></emph.end>) nos credimus, in Veſtibulo <lb></lb>ejus hæremus: <emph type="italics"></emph>For being now in a place <lb></lb>where we are not quite deſtitute of moderate<lb></lb>ly skilful Artificers, we have, ſince the <lb></lb>Concluſion of the following Letter, made <lb></lb>ſome Additions to our Engine, by whoſe help <lb></lb>we finde (upon ſome new tryals) that we <lb></lb>may be able, without much of new trouble, <lb></lb>to keep the ambient Air out of the exhau<lb></lb>ſted Receiver for a whole day; and perhaps <lb></lb>we ſhould be able to keep it out much longer, <lb></lb>if before we ſhall have diſpatch'd ſome ur<lb></lb>gent Affairs, and publiſh'd ſome Papers for <lb></lb>which a kinde of Promiſe is thought to make <lb></lb>us Debtors to the Preſs, we could be at lei<lb></lb>ſure to proſecute ſuch Experiments, as may <lb></lb>poſsibly afford a Supplement to the follow<lb></lb>ing Treatiſe, from which I ſhall now no lon<lb></lb>ger detain the Reader.<emph.end type="italics"></emph.end></s></p><p type="main"> <s><emph type="italics"></emph>I know<emph.end type="italics"></emph.end></s></p><pb xlink:href="013/01/016.jpg"></pb><pb xlink:href="013/01/017.jpg"></pb><figure id="id.013.01.017.1.jpg" xlink:href="013/01/017/1.jpg"></figure><p type="main"> <s>Friendly Reader, </s></p><p type="main"> <s><emph type="italics"></emph>I Know all Perſons <lb></lb>that have a publick <lb></lb>Spirit for the Ad<lb></lb>vancement of Lear<lb></lb>ning, will think much that this <lb></lb>piece came not out in a Lan<lb></lb>guage of more general Uſe, <lb></lb>then this you ſee it now attir'd <lb></lb>in; eſpecially ſince the Excel<lb></lb>lent Noble Perſon, who is the <lb></lb>Author, is known to be well a<lb></lb>ble himſelf (being almoſt uni<lb></lb>verſally a Linguiſt) to have gi<lb></lb>ven it either the Old Latin, or<emph.end type="italics"></emph.end><pb xlink:href="013/01/018.jpg"></pb><emph type="italics"></emph>the newer French Dreſs.<emph.end type="italics"></emph.end></s></p><p type="main"> <s><emph type="italics"></emph>But if it be an Honor to a <lb></lb>Language to be preferr'd, and <lb></lb>this Honor breeds ſometimes an <lb></lb>Emulation, as anciently it did <lb></lb>between the<emph.end type="italics"></emph.end> Greeks <emph type="italics"></emph>and<emph.end type="italics"></emph.end> Ro<lb></lb>mans, <emph type="italics"></emph>it cannot be thought <lb></lb>unhandſome for an Engliſh <lb></lb>Nobleman to have preferr'd <lb></lb>his own: And it may be a ſuf<lb></lb>ficient Reaſon for the Gentry <lb></lb>of Forein Parts to learn our <lb></lb>Speech, or keep Interpreters, <lb></lb>that they are ſure to have for <lb></lb>their requital, from many of <lb></lb>our Engliſh Writers (as here <lb></lb>from this piece) much curiouſly <lb></lb>ingenious, and profitable Lear<lb></lb>ning.<emph.end type="italics"></emph.end></s></p><pb xlink:href="013/01/019.jpg"></pb><p type="main"> <s><emph type="italics"></emph>But as to this particular (give <lb></lb>me leave to uſe Words from a <lb></lb>Story)<emph.end type="italics"></emph.end> Since the Mountain <lb></lb>cannot come to <emph type="italics"></emph>Mahomet, <lb></lb>Mahomet<emph.end type="italics"></emph.end> will go to the <lb></lb>Mountain<emph type="italics"></emph>: I mean thus; <lb></lb>Becauſe many witty Men, Per<lb></lb>ſons of Honor and Eſtate eſpe<lb></lb>cially, may be ſuppoſ'd to be a<lb></lb>ble to make a better account, by <lb></lb>employing their Studies and <lb></lb>Time on Matter then Words, <lb></lb>and ſo are juſtly impeded from <lb></lb>learning Languages; And be<lb></lb>cauſe (as I may judge) the no<lb></lb>ble Author is willing to oblige all <lb></lb>Men, He has already provi<lb></lb>ded, that this piece ſhall ſhort<lb></lb>ly be done into Latine, that ſo<emph.end type="italics"></emph.end><pb xlink:href="013/01/020.jpg"></pb><emph type="italics"></emph>it may come home to divers wor<lb></lb>thy Perſons in its Stream, who <lb></lb>cannot travel to finde it out in <lb></lb>its firſt Origine.<emph.end type="italics"></emph.end></s></p><p type="main"> <s><emph type="italics"></emph>Having therefore leave ſo <lb></lb>to do, I cannot forbear to give <lb></lb>the World the Advertiſement <lb></lb>of this Latine Edition, leſt <lb></lb>ſome skilful Artiſt ſhould take <lb></lb>needleſs pains about a Work, <lb></lb>which will, ere long (by Gods <lb></lb>furtherance) be done to his <lb></lb>Hands; For ſuch unprofitable <lb></lb>expences of Study have too fre<lb></lb>quently happened, and too much <lb></lb>to the diſadvantage of Learn<lb></lb>ing, for want of a ſufficient <lb></lb>Correſpondence and Intercourſe <lb></lb>between ſuch as are exerciſed<emph.end type="italics"></emph.end><pb xlink:href="013/01/021.jpg"></pb><emph type="italics"></emph>in the Mines of Wiſdome.<emph.end type="italics"></emph.end></s></p><p type="main"> <s><emph type="italics"></emph>This is all the trouble I ſhall <lb></lb>at preſent give you: Nor ſhall I <lb></lb>need minde thee, if you have a <lb></lb>true guſt for the Book you read, <lb></lb>to have an honor and thankful <lb></lb>regard to the Perſon that has <lb></lb>favor'd us with the Communi<lb></lb>cation of theſe his Tryals, & is <lb></lb>manifeſtly ſo great a Patron <lb></lb>and Friend to Experimental <lb></lb>Learning, and all true Wiſdom; <lb></lb>for ſhould you fail in this, you <lb></lb>might deſervedly be depriv'd of <lb></lb>ſome other Obſervations on the <lb></lb>ſame ſubject, which the Au<lb></lb>thor, I heare, has made ſince the <lb></lb>finiſhing of this Treatiſe.<emph.end type="italics"></emph.end></s></p><p type="main"> <s><emph type="italics"></emph>I deſire to be excuſed that I<emph.end type="italics"></emph.end><pb xlink:href="013/01/022.jpg"></pb><emph type="italics"></emph>not make Excuſes for the ſlow<lb></lb>neſs of the Publication, hoping <lb></lb>that the long expectation you <lb></lb>have had of it, will enhance, and <lb></lb>not diminiſh your delight in the <lb></lb>enjoyment of a piece like to be, <lb></lb>amongſt the ſtudents in accurate <lb></lb>Philoſophy, of ſo generall accep<lb></lb>tance. </s> <s>Farewel.<emph.end type="italics"></emph.end></s></p><p type="main"> <s>R: Sh. <lb></lb><figure id="id.013.01.022.1.jpg" xlink:href="013/01/022/1.jpg"></figure></s></p><pb xlink:href="013/01/023.jpg"></pb><figure id="id.013.01.023.1.jpg" xlink:href="013/01/023/1.jpg"></figure><p type="main"> <s><emph type="center"></emph>A Summary of the chief Matters treated <lb></lb>of in this Epiſtolical Diſcourſe.<emph.end type="center"></emph.end></s></p><p type="main"> <s><emph type="italics"></emph>THe<emph.end type="italics"></emph.end> Proæmium, <emph type="italics"></emph>wherein is ſet down the <lb></lb>occaſion of this Diſcourſe,<emph.end type="italics"></emph.end> 1. <emph type="italics"></emph>The mo<lb></lb>tives that induc'd the Author thereunto,<emph.end type="italics"></emph.end> 2 &c. <lb></lb><emph type="italics"></emph>The hints he received,<emph.end type="italics"></emph.end> 5. <emph type="italics"></emph>The things where<lb></lb>in this Engine excels any that have yet been <lb></lb>made uſe of,<emph.end type="italics"></emph.end> 6 &c. <emph type="italics"></emph>The deſcription of the <lb></lb>Engine and its parts,<emph.end type="italics"></emph.end> 8 &c. <emph type="italics"></emph>The way of pre<lb></lb>paring and uſing it,<emph.end type="italics"></emph.end> 15 &c. <emph type="italics"></emph>The diviſion of <lb></lb>the Experiments tryable thereby into two <lb></lb>ſorts, and the difficulty of excluding the <lb></lb>Air.<emph.end type="italics"></emph.end> 18 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The firſt Experiment, touching the man<lb></lb>ner of pumping out the Air, and by what de<lb></lb>grees the Receiver is emptyed,<emph.end type="italics"></emph.end> 20, &c. <emph type="italics"></emph>A di<lb></lb>greſsion touching the Spring or Elaſtical <lb></lb>power of the Air, with an attempt for a Me<lb></lb>chanical Explication thereof, neceſſary to be <lb></lb>premiſ'd for the explanation of the<emph.end type="italics"></emph.end> Phæno<lb></lb>mena, <emph type="italics"></emph>exhibited in this and the ſubſequent <lb></lb>Experiments.<emph.end type="italics"></emph.end> 22 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The ſecond Experiment, touching the preſ<lb></lb>ſure of the Air againſt the ſides of the Bodies <lb></lb>it invirons,<emph.end type="italics"></emph.end> 37 &c. <emph type="italics"></emph>with a digreſsive Ex<lb></lb>plication of the preſſure of the Air included <lb></lb>within an ambient Body.<emph.end type="italics"></emph.end> 39 &c. </s></p><pb xlink:href="013/01/024.jpg"></pb><p type="main"> <s><emph type="italics"></emph>The third Experiment, touching the <lb></lb>force requiſite to draw down the Sucker,<emph.end type="italics"></emph.end> 42 <lb></lb>&c. <emph type="italics"></emph>The Opinion of an eminent Modern <lb></lb>Naturaliſt examin'd.<emph.end type="italics"></emph.end> 44 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The fourth Experiment, touching the <lb></lb>ſwelling of a Bladder; with the degrees by <lb></lb>which it increaſes,<emph.end type="italics"></emph.end> 45 &c. <emph type="italics"></emph>Another Opini<lb></lb>on of a Learned Author examin'd.<emph.end type="italics"></emph.end> 48 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The fifth Experiment, touching the break<lb></lb>ing of a Bladder in the Receiver,<emph.end type="italics"></emph.end> 49 &c. <lb></lb><emph type="italics"></emph>And of another by heat.<emph.end type="italics"></emph.end> 52 </s></p><p type="main"> <s><emph type="italics"></emph>The ſixth Experiment, of divers ways by <lb></lb>which the elaſtical expanſion of the Air <lb></lb>was meaſur'd.<emph.end type="italics"></emph.end> 52 &c </s></p><p type="main"> <s><emph type="italics"></emph>The ſeventh Experiment, touching what <lb></lb>Figure does beſt reſiſt the preſſure of the Air.<emph.end type="italics"></emph.end> 62 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The eighth Experiment, tending to a fur<lb></lb>ther Demonſtration of the former, from the <lb></lb>breaking of glaſs a Helmet inward.<emph.end type="italics"></emph.end> 64 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The ninth Experiment, contains a fur<lb></lb>ther confirmation from the breaking of a <lb></lb>Glaſs outward,<emph.end type="italics"></emph.end> 66 &c. <emph type="italics"></emph>with an Experiment to <lb></lb>prove, that theſe<emph.end type="italics"></emph.end> Phænomena <emph type="italics"></emph>proceed not <lb></lb>from an invincible<emph.end type="italics"></emph.end> Fuga vacui 69. <emph type="italics"></emph>A de<lb></lb>ſcription of other ſmall Receivers, and their <lb></lb>Conveniencies,<emph.end type="italics"></emph.end> 70 &c. <emph type="italics"></emph>A Receipt for the <lb></lb>making of a Compoſition to Cement crackt <lb></lb>Glaſſes.<emph.end type="italics"></emph.end> 73 </s></p><pb xlink:href="013/01/025.jpg"></pb><p type="main"> <s><emph type="italics"></emph>The tenth Experiment, touching the fla<lb></lb>ming of Candles incloſed in the Receiver.<emph.end type="italics"></emph.end> 74 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The eleventh Expertment, touching the <lb></lb>burning of Coals,<emph.end type="italics"></emph.end> 78. <emph type="italics"></emph>And the laſting of <lb></lb>the excandeſcence of an included piece of I<lb></lb>ron.<emph.end type="italics"></emph.end> 80. </s></p><p type="main"> <s><emph type="italics"></emph>The twelfth Experiment concerning the <lb></lb>burning of Match.<emph.end type="italics"></emph.end> 82 </s></p><p type="main"> <s><emph type="italics"></emph>The thirteenth Experiment, concerning <lb></lb>the further proſecution of the preceding, <lb></lb>tending to prove the extinction of the Fire <lb></lb>in the former Experiments, not to have <lb></lb>proceeded from the preſſure of the Fire by the <lb></lb>Fumes,<emph.end type="italics"></emph.end> 84. <emph type="italics"></emph>Some remarkable Circumſtan<lb></lb>ces of it,<emph.end type="italics"></emph.end> 86. <emph type="italics"></emph>The Experiment of Match <lb></lb>try'd in a ſmall Receiver.<emph.end type="italics"></emph.end> 87 </s></p><p type="main"> <s><emph type="italics"></emph>The fourteenth Experiment, touching the <lb></lb>ſtriking Fire, and kindling of Powder with <lb></lb>the Lock of a Piſtol in the evacuated Recei<lb></lb>ver.<emph.end type="italics"></emph.end> 88 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The fifteenth Experiment, touching the <lb></lb>unſucceſsfulneſs of kindling included Bo<lb></lb>dies with a burning Glaſs, and the Au<lb></lb>thors intention to proſecute it further.<emph.end type="italics"></emph.end> 102 </s></p><p type="main"> <s><emph type="italics"></emph>The ſixteenth Experiment, concerning the <lb></lb>operation of the Loadſtone.<emph.end type="italics"></emph.end> 105, &c. </s></p><pb xlink:href="013/01/026.jpg"></pb><p type="main"> <s><emph type="italics"></emph>The ſeventeenth Experiment, touching the <lb></lb>gradual deſcent of the Quick-ſilver in the <lb></lb>Torricellian Experiment,<emph.end type="italics"></emph.end> 106 &c. <emph type="italics"></emph>Some <lb></lb>obſervable Circumſtances concerning it,<emph.end type="italics"></emph.end><lb></lb>112 &c. <emph type="italics"></emph>The ſame Experiment try'd in <lb></lb>one of the ſmall Receivers,<emph.end type="italics"></emph.end> 115. <emph type="italics"></emph>How <lb></lb>this Experiment may be made uſe of to know <lb></lb>the ſtrength of the preſſure of the Air for <lb></lb>every degree of Rarefaction,<emph.end type="italics"></emph.end> 116 &c. <emph type="italics"></emph>The <lb></lb>tryal of the ſame Experiment in a Tube not <lb></lb>two foot long,<emph.end type="italics"></emph.end> 118. <emph type="italics"></emph>The raiſing of the Mer<lb></lb>curial Cylinder, by the forcing of more Air <lb></lb>into the Receiver,<emph.end type="italics"></emph.end> 119. <emph type="italics"></emph>Some Allegations <lb></lb>for and againſt a<emph.end type="italics"></emph.end> Vacuum <emph type="italics"></emph>conſider'd,<emph.end type="italics"></emph.end> 120 <lb></lb>&c. <emph type="italics"></emph>Some Advertiſements concerning the <lb></lb>inconveniencies that may ariſe from the di<lb></lb>verſity of meaſures made uſe of for the defi<lb></lb>ning the Altitute of the Mercurial Cylinder; <lb></lb>and from the neglect of little parcels of Air <lb></lb>apt to remain between the Mercury and the <lb></lb>concave ſurface of the Tube,<emph.end type="italics"></emph.end> 123 &c. <emph type="italics"></emph>Some <lb></lb>Expedients for the more exact filling the <lb></lb>Tube,<emph.end type="italics"></emph.end> 127. <emph type="italics"></emph>The height the Author once found <lb></lb>of the Mercurial Cylinder, according to En<lb></lb>gliſh meaſure.<emph.end type="italics"></emph.end> 128. </s></p><p type="main"> <s><emph type="italics"></emph>The eighteenth Experiment, containing <lb></lb>a new Obſervation touching the variation <lb></lb>of the height of the Mercurial Cylinder in <lb></lb>the ſame Tube, with an oſſer at the reaſon<emph.end type="italics"></emph.end><pb xlink:href="013/01/027.jpg"></pb><emph type="italics"></emph>thereof.<emph.end type="italics"></emph.end> 129 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 19<emph type="sup"></emph>th<emph.end type="sup"></emph.end> <emph type="italics"></emph>Experiment, touching the ſub<lb></lb>ſiding of a Cylinder of Water,<emph.end type="italics"></emph.end> 140 &c. <emph type="italics"></emph>The <lb></lb>ſame try'd in a ſmall Receiver.<emph.end type="italics"></emph.end> 143 </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 20<emph type="sup"></emph>th<emph.end type="sup"></emph.end> <emph type="italics"></emph>Experiment, touching the<emph.end type="italics"></emph.end> Ela<lb></lb>ter <emph type="italics"></emph>of Water, with a digreſsive Experiment <lb></lb>to the ſame purpoſe<emph.end type="italics"></emph.end> 144 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 21 <emph type="italics"></emph>Experiment, being a proſecution <lb></lb>of the former Enquiry, by Experimenting <lb></lb>the Generation of Bubbles under Water, a <lb></lb>recital of ſome notable Circumſtances, with <lb></lb>ſome obſervable Corollary's deduc'd there<lb></lb>from.<emph.end type="italics"></emph.end> 147 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 22<emph type="sup"></emph>d<emph.end type="sup"></emph.end> <emph type="italics"></emph>Experiment, tending to a deter<lb></lb>mination of the Enquiry propoſ'd in the for<lb></lb>mer Experiment, by proving the matter of <lb></lb>theſe Bubbles from their permanency to be <lb></lb>Air: The Experiments try'd in the great <lb></lb>and ſmall Receivers, evincing the ſame <lb></lb>thing,<emph.end type="italics"></emph.end> 155 &c. <emph type="italics"></emph>An Experiment wherein <lb></lb>there appear'd Bubbles in Quick-ſilver,<emph.end type="italics"></emph.end><lb></lb>160. <emph type="italics"></emph>The Authors Inference,<emph.end type="italics"></emph.end> 162. <emph type="italics"></emph>A di<lb></lb>greſsive Enquiry, whether or no Air may be <lb></lb>generated anew; with ſeveral Hiſtories and <lb></lb>Experiments, tending to the reſolving and <lb></lb>clearing thereof.<emph.end type="italics"></emph.end> 162 &c <emph type="italics"></emph>The Authors ex<lb></lb>cuſe for ſo long a Digreſsion.<emph.end type="italics"></emph.end> 181 </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 23<emph type="sup"></emph>d<emph.end type="sup"></emph.end> <emph type="italics"></emph>Experiment, containing a fur<lb></lb>ther Enquiry touching Bubbles mad with<emph.end type="italics"></emph.end><pb xlink:href="013/01/028.jpg"></pb><emph type="italics"></emph>common and diſtill'd Water.<emph.end type="italics"></emph.end> 182 </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 24<emph type="sup"></emph>th<emph.end type="sup"></emph.end> <emph type="italics"></emph>Experiment, wherein the inqui<lb></lb>ry is proſecuted with other Liquors, as with <lb></lb>Sallet Oyl, Oyl of Turpentine, a Solution of <lb></lb>Tartar, Spirit of Vinegar, Red-wine, Milk, <lb></lb>Hen's Eggs, Spirit of Urine, Spirit of <lb></lb>Wine and Water, Spirit of Wine.<emph.end type="italics"></emph.end> 187 &c. <lb></lb><emph type="italics"></emph>The wonderful expanſion of the Spirit of <lb></lb>Wine.<emph.end type="italics"></emph.end> 194 </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 25<emph type="sup"></emph>th<emph.end type="sup"></emph.end> <emph type="italics"></emph>Experiment, touching the ex<lb></lb>panſion and gravity of the Air under wa<lb></lb>ter.<emph.end type="italics"></emph.end> 195 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 26<emph type="sup"></emph>th<emph.end type="sup"></emph.end> <emph type="italics"></emph>Experiment, touching the Vi<lb></lb>brations of a<emph.end type="italics"></emph.end> Pendulum. </s> <s>202 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 27<emph type="sup"></emph>th<emph.end type="sup"></emph.end> <emph type="italics"></emph>Experiment, touching the pro<lb></lb>pagation of ſound: And the Authors inten<lb></lb>tion of trying ſome other Experiments, for <lb></lb>the further elucidation thereof.<emph.end type="italics"></emph.end> 210 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 28 <emph type="italics"></emph>Experiment, touching the ſudden <lb></lb>cruption of Bubbles from the water, when <lb></lb>the airs preſſure was ſpeedily remov'd.<emph.end type="italics"></emph.end> 214 </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 29 <emph type="italics"></emph>Experiment, touching the cauſe <lb></lb>of the aſcent of Fumes and Vapors, wherein <lb></lb>'tis prov'd (from the ſeveral motions, which <lb></lb>the Fumes of a ſtrange ſmoaking Liquor, of <lb></lb>the Authors, were obſerv'd to have in the Re<lb></lb>ceiver, upon the exſuction of the Air) that <lb></lb>the reaſon of their aſcent proceeds from the <lb></lb>gravity of the ambient air, and not from any <lb></lb>poſitive levity of their own.<emph.end type="italics"></emph.end> 217 &c. </s></p><pb xlink:href="013/01/029.jpg"></pb><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 30 <emph type="italics"></emph>Experiment, concerning the na<lb></lb>ture of a fluid Body, illuſtrated by the exam<lb></lb>ple of ſmoak which in ſeveral circumſtances <lb></lb>ſeems very much to reſemble the property of a <lb></lb>fluid Body,<emph.end type="italics"></emph.end> 224 &c. <emph type="italics"></emph>A conjecture of the <lb></lb>cauſe of the Suns undulation.<emph.end type="italics"></emph.end> 228 </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 31 <emph type="italics"></emph>Experiment, concerning the<emph.end type="italics"></emph.end> Phæ<lb></lb>nomena <emph type="italics"></emph>of two flat Marbles exactly plain'd <lb></lb>and wrought together, and the true reaſon <lb></lb>thereof,<emph.end type="italics"></emph.end> 229. <emph type="italics"></emph>The Authors intention for the <lb></lb>further proſecution thereof, & what hindred <lb></lb>him; the reaſon why the under Marble did <lb></lb>not fal from the upper (being onely conjoynd <lb></lb>with Spirit of Wine) when the Receiver was <lb></lb>evacuated. </s> <s>And a notable relation concern<lb></lb>ing the coheſion of flat Bodies.<emph.end type="italics"></emph.end> 231 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 32 <emph type="italics"></emph>Experiment, touching the forcible <lb></lb>preſſure of the Air againſt the outward ſu<lb></lb>perficies of a Valve, faſten'd upon the ſtop<lb></lb>cock of the Receiver. </s> <s>The Diameter of it, <lb></lb>and the weight it ſuſtain'd.<emph.end type="italics"></emph.end> 233 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 33 <emph type="italics"></emph>experiment, touching the great preſ<lb></lb>ſure of the Air againſt the under ſuperficies <lb></lb>of the Sucker,<emph.end type="italics"></emph.end> 236 &c. <emph type="italics"></emph>what weight was re<lb></lb>quiſite to depreſs it, & what weight it would <lb></lb>lift and carry up with it,<emph.end type="italics"></emph.end> 239 &c. <emph type="italics"></emph>what im<lb></lb>provement & uſe there may be made of this <lb></lb>experiment,<emph.end type="italics"></emph.end> 242. <emph type="italics"></emph>A Diſcourſe touching the <lb></lb>nature of Suction, proving that<emph.end type="italics"></emph.end> fuga vacui <lb></lb><emph type="italics"></emph>is not the adequate cauſe thereof.<emph.end type="italics"></emph.end> 243 &c. </s></p><pb xlink:href="013/01/030.jpg"></pb><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 34<emph type="sup"></emph>th<emph.end type="sup"></emph.end> <emph type="italics"></emph>Experiment, containing ſeveral <lb></lb>attempts for the weighing of light Bodies in <lb></lb>the exhauſted Receiver.<emph.end type="italics"></emph.end> 258 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 35<emph type="sup"></emph>th<emph.end type="sup"></emph.end> <emph type="italics"></emph>Experiment, touching the cauſe <lb></lb>of Filtration, and the riſing of Water in<emph.end type="italics"></emph.end><lb></lb>Siphons, 262 &c. <emph type="italics"></emph>A relation of a new <lb></lb>kinde of<emph.end type="italics"></emph.end> Siphon, <emph type="italics"></emph>of the Authors, upon <lb></lb>the occaſion of trying the Experiment <lb></lb>lately obſerv'd by ſome French-men, and fur<lb></lb>ther improv'd by himſelf; and ſome conje<lb></lb>ctures touching the cauſe of the exhibited<emph.end type="italics"></emph.end><lb></lb>Phænomena. </s> <s>267 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 36<emph type="sup"></emph>th<emph.end type="sup"></emph.end> <emph type="italics"></emph>Experiment, touching the weigh<lb></lb>ing of a parcel of Air in the exhauſted Veſ<lb></lb>ſel; and ſome other Obſervations for the ex<lb></lb>plication thereof,<emph.end type="italics"></emph.end> 272 &c. <emph type="italics"></emph>An accidental <lb></lb>Experiment, tending to the further confir<lb></lb>mation of the Authors Reflections upon the <lb></lb>firſt Experiment; with a digreſsive Obſer<lb></lb>vation, noting the ſubtil penetrancy of ſome <lb></lb>Spirits, to exceed by far that of the Air,<emph.end type="italics"></emph.end> 275 <lb></lb>&c. <emph type="italics"></emph>And ſome other Experiments to ſhew the <lb></lb>difficulty of the ingreſs of the Air into the <lb></lb>pores or holes of ſome bodies into which Wa<lb></lb>ter will readily inſinuate it ſelf,<emph.end type="italics"></emph.end> 279 &c. <emph type="italics"></emph>with <lb></lb>a conjecture at the cauſe thereof,<emph.end type="italics"></emph.end> 282. <emph type="italics"></emph>The <lb></lb>Author returns to the proſecution if the in<lb></lb>quiry after the gravity of the Air: But firſt, <lb></lb>(upon the occaſion of the tenacity of a thin<emph.end type="italics"></emph.end><pb xlink:href="013/01/031.jpg"></pb><emph type="italics"></emph>Bubble of Glaſs) ſets down his thoughts con<lb></lb>cerning the ſtrange exuperancy of ſtrength <lb></lb>in Air, agitated by heat, above what the <lb></lb>ſame has unagitated,<emph.end type="italics"></emph.end> 283 &c. <emph type="italics"></emph>And then pro<lb></lb>ceeds to the examination of the weight of the <lb></lb>Air by an<emph.end type="italics"></emph.end> Æolipile, <emph type="italics"></emph>and compares the reſult <lb></lb>thereof, with that of<emph.end type="italics"></emph.end> Merſennus, 286. <emph type="italics"></emph>The <lb></lb>Opinions and Experiments of divers Au<lb></lb>thors, and ſome of his own, touching the <lb></lb>proportion of weight betwixt Water and Air, <lb></lb>are compar'd and examin'd by the Author,<emph.end type="italics"></emph.end><lb></lb>288. <emph type="italics"></emph>The reſult thereof,<emph.end type="italics"></emph.end> 290. Merſennus <lb></lb><emph type="italics"></emph>his obſervation reconcil'd, with that of the <lb></lb>Author; and the proportion between the gra<lb></lb>vity of Water and Air about<emph.end type="italics"></emph.end> London, 291 <lb></lb>&c. <emph type="italics"></emph>After the recital of the Opinions of ſe<lb></lb>veral Writers, touching the proportion of <lb></lb>gravity between Water and Quick-ſilver, <lb></lb>the Author ſets down his own tryals, made <lb></lb>ſeveral ways, together with his concluſion <lb></lb>therefrom,<emph.end type="italics"></emph.end> 293 &c. <emph type="italics"></emph>The uſe he makes of this <lb></lb>inquiry for the gheſsing at the height of the <lb></lb>Atmoſphere,<emph.end type="italics"></emph.end> 297. <emph type="italics"></emph>What other Experiments <lb></lb>are requiſite to the determination thereof.<emph.end type="italics"></emph.end><lb></lb>299 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 37<emph type="sup"></emph>th<emph.end type="sup"></emph.end> E<emph type="italics"></emph>xperiment, touching the ſtrange <lb></lb>and odde<emph.end type="italics"></emph.end> Phænomenon, <emph type="italics"></emph>of the ſudden flaſh<lb></lb>es of light in the cavity of the Receiver; the <lb></lb>ſeveral circumſtances and difficulties of it,<emph.end type="italics"></emph.end><pb xlink:href="013/01/032.jpg"></pb><emph type="italics"></emph>with ſome attempts towards the rendering at reaſon <lb></lb>thereof,<emph.end type="italics"></emph.end> 301, &c. <emph type="italics"></emph>The Difficulty of ſo doing fnr<lb></lb>ther ſhewn from the conſideration of the various <lb></lb>changes of Air which doe not immediatly fall un<lb></lb>der our ſenſes,<emph.end type="italics"></emph.end> 315. <emph type="italics"></emph>this laſt propoſition prou'd <lb></lb>by ſeverall obſervations.<emph.end type="italics"></emph.end> 316. </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 38. <emph type="italics"></emph>Experiment, touching the freezing of <lb></lb>water,<emph.end type="italics"></emph.end> 319. &c. <emph type="italics"></emph>Aproblem, (concerning the great <lb></lb>force wherewith a freezing Liquor extends its ſelfe,) <lb></lb>propoſ'd upon the Conſideration of divers admirable <lb></lb>effects wrought thereby.<emph.end type="italics"></emph.end> 320 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 39. <emph type="italics"></emph>Experiment, containing an inquiſition <lb></lb>after the temperature of the ſubſtance that remain'd <lb></lb>in the cavity of the Receiver, after the Air was well <lb></lb>exhauſted. </s> <s>The relation of a<emph.end type="italics"></emph.end> Phænomenon, <emph type="italics"></emph>ſeeming <lb></lb>to proceed from the ſwelling of the Glaſs. </s> <s>With an <lb></lb>advertiſement concerning the pliableneſs of Glaſs in <lb></lb>ſmall peices.<emph.end type="italics"></emph.end> 322. &c. </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 40. <emph type="italics"></emph>Experiment, touching the difficulty that <lb></lb>occur'd in making tryall whether rarified Air <lb></lb>were able to ſuſtaine flying inſects.<emph.end type="italics"></emph.end> 326. &c </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 41. <emph type="italics"></emph>Experiment, Exhibiting ſeverall try<lb></lb>alls touching the reſpiration of divers ſorts of ani<lb></lb>malls included in the Receiver,<emph.end type="italics"></emph.end> 328, &c. <emph type="italics"></emph>With a <lb></lb>digreſſion containing ſome doubts touching reſpira<lb></lb>tion wherein are delivered ſeverall Experiments re<lb></lb>lating thereunto.<emph.end type="italics"></emph.end> 335 &c. </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 42. <emph type="italics"></emph>Experiment, touching the differing o<lb></lb>peration of corroſive Liquors in the emptied Receiver <lb></lb>and in the open Air.<emph.end type="italics"></emph.end> 384 </s></p><p type="main"> <s><emph type="italics"></emph>The<emph.end type="italics"></emph.end> 43. <emph type="italics"></emph>Experiment, touching the ſpontaneous E<lb></lb>bullition of warm Liquors in the exhauſted Receiver.<emph.end type="italics"></emph.end> 388 </s></p><p type="main"> <s><emph type="italics"></emph>The Concluſion.<emph.end type="italics"></emph.end> 394 <pb xlink:href="013/01/033.jpg"></pb><pb xlink:href="013/01/034.jpg"></pb><figure id="id.013.01.034.1.jpg" xlink:href="013/01/034/1.jpg"></figure><pb xlink:href="013/01/035.jpg"></pb><figure id="id.013.01.035.1.jpg" xlink:href="013/01/035/1.jpg"></figure><pb xlink:href="013/01/036.jpg"></pb><figure id="id.013.01.036.1.jpg" xlink:href="013/01/036/1.jpg"></figure><pb xlink:href="013/01/037.jpg"></pb><figure id="id.013.01.037.1.jpg" xlink:href="013/01/037/1.jpg"></figure></s></p><pb xlink:href="013/01/038.jpg"></pb><pb xlink:href="013/01/039.jpg"></pb><pb xlink:href="013/01/040.jpg"></pb><pb xlink:href="013/01/041.jpg" pagenum="1"></pb><figure id="id.013.01.041.1.jpg" xlink:href="013/01/041/1.jpg"></figure><p type="main"> <s><emph type="center"></emph>TO THE <lb></lb>LORD <lb></lb>OF <lb></lb><emph type="italics"></emph>DUNGARVAN,<emph.end type="italics"></emph.end><lb></lb>My Honoured and Dear <lb></lb>NEPHEW.<emph.end type="center"></emph.end></s></p><p type="main"> <s><emph type="italics"></emph>My Dear Lord,<emph.end type="italics"></emph.end></s></p><p type="main"> <s>REceiving in your laſt from <lb></lb><emph type="italics"></emph>Paris,<emph.end type="italics"></emph.end> a deſire that I would <lb></lb>adde ſome more Experi<lb></lb>ments to thoſe I formerly <lb></lb>ſent You over: I could not <lb></lb>be ſo much your Servant as I am, without <lb></lb>looking upon that Deſire as a Com<lb></lb>mand; and conſequently, without think<lb></lb>ing my ſelf obliged to conſider by what <lb></lb>ſort of Experiments it might the moſt ac<lb></lb>ceptably be obey'd. </s> <s>And at the ſame <pb xlink:href="013/01/042.jpg" pagenum="2"></pb>time, perceiving by Letters from ſome <lb></lb>other Ingenious Perſons at <emph type="italics"></emph>Paris,<emph.end type="italics"></emph.end> that ſe<lb></lb>veral of the <emph type="italics"></emph>Virtuoſi<emph.end type="italics"></emph.end> there, were very <lb></lb>intent upon the examination of the Inte<lb></lb>reſt of the Ayr, in hindring the deſcent <lb></lb>of the Quick-ſilver, in the famous Expe<lb></lb>riment touching a <emph type="italics"></emph>Vacuum:<emph.end type="italics"></emph.end> I thought I <lb></lb>could not comply with your Deſires in a <lb></lb>more fit and ſeaſonable manner, then by <lb></lb>proſecuting and endeavoring to promote <lb></lb>that noble Experiment of <emph type="italics"></emph>Torricellius:<emph.end type="italics"></emph.end><lb></lb>and by preſenting your Lordſhip an ac<lb></lb>count of my attempts to illuſtrate a ſub<lb></lb>ject, about which, it's being ſo much diſ<lb></lb>courſ'd of where you are, together with <lb></lb>your inbred Curioſity, and love of Ex<lb></lb>perimental Learning, made me ſuppoſe <lb></lb>you ſufficiently inquiſitive. </s></p><p type="main"> <s>And though I pretend not to acquaint <lb></lb>you, on this occaſion, with any ſtore of <lb></lb>new Diſcoveries yet poſſibly I ſhall be ſo <lb></lb>happy, as to aſſiſt you to <emph type="italics"></emph>know<emph.end type="italics"></emph.end> ſomethings <lb></lb>which you did formerly but <emph type="italics"></emph>ſuppoſe;<emph.end type="italics"></emph.end> and <lb></lb>ſhall preſent you, if not with new Theo<lb></lb>ries, at leaſt with new <emph type="italics"></emph>Proofs<emph.end type="italics"></emph.end> of ſuch as <lb></lb>are not yet become unqueſtionable. </s> <s>And <lb></lb>if what I ſhall deliver, have the good for<lb></lb>tune to encourage and aſſiſt you to proſe<lb></lb>cute the Hints it will afford, I ſhall ac-<pb xlink:href="013/01/043.jpg" pagenum="3"></pb>count my ſelf, in paying of a duty to <lb></lb>you, to have done a piece of Service to <lb></lb>the Commonwealth of Learning. </s> <s>Since <lb></lb>it may highly conduce to the advance<lb></lb>ment of that Experimental Philoſophy, <lb></lb>the effectual purſuit of which, requires <lb></lb>as well a Purſe as a Brain, to endeere it <lb></lb>to <emph type="italics"></emph>hopeful<emph.end type="italics"></emph.end> Perſons of your Quality: who <lb></lb>may accompliſh many things which o<lb></lb>thers can but <emph type="italics"></emph>wiſh<emph.end type="italics"></emph.end> or, at moſt, but <emph type="italics"></emph>deſign,<emph.end type="italics"></emph.end><lb></lb>by being able to imploy the Preſents of <lb></lb>Fortune in the ſearch of the Myſteries of <lb></lb>Nature. </s></p><p type="main"> <s>And I am not faintly induc'd to make <lb></lb>choice of this Subject, rather then any <lb></lb>of the expected Chymical ones, to enter<lb></lb>tain your Lordſhip upon, by theſe two <lb></lb>Conſiderations: The one, That the Ayr <lb></lb>being ſo neceſſary to humane Life, that <lb></lb>not onely the generality of Men, but <lb></lb>moſt other Creatures that breath, can<lb></lb>not live many <emph type="italics"></emph>minutes<emph.end type="italics"></emph.end> without it; any <lb></lb>conſiderable diſcovery of its Nature, <lb></lb>ſeems likely to prove of moment to <lb></lb>Man-kinde. </s> <s>And the other is, That the <lb></lb>Ambient Ayr, being that whereto both <lb></lb>our own Bodies, and moſt of the others <lb></lb>we deal with here below, are almoſt per<lb></lb>petually contiguous; not onely its alte-<pb xlink:href="013/01/044.jpg" pagenum="4"></pb>rations have a notable and manifeſt ſhare <lb></lb>in thoſe obvious effects, that men have <lb></lb>already been invited to aſcribe thereunto <lb></lb>ſuch as are the various diſtempers inci<lb></lb>dent to humane Bodies, eſpecially if cra<lb></lb>zy, in the Spring, the Autumn, and alſo <lb></lb>on moſt of the great and ſudden changes <lb></lb>of Weather) but likewiſe, that the fur<lb></lb>ther diſcovery of the nature of the Ayr, <lb></lb>will probably diſcover to us, that it con<lb></lb>curs more or leſs to the exhibiting of ma<lb></lb>ny <emph type="italics"></emph>Phænomena,<emph.end type="italics"></emph.end> in which it hath hither<lb></lb>to ſcarce been ſuſpected to have any inte<lb></lb>reſt. </s> <s>So that a True Account of any <lb></lb>Experiment that is New concerning a <lb></lb>thing, wherewith we have ſuch conſtant <lb></lb>and neceſſary intercourſe, may not one<lb></lb>ly prove of ſome advantage to humane <lb></lb>Life, but gratifie Philoſophers, by pro<lb></lb>moting their Speculations on a Subject <lb></lb>which hath ſo much opportunity to ſolli<lb></lb>cite their Curioſity. </s></p><p type="main"> <s>And I ſhould immediately proceed to <lb></lb>the mention of my Experiments, but that <lb></lb>I like too well that worthy ſaying of the <lb></lb>Naturaliſt <emph type="italics"></emph>Pliny, Benignum eſt<emph.end type="italics"></emph.end></s></p><p type="main"> <s><arrow.to.target n="marg1"></arrow.to.target><lb></lb><emph type="italics"></emph>& plenum ingenui pudor is, fateri <lb></lb>per quos profeceris,<emph.end type="italics"></emph.end> not to con<lb></lb>form to it, by acquainting your Lord-<pb xlink:href="013/01/045.jpg" pagenum="5"></pb>ſhip, in the firſt place, with the Hint I <lb></lb>had of the Engine I am to entertain you <lb></lb>of. </s> <s>You may be pleaſ'd to remember, <lb></lb>that a while before our ſeparation in <emph type="italics"></emph>Eng<lb></lb>land,<emph.end type="italics"></emph.end> I told you of a Book that I had <lb></lb>heard of, but not peruſ'd, publiſh'd by <lb></lb>the induſtrious Jeſuit <emph type="italics"></emph>Schottus,<emph.end type="italics"></emph.end> wherein <lb></lb>'twas ſaid, He related how that ingenious <lb></lb>Gentleman <emph type="italics"></emph>Otto Gericke,<emph.end type="italics"></emph.end> Conſul of <emph type="italics"></emph>Mag<lb></lb>deburg,<emph.end type="italics"></emph.end> had lately practiced in <emph type="italics"></emph>Germany<emph.end type="italics"></emph.end> a <lb></lb>way of emptying Glaſs Veſſels, by ſuck<lb></lb>ing out the Ayr at the mouth of the Veſ<lb></lb>ſel, plung'd under water: And you may <lb></lb>alſo perhaps remember, that I expreſſ'd <lb></lb>my ſelf much delighted with this Expe<lb></lb>riment, ſince thereby the great force of <lb></lb>the external Air (either ruſhing in at the <lb></lb>open'd Orifice of the empty'd Veſſel, or <lb></lb>violently forcing up the Water into it) <lb></lb>was rendred more obvious and conſpicu<lb></lb>ous, than in any Experiment that I had <lb></lb>formerly ſeen. </s> <s>And though it may appear <lb></lb>by ſome of thoſe Writings I ſometimes <lb></lb>fhew'd your Lordſhip, that I had been ſol<lb></lb>licitous to try things upon the ſame <lb></lb>ground; yet in regard this Gentleman <lb></lb>was before-hand with me in producing <lb></lb>ſuch conſiderable effects, by means of the <lb></lb>exſuction of Air, I think my ſelf oblig'd <pb xlink:href="013/01/046.jpg" pagenum="6"></pb>to acknowledge the Aſſiſtance, and En<lb></lb>couragement the Report of his perfor<lb></lb>mances hath afforded me. </s></p><p type="margin"> <s><margin.target id="marg1"></margin.target><emph type="italics"></emph>In <gap></gap>. <lb></lb></s> <s>lib.<emph.end type="italics"></emph.end> 1.</s></p><p type="main"> <s>But as few inventions happen to be at <lb></lb>firſt ſo compleat, as not to be either ble<lb></lb>miſhd with ſome deficiencies needful to be <lb></lb>remedy'd, or otherwiſe capable of im<lb></lb>provement: ſo when the Engine we <lb></lb>have been ſpeaking of, comes to be more <lb></lb>attentively conſider'd, there will appear <lb></lb>two very conſiderable things to be de<lb></lb>ſir'd in it. </s> <s>For firſt, the <emph type="italics"></emph>Wind-Pump<emph.end type="italics"></emph.end> (as <lb></lb>ſome body not improperly calls it) is ſo <lb></lb>contriv'd, that to evacuate the Veſſel <lb></lb>there is requir'd the continual labor of <lb></lb>two ſtrong men for divers hours. </s> <s>And <lb></lb>next (which is an imperfection of much <lb></lb>greater moment) the Receiver, or Glaſs <lb></lb>to be empty'd, conſiſting of one entire <lb></lb>and uninterrupted Globe and Neck of <lb></lb>Glaſs; the whole Engine is ſo made, that <lb></lb>things cannot be convey'd into it, where<lb></lb>on to try Experiments: So that there <lb></lb>ſeems but little (if any thing) more to be <lb></lb>expected from it, then thoſe very few <lb></lb><emph type="italics"></emph>Phænomena<emph.end type="italics"></emph.end> that have been already ob<lb></lb>ſerv'd by the Author, and Recorded by <lb></lb><emph type="italics"></emph>Schottus.<emph.end type="italics"></emph.end></s><s> Wherefore to remedy theſe <lb></lb>Inconveniences, I put both Mr. <emph type="italics"></emph>G.<emph.end type="italics"></emph.end><pb xlink:href="013/01/047.jpg" pagenum="7"></pb>and <emph type="italics"></emph>R. Hook<emph.end type="italics"></emph.end> (who hath alſo the Honor to <lb></lb>be known to your Lordſhip, and was with <lb></lb>me when I had theſe things under conſi<lb></lb>deration) to contrive ſome Air Pump, <lb></lb>that might not, like the other, need to <lb></lb>be kept under water (which on divers oc<lb></lb>caſions is inconvenient) & might be more <lb></lb>eaſily manag'd: And after an unſucceſsful <lb></lb>try all or two of ways propoſ'd by o<lb></lb>thers, the laſt nam'd Perſon fitted me <lb></lb>with a Pump, anon to be deſcrib'd. </s> <s>And <lb></lb>thus the firſt Imperfection of the <emph type="italics"></emph>German<emph.end type="italics"></emph.end><lb></lb>Engine, was in good meaſure, though <lb></lb>not perfectly, remedy'd: And to ſupply <lb></lb>the ſecond deſect, it was conſidered that <lb></lb>it would not perhaps prove impoſſible to <lb></lb>leave in the Glaſs to be empty'd, a hole <lb></lb>large enough to put in a Mans Arm <lb></lb>cloath'd; and conſequently other Bodies, <lb></lb>not bigger then it, or longer then the in<lb></lb>ſide of the Veſſel. </s> <s>And this Deſign <lb></lb>ſeem'd the more hopefull, becauſe I re<lb></lb>membred, that having ſeveral years be<lb></lb>fore often made the Experiment <emph type="italics"></emph>De Va<lb></lb>cuo<emph.end type="italics"></emph.end> with my own hands; I had, to exa<lb></lb>mine ſome conjectures that occurr'd to <lb></lb>me about it, cauſed Glaſſes to be made <lb></lb>with a hole at that end, which uſes to be <lb></lb>ſeal'd up, and had nevertheleſs been able <pb xlink:href="013/01/048.jpg" pagenum="8"></pb>as occaſion requir'd, to make uſe of ſuch <lb></lb>Tubes, as if no ſuch holes had been left <lb></lb>in them; by deviſing ſtopples for them, <lb></lb>made of the common Plaiſter call'd <emph type="italics"></emph>Dia<lb></lb>chylon:<emph.end type="italics"></emph.end> which I rightly enough gheſſ'd, <lb></lb>would, by reaſon of the exquiſite com<lb></lb>mixtion of its ſmall parts, and cloſeneſs <lb></lb>of its texture, deny all acceſs to the ex<lb></lb>ternal Air. </s> <s>Wherefore, ſuppoſing that <lb></lb>by the help of ſuch Plaiſters, carefully <lb></lb>laid upon the commiſſures of the ſtopple <lb></lb>and hole to be made in the Receiver, the <lb></lb>external Air might be hindred from inſi<lb></lb>nuating it ſelf between them into the Veſ<lb></lb>ſel, we cauſ'd ſeveral ſuch Glaſſes, as <lb></lb>you will finde deſcrib'd a little lower, to <lb></lb>be blown at the Glaſs-houſe; and though <lb></lb>we could not get the Work-men to blow <lb></lb>any of them ſo large, or of ſo conveni<lb></lb>ent a ſhape as we would fain have had; yet <lb></lb>finding one to be tolerably fit, and leſs <lb></lb>unfit then any of the reſt, we were con<lb></lb>tent to make uſe of it in that En<lb></lb>gine: Of which, I ſuppoſe, you by this <lb></lb>time expect the Deſcription, in order to <lb></lb>the Recital of the <emph type="italics"></emph>Phænomena<emph.end type="italics"></emph.end> exhibited <lb></lb>by it. </s></p><p type="main"> <s>To give your Lordſhip then, in the <lb></lb>firſt place, ſome account of the Engine it <pb xlink:href="013/01/049.jpg" pagenum="9"></pb>ſelf: It conſiſts of two principal parts; a <lb></lb>glaſs Veſſel, and a Pump to draw the Air <lb></lb>out of it. </s></p><p type="main"> <s>The former of theſe (which we, with <lb></lb>the Glaſs men, ſhall often call a Receiver, <lb></lb>for its affinity to the large Veſſels of that <lb></lb>name, uſed by Chymiſts) conſiſts of a <lb></lb>Glaſs with a wide hole at the top, of a <lb></lb>cover to that hole, and of a ſtop-cock <lb></lb>faſtned to the end of the neck, at the <lb></lb>bottom. </s></p><p type="main"> <s>The ſhape of the Glaſs, you will find <lb></lb>expreſſ'd in the firſt Figure of the annex<lb></lb>ed Scheme. </s> <s>And for the ſize of it, it <lb></lb>contain'd about 30 Wine Quarts, each of <lb></lb>them containing near two pound (of 16 <lb></lb>Ounces to the pound) of water: We <lb></lb>ſhould have been better pleaſ'd with a <lb></lb>more capacious Veſſel, but the Glaſs-men <lb></lb>profeſſed themſelves unable to blow a <lb></lb>larger, of ſuch a thickneſs and ſhape as <lb></lb>was requiſite to our purpoſe. </s></p><p type="main"> <s>At the very top of the Veſſel, (A) you <lb></lb>may obſerve a round hole, whoſe Dia<lb></lb>meter (B C) is of about four inches; and <lb></lb>whereof, the Orifice is incircled with a <lb></lb>lip of Glaſs, almoſt an inch high: For <lb></lb>the making of which lip, it was requiſite <lb></lb>(to mention that upon the by, in caſe <pb xlink:href="013/01/050.jpg" pagenum="10"></pb>your Lordſhip ſhould have ſuch another <lb></lb>Engine made for you) to have a hollow <lb></lb>and tapering Pipe of Glaſs drawn out, <lb></lb>whereof the Orifice above mentioned <lb></lb>was the Baſis, and then to have the cone <lb></lb>cut off with a hot Iron, within about an <lb></lb>Inch of the Points (B C.) </s></p><p type="main"> <s>The uſe of the lip, is to ſuſtain the <lb></lb>cover delineated in the ſecond Figure; <lb></lb>where (D E) points out a braſs Ring, ſo <lb></lb>caſt, as that it doth within and without <lb></lb>cover the lip (B C) of the firſt Figure, <lb></lb>and is cemented on upon it with a ſtrong <lb></lb>and cloſe Cement. </s> <s>To the inward taper<lb></lb>ing Orifice of this Ring (which is about <lb></lb>three Inches over) are exquiſitely ground <lb></lb>the ſides of the Braſs ſtopple (F G;) ſo <lb></lb>that the concave ſuperficies of the one, <lb></lb>and the convex of the other, may touch <lb></lb>one another in ſo many places, as may <lb></lb>leave as little acceſs, as poſſible, to the ex<lb></lb>ternal Air: And in the midſt of this cover <lb></lb>is left a hole (H I) of about half an inch <lb></lb>over, invironed alſo with a ring or ſocket <lb></lb>of the ſame mettal, and fitted likewiſe <lb></lb>with a braſs ſtopple (K) made in the form <lb></lb>of the Key of a ſtop-cock, and exactly <lb></lb>ground into the hole (H I) it is to fill; ſo <lb></lb>as that though it be turn'd round in the <pb xlink:href="013/01/051.jpg" pagenum="11"></pb>cavity it poſſeſſes, it will not let in the <lb></lb>Air, and yet may be put in or taken out <lb></lb>at pleaſure, for uſes to be hereafter men<lb></lb>tioned. </s> <s>In order to ſome of which, it is <lb></lb>perforated with a little hole, (8) traverſing <lb></lb>the whole thickneſs of it at the lower <lb></lb>end; through which, and a little braſs <lb></lb>Ring (L) faſtned to one ſide, (no matter <lb></lb>which) of the bottom of the ſtopple <lb></lb>(FG) a ſtring (8, 9, 10) might paſs, to <lb></lb>be imploy'd to move ſome things in the <lb></lb>capacity of the empty'd Veſſel; without <lb></lb>any where unſtopping it. </s></p><p type="main"> <s>The laſt thing belonging to our Recei<lb></lb>ver, is the ſtop-cock deſigned in the firſt <lb></lb>Figure by (N.) for the better faſtening <lb></lb>of which to the neck, and exacter excluſi<lb></lb>on of the Air, there was ſoder'd on to <lb></lb>the ſhank of the Cock (X) a Plate of <lb></lb>Tin, (MTUW) long enough to cover <lb></lb>the neck of the Receiver. </s> <s>But becauſe <lb></lb>the cementing of this was a matter of <lb></lb>ſome difficulty, it will not be amiſs to <lb></lb>mention here the manner of it, which <lb></lb>was, That the cavity of the tin Plate was <lb></lb>fill'd with a melted Cement, made of <lb></lb>Pitch, Roſin, and Wood-aſhes, well in<lb></lb>corporated; and to hinder this liquid <lb></lb>Mixture from getting into the Orifice (Z) <pb xlink:href="013/01/052.jpg" pagenum="12"></pb>of the ſhank, (X) that hole was ſtopt <lb></lb>with a Cork, to which was faſtned a ſtring, <lb></lb>whereby it might be pull'd out of the up<lb></lb>per Orifice of the Receiver; and then, <lb></lb>the glaſs neck of the Receiver being well <lb></lb>warm'd, was thruſt into this Cement, and <lb></lb>over the ſhank whereby it was effected, <lb></lb>that all the ſpace betwixt the tin Plate and <lb></lb>the Receiver, and betwixt the internal <lb></lb>ſuperficies of the Receiver, and the <lb></lb>ſhanck of the Cock, was filld with the <lb></lb>Cement; and ſo we have diſpach'd the <lb></lb>firſt and upper part of the Engine. </s></p><p type="main"> <s>The undermoſt remaining part conſiſts <lb></lb>of a Frame, and of a ſucking Pump, or <lb></lb>as we formerly call'd it, an Air Pump, ſup<lb></lb>ported by it: The Frame is of Wood, <lb></lb>ſmall, but very ſtrong, conſiſting of three <lb></lb>legs, (111) ſo plac'd, that one ſide of <lb></lb>it may ſtand perpendicular, that the free <lb></lb>motion of the hand may not be hindered. <lb></lb></s> <s>In the midſt of which frame, is tranſverſly <lb></lb>nail'd a board, (222) which may not im<lb></lb>properly be call'd a Midriff, upon which <lb></lb>reſts, and to which is ſtrongly faſtned, the <lb></lb>main part of the Pump it ſelf, which is <lb></lb>the onely thing remaining to be deſcri<lb></lb>bed. </s></p><p type="main"> <s>The Pump conſiſts of four parts, a <pb xlink:href="013/01/053.jpg" pagenum="13"></pb>hollow Cylindre, a Sucker, a handle to <lb></lb>move that Sucker, and a Valve. </s></p><p type="main"> <s>The Cylindre was (by a pattern) caſt <lb></lb>of braſs; it is in length about 14 inches, <lb></lb>thick enough to be very ſtrong, notwith<lb></lb>ſtanding the Cylindrical cavity left with<lb></lb>in it; this cavity is about three inches <lb></lb>Diameter, and makes as exact a Cylin<lb></lb>dre as the Artificer was able to bore. <lb></lb></s> <s>This hollow Cylindre is fitted with a ſuck<lb></lb>er, (4455) conſiſting of two parts, the <lb></lb>one (44) ſomewhat leſs in Diameter then <lb></lb>the cavity of the Cylindre, upon which <lb></lb>is nail'd a good thick piece of tan'd ſhoe <lb></lb>Leather, which will go ſo cloſe to the <lb></lb>Cylindre, that it will need to be very <lb></lb>forcibly knock'd and ram'd in, if at any <lb></lb>time it be taken out, which is therefore <lb></lb>done, that it may the more exactly hin<lb></lb>der the Air from inſinuating it ſelf be<lb></lb>twixt it and the ſides of the Cylindre <lb></lb>whereon it is to move. </s></p><p type="main"> <s>To the midſt of this former part of the <lb></lb>Sucker is ſtrongly faſtned the other, <lb></lb>namely a thick and narrow plate of Iron, <lb></lb>(55) ſomewhat longer then the Cylindre, <lb></lb>one of whoſe edges is ſmooth, but at the <lb></lb>other edge it is indented (as I may ſo <lb></lb>ſpeak) with a row of teeth delineated in <pb xlink:href="013/01/054.jpg" pagenum="14"></pb>the Scheme, into whoſe intervals are to <lb></lb>be fitted, the teeth of a ſmall Iron nut; <lb></lb>(<gap></gap>) (as Tradeſ-men call it) which is faſt<lb></lb>ned by two ſtaples (22) to the under ſide <lb></lb>of the formerly mention'd tranſverſe <lb></lb>board (222) on which the Cylindre reſts, <lb></lb>and is turn'd to and fro by the third piece <lb></lb>of this Pump, namely, the handle or <lb></lb><emph type="italics"></emph>manubrium,<emph.end type="italics"></emph.end> (7) of which the Figure gives <lb></lb>a ſufficient deſcription. </s></p><p type="main"> <s>The fourth and laſt part of this Cylin<lb></lb>dre, is the Valve, (R) conſiſting of a <lb></lb>hole bored through at the top of the Cy<lb></lb>lindre, a little tapering towards the cavi<lb></lb>ty; into which hole is ground a tapering <lb></lb>Peg of braſs, to be thruſt in, and taken <lb></lb>out at pleaſure. </s></p><p type="main"> <s>The Engine being thus deſcrib'd, it <lb></lb>will be requiſite to adde, that ſomething <lb></lb>is wont to be done before it be ſet on <lb></lb>work, for the more eaſie moving of the <lb></lb>Sucker, and for the better excluſion of <lb></lb>the outward Air: which when the Veſſel <lb></lb>begins to be exhauſted, is much more dif<lb></lb>ficult to be kept out then one would eaſi<lb></lb>ly imagine. </s></p><p type="main"> <s>There muſt then be firſt powr'd in at <lb></lb>the top of the Receiver a little ſallad oyl, <lb></lb>partly to fill up any ſmall intervalls that <pb xlink:href="013/01/055.jpg" pagenum="15"></pb>may happen to be betwixt the contigu<lb></lb>ous ſurfaces of the internal parts of the <lb></lb>Stop-cock: And partly that it may be <lb></lb>the more eaſie to turn the Key (S) back<lb></lb>wards and forwards. </s> <s>Pretty ſtore of oyl <lb></lb>muſt alſo be pour'd into the Cylindre, <lb></lb>both that the Sucker may ſlip up and <lb></lb>down in it the more ſmoothly and freely, <lb></lb>and that the Air might be the better <lb></lb>hindred from getting in between them: <lb></lb>And for the like reaſons, a little oyl is to <lb></lb>be uſed alſo about the Valve. </s> <s>Upon <lb></lb>which occaſion, it would not be omitted <lb></lb>(for it is ſtrange) that oftentimes, when <lb></lb>neither the pouring in of water, nor even <lb></lb>of oyl alone, prov'd capable to make the <lb></lb>Sucker move eaſily enough in the Cylin<lb></lb>der; a mixture of both thoſe Liquors <lb></lb>would readily (ſometimes even to admi<lb></lb>ration) perform the deſired effect. </s> <s>And <lb></lb>laſtly, the braſs cover of the Receiver, <lb></lb>being put into the braſs ring formerly de<lb></lb>ſcrib'd, that no Air may get between <lb></lb>them, it will be very requiſite to plaiſter <lb></lb>over very carefully the upper edges of <lb></lb>both, with the plaiſter formerly mention<lb></lb>ed, or ſome other as cloſe, which is to be <lb></lb>ſpread upon the edges with a hot Iron; <lb></lb>that being melted, it may run into and <pb xlink:href="013/01/056.jpg" pagenum="16"></pb>fill up all the crannies, or other little ca<lb></lb>vities, at which the Air might otherwiſe <lb></lb>get entrance. </s></p><p type="main"> <s>All things being thus fitted, and the <lb></lb>lower ſhank (O) of the ſtop-cock being <lb></lb>put into the upper Orifice of the Cylin<lb></lb>der (&), into which it was exactly ground; <lb></lb>the Experimenter is firſt, by turning the <lb></lb>handle, to force the Sucker to the top of <lb></lb>the Cylinder, that there may be no Air <lb></lb>left in the upper part of it: Then ſhut<lb></lb>ting the Valve with the Plug, and turning <lb></lb>the other way, he is to draw down the <lb></lb>Sucker to the bottom of the Cylinder; <lb></lb>by which motion of the Sucker, the Air <lb></lb>that was formerly in the Cylinder being <lb></lb>thruſt out, and none being permitted to <lb></lb>ſucceed in its room, 'tis manifeſt that the <lb></lb>cavity of the Cylinder muſt be empty, <lb></lb>in reference to the Air: So that if there<lb></lb>upon the Key of the Stop-cock be ſo <lb></lb>turn'd, as that through the perforation of <lb></lb>it, a free paſſage be opened betwixt the <lb></lb>Cylinder and the Receiver, part of the <lb></lb>Air formerly contain'd in the Receiver, <lb></lb>will nimbly deſcend into the Cylinder. <lb></lb></s> <s>And this Air, being by the turning back <lb></lb>of the Key hinder'd from the returning <lb></lb>into the Receiver, may, by the opening <pb xlink:href="013/01/057.jpg" pagenum="17"></pb>of the Valve, and forcing up of the Suck<lb></lb>er to the top of the Cylinder again, be <lb></lb>driven out into the open Air. </s> <s>And thus <lb></lb>by the repetition of the motion of the <lb></lb>Sucker upward and downward, and by op<lb></lb>portunely turning the Key, and ſtopping <lb></lb>the Valve, as occaſion requires, more or <lb></lb>leſs Air may be ſuck'd out of the Recei<lb></lb>ver, according to the exigency of the Ex<lb></lb>periment, and the intention of him that <lb></lb>makes it. </s></p><p type="main"> <s>Your Lordſhip will, perhaps, think that <lb></lb>I have been unneceſſarily prolix in this <lb></lb>firſt part of my Diſcourſe: But if you <lb></lb>had ſeen how many unexpected difficul<lb></lb>ties we found to keep out the externall <lb></lb>Air, even for a little while, when ſome <lb></lb>conſiderable part of the internal had been <lb></lb>ſuckt out; You would peradventure al<lb></lb>low, that I might have ſet down more <lb></lb>circumſtances then I have, without ſet<lb></lb>ting down any, whoſe knowledge, he that <lb></lb>ſhall try the Experiment may not have <lb></lb>need of. </s> <s>Which is ſo true, that, before we <lb></lb>proceed any further, I cannot think it un<lb></lb>ſeaſonable to advertiſe Your Lordſhip, <lb></lb>that there are two chief ſorts of Experi<lb></lb>ments, which we deſign'd in our Engine <lb></lb>to make tryal of: The one, ſuch as may <pb xlink:href="013/01/058.jpg" pagenum="18"></pb>be quickly diſpatcht, and therefore may <lb></lb>be try'd in our Engine, though it leak a <lb></lb>little; becauſe the Air may be faſter drawn <lb></lb>out, by nimbly plying the Pump, then <lb></lb>it can get in at undiſcern'd leaks; I ſay at <lb></lb>undiſcern'd leaks, becauſe ſuch as are big <lb></lb>enough to be diſcover'd can ſcarce be un<lb></lb>eaſie to be ſtopt. </s> <s>The other ſort of Ex<lb></lb>periments conſiſts of thoſe that require <lb></lb>not onely that the internal Air be drawn <lb></lb>out of the Receiver, but that it be like<lb></lb>wiſe for a long time kept out of it. </s> <s>Such <lb></lb>are the preſervation of Animal and o<lb></lb>ther Bodies therein, the germination and <lb></lb>growth of Vegetables, and other tryals <lb></lb>of ſeveral ſorts, which it is apparent can<lb></lb>not be well made unleſs the external Air <lb></lb>can, for a competent while, be excluded: <lb></lb>Since even at a very ſmall leak there may <lb></lb>enough get in, to make the <emph type="italics"></emph>Vacuum<emph.end type="italics"></emph.end> ſoon <lb></lb>looſe that name; by which I here declare <lb></lb>once for all, that I underſtand not a ſpace <lb></lb>wherein there is no body at all, but ſuch <lb></lb>as is either altogether, or almoſt totally <lb></lb>void of Air. </s></p><p type="main"> <s>Now this diſtinction of Experiments <lb></lb>I thought fit to premiſe to the enſuing <lb></lb>Narratives, becauſe upon tryal, we found <lb></lb>it ſo exceeding (and ſcarce imaginable) dif-<pb xlink:href="013/01/059.jpg" pagenum="19"></pb>ficult a matter, to keep out the Air from <lb></lb>getting at all in at any imperceptible hole <lb></lb>or flaw whatſoever, in a Veſſel immedi<lb></lb>ately ſurrounded with the compreſſed At<lb></lb>moſphere, that in ſpight of all our care <lb></lb>and diligence, we never were able totally <lb></lb>to exhauſt the Receiver, or keep it when <lb></lb>it was almoſt empty, any conſiderable <lb></lb>time, from leaking more or leſs: although <lb></lb>(as we have lately intimated) by unwearyed <lb></lb>quickneſs in plying the Pump, the inter<lb></lb>nall Air can be much faſter drawn out <lb></lb>then the external can get in, till the Re<lb></lb>ceiver come to be almoſt quite empty. <lb></lb></s> <s>And that's enough to enable men to diſ<lb></lb>cover hitherto unobſerved <emph type="italics"></emph>Phænomena<emph.end type="italics"></emph.end> of <lb></lb>Nature. </s></p><p type="main"> <s>The Experiments therefore of the firſt <lb></lb>ſort, will, I fear, prove the onely ones <lb></lb>wherewith my Avocations will allow me <lb></lb>to entertain Your Lordſhip in this Letter. <lb></lb></s> <s>For till your further Commands ſhall en<lb></lb>gage me to undertake, by Gods permiſ<lb></lb>ſion, ſuch an Employment, and more lea<lb></lb>ſure ſhall better fit me for it, I know not <lb></lb>whether I ſhall be in a condition to try <lb></lb>what may be done, to enable me to give <lb></lb>you ſome account of the other ſort of <lb></lb>Experiments alſo. </s></p><pb xlink:href="013/01/060.jpg" pagenum="20"></pb><p type="main"> <s>TO proceed now to the <emph type="italics"></emph>Phænomena,<emph.end type="italics"></emph.end><lb></lb><arrow.to.target n="marg2"></arrow.to.target><lb></lb>exhibited to us by the Engine above <lb></lb>deſcribed; I hold it not unfit to begin <lb></lb>with what does conſtantly and regularly <lb></lb>offer it ſelf to our obſervation, as depend<lb></lb>ing upon the Fabrick of the Engine it ſelf, <lb></lb>and not upon the nature of this or that <lb></lb>particular Experiment which 'tis employ<lb></lb>ed to try. </s></p><p type="margin"> <s><margin.target id="marg2"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 1.</s></p><p type="main"> <s>Firſt, Then upon the drawing down <lb></lb>of the Sucker, (the Valve being ſhut) the <lb></lb>Cylindrical ſpace, deſerted by the Sucker, <lb></lb>is left de void of Air; and therefore, up<lb></lb>on the turning of the Key, the Air con<lb></lb>tained in the Receiver ruſhes into the em<lb></lb>ptyed Cylinder, till the Air in both thoſe <lb></lb>Veſſels be brought to about an equal <lb></lb>meaſure of dilatation. </s> <s>And therefore, <lb></lb>upon ſhutting the Receiver by returning <lb></lb>the Key, if you open the Valve, and force <lb></lb>up the Sucker again, you will finde, that <lb></lb>after this firſt exſuction you will drive <lb></lb>out almoſt a whole Cylinder full of Air: <lb></lb>But at the following exſuctions, you will <lb></lb>draw leſs and leſs of Air out of the Recei<lb></lb>ver into the Cylinder, becauſe that there <lb></lb>will ſtill remain leſs and leſs Air in the <pb xlink:href="013/01/061.jpg" pagenum="21"></pb>Receiver it ſelf; and conſequently, the <lb></lb>Particles of the remaining Air, having <lb></lb>more room to extend themſelves in, will <lb></lb>leſs preſs out one another. </s> <s>This you will <lb></lb>eaſily perceive, by finding, that you ſtill <lb></lb>force leſs and leſs Air out of the Cylin<lb></lb>der; ſo that when the Receiver is almoſt <lb></lb>exhauſted, you may force up the Sucker <lb></lb>almoſt to the top of the Cylinder, be<lb></lb>fore you will need to unſtop the Valve to <lb></lb>let out any Air: And if at ſuch time, the <lb></lb>Valve being ſhut, you let go the handle of <lb></lb>the Pump, you will finde the Sucker for<lb></lb>cibly carryed up to the top of the Cylin<lb></lb>der, by the protruſion of the external Air; <lb></lb>which, being much leſs rarified then that <lb></lb>within the Cylinder, muſt have a more <lb></lb>forcible preſſure upon the Sucker, then <lb></lb>the internal is able to reſiſt: And by this <lb></lb>means you may know how far you have <lb></lb>emptyed the Receiver. </s> <s>And to this we <lb></lb>may adde, on this occaſion, that conſtant<lb></lb>ly upon the turning of the Key to let out <lb></lb>the Air from the Receiver, into the em<lb></lb>ptied Cylinder, there is immediately pro<lb></lb>duced a conſiderably brisk noiſe, eſpeci<lb></lb>ally whil'ſt there is any plenty of Air in <lb></lb>the Receiver. </s></p><pb xlink:href="013/01/062.jpg" pagenum="22"></pb><p type="main"> <s>For the more eaſie underſtanding of the <lb></lb>Experiments tryable by our Engine, I <lb></lb>thought it not ſuperfluous, nor unſeaſon<lb></lb>able in the recital of this firſt of them, to <lb></lb>inſinuate that notion by which it ſeems <lb></lb>likely that moſt, if not all, of them will <lb></lb>prove explicable. </s> <s>Your Lordſhip will <lb></lb>eaſily ſuppoſe, that the Notion I ſpeak <lb></lb>of is, That there is a Spring, or Elaſti<lb></lb>cal power in the Air we live in. </s> <s>By which <lb></lb><foreign lang="grc">ἐλατγ̀ρ</foreign> or Spring of the Air, that which <lb></lb>I mean is this: That our Air either con<lb></lb>ſiſts of, or at leaſt abounds with, parts of <lb></lb>ſuch a nature, that in caſe they be bent or <lb></lb>compreſſ'd by the weight of the incum<lb></lb>bent part of the Atmoſphere, or by any o<lb></lb>ther Body, they do endeavor, as much as <lb></lb>in them lies, to free themſelves from that <lb></lb>preſſure, by bearing againſt the contigu<lb></lb>ous Bodies that keep them bent; and, <lb></lb>aſſoon as thoſe Bodies are remov'd or <lb></lb>reduced to give them way, by preſently <lb></lb>unbending and ſtretching out themſelves, <lb></lb>either quite, or ſo far forth as the con<lb></lb>tiguous Bodies that reſiſt them will per<lb></lb>mit, and thereby expanding the whole <lb></lb>parcel of Air, theſe elaſtical Bodies com<lb></lb>poſe. </s></p><pb xlink:href="013/01/063.jpg" pagenum="23"></pb><p type="main"> <s>This Notion may perhaps be ſome<lb></lb>what further explain'd, by conceiving the <lb></lb>Air near the Earth to be ſuch a heap of <lb></lb>little Bodies, lying one upon another, as <lb></lb>may be reſembled to a Fleece of Wooll. <lb></lb></s> <s>For this (to omit other likeneſſes betwixt <lb></lb>them) conſiſts of many ſlender and flexi<lb></lb>ble Hairs; each of which, may indeed, <lb></lb>like a little Spring, be eaſily bent or roul<lb></lb>ed up; but will alſo, like a Spring, be <lb></lb>ſtill endeavouring to ſtretch it ſelf out <lb></lb>again. </s> <s>For though both theſe Haires, <lb></lb>and the Aerial Corpuſcles to which we <lb></lb>liken them, do eaſily yield to externall <lb></lb>preſſures; yet each of them (by vertue of <lb></lb>its ſtructure) is endow'd with a Power or <lb></lb>Principle of ſelf-Dilatation; by vertue <lb></lb>whereof, though the hairs may by a Mans <lb></lb>hand be bent and crouded cloſer together, <lb></lb>and into a narrower room then ſuits beſt <lb></lb>with the nature of the Body: Yet whil'ſt <lb></lb>the compreſſion laſts, there is in the fleece <lb></lb>they compoſe an endeavour outwards, <lb></lb>whereby it continually thruſts againſt the <lb></lb>hand that oppoſes its Expanſion. </s> <s>And <lb></lb>upon the removall of the external preſ<lb></lb>ſure, by opening the hand more or leſs, the <lb></lb>compreſſed Wooll does, as it were, ſpon<lb></lb>taneouſly expand or diſplay it ſelf towards <pb xlink:href="013/01/064.jpg" pagenum="24"></pb>the recovery of its former more looſe and <lb></lb>free condition, till the Fleece have ei<lb></lb>ther regain'd its former Dimenſions, or <lb></lb>at leaſt, approach'd them as near as the <lb></lb>compreſſing hand (perchance not quite <lb></lb>open'd) will permit. </s> <s>This Power of <lb></lb>ſelf-Dilatation, is ſomewhat more conſpi<lb></lb>cuous in a dry Spunge compreſſ'd, then <lb></lb>in a Fleece of Wooll. </s> <s>But yet we ra<lb></lb>ther choſe to imploy the latter, on this <lb></lb>occaſion, becauſe it is not like a Spunge, <lb></lb>an entire Body, but a number of ſlen<lb></lb>der and flexible Bodies, looſely com<lb></lb>plicated, as the Air it ſelf ſeems to <lb></lb>be. </s></p><p type="main"> <s>There is yet another way to explicate <lb></lb>the Spring of the Air, namely, by ſuppo<lb></lb>ſing with that moſt ingenious Gentleman, <lb></lb>Monſieur <emph type="italics"></emph>Des Cartes,<emph.end type="italics"></emph.end> That the Air is no<lb></lb>thing but a Congeries or heap of ſmall <lb></lb>and (for the moſt part) of flexible Parti<lb></lb>cles; of ſeveral ſizes, and of all kinde of Fi<lb></lb>gures which are raiſ'd by heat (eſpecially <lb></lb>that of the Sun) into that fluid and <lb></lb>ſubtle Etheriall Body that ſurrounds <lb></lb>the Earth; and by the reſtleſſe agi<lb></lb>tation of that Celeſtial Matter where<lb></lb>in thoſe Particles ſwim, are ſo whirl'd <pb xlink:href="013/01/065.jpg" pagenum="25"></pb>round, that each Corpuſcle endeavours <lb></lb>to beat off all others from coming within <lb></lb>the little Sphear requiſite to its motion <lb></lb>about its own Center; and (in caſe any, <lb></lb>by intruding into that Sphear ſhall op<lb></lb>poſe its free Rotation) to expell or drive <lb></lb>it away: So that according to this Do<lb></lb>ctrine, it imports very little, whether the <lb></lb>particles of the Air have the ſtructure re<lb></lb>quiſite to Springs, or be of any other <lb></lb>form (how irregular ſoever) ſince their <lb></lb>Elaſtical power is not made to depend <lb></lb>upon their ſhape or ſtructure, but upon <lb></lb>the vehement agitation, and (as it were) <lb></lb>brandiſhing motion, which they receive <lb></lb>from the fluid <emph type="italics"></emph>Ether<emph.end type="italics"></emph.end> that ſwiftly flows <lb></lb>between them, and whirling about each <lb></lb>of them (independently from the reſt) <lb></lb>not onely keeps thoſe ſlender Aërial <lb></lb>Bodies ſeparated and ſtretcht out (at leaſt, <lb></lb>as far as the Neighbouring ones will per<lb></lb>mit) which otherwiſe, by reaſon of <lb></lb>their flexibleneſs and weight, would <lb></lb>flag or curl; but alſo makes them hit <lb></lb>againſt, and knock away each other, and <lb></lb>conſequently require more room, then <lb></lb>that which if they were compreſſ'd, they <lb></lb>would take up. </s></p><pb xlink:href="013/01/066.jpg" pagenum="26"></pb><p type="main"> <s>By theſe two differing ways, my Lord, <lb></lb>may the Spring of the Air be explicated. <lb></lb></s> <s>But though the former of them be that, <lb></lb>which by reaſon of its ſeeming ſomewhat <lb></lb>more eaſie, I ſhall for the moſt part make <lb></lb>uſe of in the following Diſcourſe: yet <lb></lb>am I not willing to declare peremptorily <lb></lb>for either of them, againſt the other. </s> <s>And <lb></lb>indeed, though I have in another Treatiſe <lb></lb>endeavoured to make it probable, that the <lb></lb>returning of Elaſtical Bodies (if I may ſo <lb></lb>call them) forcibly bent, to their former <lb></lb>poſition, may be Mechanically explica<lb></lb>ted: Yet I muſt confeſs, that to deter<lb></lb>mine whether the motion of Reſtitution <lb></lb>in Bodies, proceed from this, That the <lb></lb>parts of a Body of a peculiar Structure <lb></lb>are put into motion by the bending of the <lb></lb>ſpring, or from the endeavor of ſome ſub<lb></lb>tle ambient Body, whoſe paſſage may be <lb></lb>oppoſ'd or obſtructed, or elſe it's preſſure <lb></lb>unequally reſiſted by reaſon of the new <lb></lb>ſhape or magnitude, which the bending of <lb></lb>a Spring may give the Pores of it: To <lb></lb>determine this, I ſay, ſeems to me a mat<lb></lb>ter of more difficulty, then at firſt ſight <lb></lb>one would eaſily imagine it. </s> <s>Wherefore <lb></lb>I ſhall decline medling with a ſubject, <lb></lb>which is much more hard to be explica-<pb xlink:href="013/01/067.jpg" pagenum="27"></pb>ted, then neceſſary to be ſo, by him, <lb></lb>whoſe buſineſs it is not, in this Letter, to <lb></lb>aſſign the adequate cauſe of the Spring of <lb></lb>the Air, but onely to manifeſt, That the <lb></lb>Air has a Spring, and to relate ſome of <lb></lb>its effects. </s></p><p type="main"> <s>I know not whether I need annex that, <lb></lb>though either of the above-mention'd <lb></lb>Hypotheſes, and perhaps ſome others, <lb></lb>may afford us an account plauſible enough <lb></lb>of the Air-ſpring; yet I doubt, whether <lb></lb>any of them gives us a ſufficient account <lb></lb>of its Nature. </s> <s>And of this doubt, I <lb></lb>might here mention ſome Reaſons, but <lb></lb>that, peradventure, I may (God permit<lb></lb>ting) have a fitter occaſion to ſay ſome<lb></lb>thing of it elſewhere. </s> <s>And therefore I <lb></lb>ſhould now proceed to the next Experi<lb></lb>ment, but that I think it requiſite, firſt, <lb></lb>to ſuggeſt to your Lordſhip what comes <lb></lb>into my thoughts, by way of Anſwer to <lb></lb>a plauſible Objection, which I foreſee you <lb></lb>may make againſt our propoſ'd Doctrine, <lb></lb>touching the Spring of the Air. </s> <s>For it <lb></lb>may be alleadged, that though the Air <lb></lb>were granted to conſiſt of Springy Par<lb></lb>ticles (if I may ſo ſpeak) yet thereby <lb></lb>we could onely give an account of the <lb></lb>Dilatation of the Air in Wine-Guns and <pb xlink:href="013/01/068.jpg" pagenum="28"></pb>other pneumatical Engines wherein the <lb></lb>Air has been compreſſ'd, and its Springs <lb></lb>violently bent by an apparent externall <lb></lb>force; upon the removall of which, 'tis <lb></lb>no wonder that the Air ſhould, by the <lb></lb>motion of reſtitution, expand it ſelf till <lb></lb>it have recovered its more natural dimen<lb></lb>ſions: whereas in our above-mentioned <lb></lb>firſt Experiment, and in almoſt all others <lb></lb>tryable in our Engine, it appears not <lb></lb>that any compreſſion of the Air prece<lb></lb>ded its ſpontaneous Dilatation or Expan<lb></lb>ſion of it ſelf. </s> <s>To remove this difficul<lb></lb>ty, I muſt deſire Your Lordſhip to take <lb></lb>notice, that of whatever nature the Air, <lb></lb>very remote from the Earth, may be, and <lb></lb>whatever the Schools may confidently <lb></lb>teach to the contrary, yet we have divers <lb></lb>Experiments to evince, that the Atmoſ<lb></lb>phere we live in is not (otherwiſe then <lb></lb>comparatively to more ponderous Bodies) <lb></lb>light, but heavy: And did not their <lb></lb>gravity hinder them, it appears not why <lb></lb>the ſteams of the Terraqueous Globe, of <lb></lb>which our Air in great part conſiſts, <lb></lb>ſhould not riſe much higher then the Re<lb></lb>fraction of the Sun, and other Stars <lb></lb>give men ground to think, that the At<lb></lb>moſphere, even in the judgement of thoſe <pb xlink:href="013/01/069.jpg" pagenum="29"></pb>Recent Aſtronomers, who ſeem willing <lb></lb>to enlarge its bounds as much as they dare, <lb></lb>does reach. </s></p><p type="main"> <s>But leſt you ſhould expect my ſeconding <lb></lb>this Reaſon by Experience; and leſt you <lb></lb>ſhould object, That moſt of the <expan abbr="Experi-mẽts">Experi<lb></lb>ments</expan> that have been propoſ'd to prove the <lb></lb>gravity of the Air, have been either barely <lb></lb>propoſ'd, or perhaps not accuratly try'd; I <lb></lb>am content, before I paſs further, to menti<lb></lb>on here, That I found a dry lambs-bladder <lb></lb>containing near about two thirds of a pint, <lb></lb>and compreſſ'd by a packthred tyed about <lb></lb>it, to looſe a grain and the eighth part of <lb></lb>a grain of its former weight, by the receſs <lb></lb>of the Air upon my having prickt it: And <lb></lb>this with a pair of Scales, which when the <lb></lb>full Bladder and the correſpondent weight <lb></lb>were in it, would manifeſtly turn either <lb></lb>way with the 32 part of a grain. </s> <s>And if <lb></lb>it be further objected, That the Air in <lb></lb>the Bladder was violently compreſſ'd by <lb></lb>the Pack-thred and the ſides of the <lb></lb>Bladder, we might probably (to wave <lb></lb>prolix anſwers) be furniſh'd with a Re<lb></lb>ply, by ſetting down the differing weight <lb></lb>of our Receiver, when empty'd and when <lb></lb>full of uncompreſſ'd Air, if we could here <lb></lb>procure ſcales fit for ſo nice an experiment; <pb xlink:href="013/01/070.jpg" pagenum="30"></pb>ſince we are informed, that in the <emph type="italics"></emph>German<emph.end type="italics"></emph.end><lb></lb>Experiment, commended at the begin<lb></lb>ning of this Letter, the Ingenious Tryers <lb></lb>of it found, That their Glaſs Veſſel, of <lb></lb>the capacity of 32 meaſures, was lighter <lb></lb>when the Air had been drawn out of it, <lb></lb>then before, by no leſs then one ounce <lb></lb>and (3/10) that is, an ounce and very near a <lb></lb>third: But of the gravity of the Air, we <lb></lb>may elſewhere have occaſion to make fur<lb></lb>ther mention. </s></p><p type="main"> <s>Taking it then for granted that the Air <lb></lb>is not deyoid of weight, it will not be <lb></lb>uneaſie to conceive, that that part of the <lb></lb>Atmoſphere wherein we live, being the <lb></lb>lower part of it, the Corpuſcles that com<lb></lb>poſe it, are very much compreſſ'd by the <lb></lb>weight of all thoſe of the like nature that <lb></lb>are directly over them, that is, of all the <lb></lb>Particles of Air, that being pil'd up up<lb></lb>on them, reach to the top of the Atmoſ<lb></lb>phere. </s> <s>And though the height of this <lb></lb>Atmoſphere, according to the famous <lb></lb><emph type="italics"></emph>Kepler,<emph.end type="italics"></emph.end> and ſome others, ſcarce exceeds <lb></lb>eight common miles; yet other eminent <lb></lb>and later Aſtronomers, would promote <lb></lb>the confines of the Atmoſphere, to ex<lb></lb>ceed ſix or ſeven times that number of <lb></lb>miles. </s> <s>And the diligent and learned <pb xlink:href="013/01/071.jpg" pagenum="31"></pb><emph type="italics"></emph>Riviolo<emph.end type="italics"></emph.end> makes it probable, that the At<lb></lb>moſphere may, at leaſt in divers places, be <lb></lb>at leaſt 50 miles high. </s> <s>So that according to <lb></lb>a moderate eſtimate of the thickneſs of <lb></lb>the Atmoſphere, we may well ſuppoſe, <lb></lb>that a Column of Air, of many miles in <lb></lb>height, leaning upon ſome ſpringy Cor<lb></lb>puſcles of Air here below, may have <lb></lb>weight enough to bend their little ſprings, <lb></lb>and keep them bent: As, to reſume our <lb></lb>former compariſon, if there were fleeces of <lb></lb>Wooll pil'd up to a mountainous height <lb></lb>upon one another, the Hairs that com<lb></lb>poſe the lowermoſt locks which ſupport <lb></lb>the reſt, would, by the weight of all the <lb></lb>Wool above them, be as well ſtrongly <lb></lb>compreſſed, as if a man ſhould ſqueeze <lb></lb>them together in his hands, or imploy any <lb></lb>ſuch other moderate force to compreſs <lb></lb>them. </s> <s>So that we need not wonder, that <lb></lb>upon the taking off the incumbent Air <lb></lb>from any parcel of the Atmoſphere here <lb></lb>below, the Corpuſcles, whereof that un<lb></lb>dermoſt Air conſiſts, ſhould diſplay them<lb></lb>ſelves, and take up more room then be<lb></lb>fore. </s></p><p type="main"> <s>And if it be objected, That in Water, <lb></lb>the weight of the upper and of the lower <lb></lb>part is the ſame: I anſwer, That beſides <pb xlink:href="013/01/072.jpg" pagenum="32"></pb>that it may be well doubted whether the <lb></lb>obſervation, by reaſon of the great diffi<lb></lb>culty have been exactly made, there is a <lb></lb>manifeſt diſparity betwixt the Air and <lb></lb>Water: For I have not found, that upon <lb></lb>an Experiment purpoſely made, (and in <lb></lb>another Treatiſe Recorded) that Water <lb></lb>will ſuffer any conſiderable compreſſion; <lb></lb>whereas we may obſerve in Wind-Guns <lb></lb>(to mention now no other Engines) that <lb></lb>the Air will ſuffer it ſelf to be crouded in<lb></lb>to a comparatively very little room; in <lb></lb>ſo much, that a very diligent Examiner <lb></lb>of the <emph type="italics"></emph>Phænomena<emph.end type="italics"></emph.end> of Wind-Guns would <lb></lb>have us believe, that in one of them, by <lb></lb>condenſation, he reduc'd the Air into a <lb></lb>ſpace at leaſt eight times narrower then it <lb></lb>before poſſeſt. </s> <s>And to this, if we adde <lb></lb>a noble <emph type="italics"></emph>Phænomenon<emph.end type="italics"></emph.end> of the Experiment <lb></lb><emph type="italics"></emph>De Vacuo;<emph.end type="italics"></emph.end> theſe things put together, may <lb></lb>for the preſent ſuffice to countenance our <lb></lb>Doctrine. </s> <s>For that noble Experimenter, <lb></lb>Monſieur <emph type="italics"></emph>Paſcal<emph.end type="italics"></emph.end> (the Son) had the com<lb></lb>mendable Curioſity to cauſe the <emph type="italics"></emph>Torri<lb></lb>cellian<emph.end type="italics"></emph.end> Experiment to be try'd at the foot, <lb></lb>about the middle, and at the top of that <lb></lb>high Mountain (in <emph type="italics"></emph>Auvergne,<emph.end type="italics"></emph.end> if I miſtake <lb></lb>not) commonly call'd <emph type="italics"></emph>Le Puy de Domme;<emph.end type="italics"></emph.end><lb></lb>whereby it was found, That the <emph type="italics"></emph>Mercury<emph.end type="italics"></emph.end><pb xlink:href="013/01/073.jpg" pagenum="33"></pb>in the Tube fell down lower, about three <lb></lb>inches, at the top of the Mountain then <lb></lb>at the bottom. </s> <s>And a Learned Man a <lb></lb>while ſince inform'd me, That a great <lb></lb><emph type="italics"></emph>Virtuoſo,<emph.end type="italics"></emph.end> friend to us both, has, with not <lb></lb>unlike ſucceſs, tryed the ſame Experi<lb></lb>ment in the lower and upper parts of a <lb></lb>Mountain in the Weſt of <emph type="italics"></emph>England:<emph.end type="italics"></emph.end> Of <lb></lb>which, the reaſon ſeems manifeſtly enough <lb></lb>to be this, That upon the tops of high <lb></lb>Mountains, the Air which bears againſt <lb></lb>the reſtagnant Quick-ſilver, is leſs preſſ'd <lb></lb>by the leſs ponderous incumbent Air; and <lb></lb>conſequently is not able totally to hinder <lb></lb>the deſcent of ſo tall and heavy a Cylin<lb></lb>der of Quick-ſilver, as at the bottom of <lb></lb>ſuch Mountains did but maintain an <emph type="italics"></emph>Æqui<lb></lb>librium<emph.end type="italics"></emph.end> with the incumbent Atmoſphere. </s></p><p type="main"> <s>And if it be yet further Objected a<lb></lb>gainſt what hath been propoſ'd touching <lb></lb>the compactneſs and preſſure of the Infe<lb></lb>rior Air; That we finde this very Air to <lb></lb>yield readily to the motion of little Flies, <lb></lb>and even to that of Feathers, and ſuch o<lb></lb>ther light and weak Bodies; which ſeems <lb></lb>to argue, that the particles of our Air are <lb></lb>not ſo compreſſ'd as we have repreſented <lb></lb>them, eſpecially, ſince by our former <lb></lb>Experiment it appears, that the Air rea-<pb xlink:href="013/01/074.jpg" pagenum="34"></pb>dily dilated it ſelf downward, from the <lb></lb>Receiver into the Pump, when 'tis plain, <lb></lb>that it is not the incumbent Atmoſphere, <lb></lb>but onely the ſubjacent Air in the braſs <lb></lb>Cylinder that has been remov'd: If this, <lb></lb>I ſay, be objected, we may reply, That <lb></lb>when a man ſqueezes a Fleece of Wool in <lb></lb>his hand, he may feel that the Wool in<lb></lb>ceſſantly bears againſt his hand, as that <lb></lb>which hinders the hairs it conſiſts of, to <lb></lb>recover their former and more natural ex<lb></lb>tent. </s> <s>So each parcel of the Air about the <lb></lb>Earth, does conſtantly endeavour to thruſt <lb></lb>away all thoſe contiguous Bodies, whe<lb></lb>ther Aërial or more groſs, that keep <lb></lb>them bent, and hinder the expanſion of <lb></lb>its parts, which will dilate themſelves or <lb></lb>flie abroad towards that part, whether up<lb></lb>wards or downwards, where they finde <lb></lb>their attempted Dilatation of themſelves <lb></lb>leſs reſiſted by the neihgboring Bodies. <lb></lb></s> <s>Thus the Corpuſcles of that Air we have <lb></lb>been all this while ſpeaking of, being un<lb></lb>able, by reaſon of their weight, to aſcend <lb></lb>above the Convexity of the Atmoſphere, <lb></lb>and by reaſon of the reſiſtance of the ſur<lb></lb>face of the Earth and Water, to fall down <lb></lb>lower, they are forced, by their own gra<lb></lb>vity and this reſiſtance, to expand and <pb xlink:href="013/01/075.jpg" pagenum="35"></pb>diffuſe themſelves about the Terreſtial <lb></lb>Globe; whereby it comes to paſs, that <lb></lb>they muſt as well preſs the contiguous <lb></lb>Corpuſcles of Air that on either ſide op<lb></lb>poſe their Dilatation, as they muſt preſs <lb></lb>upon the ſurface of the Earth, and, as it <lb></lb>were recoyling thence, endeavor to thruſt <lb></lb>away thoſe upper particles of Air that <lb></lb>lean upon them. </s></p><p type="main"> <s>And as for the eaſie yielding of the Air <lb></lb>to the Bodies that move in it, if we con<lb></lb>ſider that the Corpuſcles whereof it con<lb></lb>ſiſts, though of a ſpringy nature, are yet <lb></lb>ſo very ſmall, as to make up (which 'tis <lb></lb>manifeſt they doe) a fluid Body, it will <lb></lb>not be difficult to conceive, that in the <lb></lb>Air, as in other Bodies that are fluid, the <lb></lb>little Bodies it conſiſts of are in an almoſt <lb></lb>reſtleſs motion, whereby they become <lb></lb>(as we have more fully diſcourſed in ano<lb></lb><arrow.to.target n="marg3"></arrow.to.target><lb></lb>ther Treatiſe) very much diſpoſed to <lb></lb>yield to other Bodies, or eaſie to be diſ<lb></lb>plac'd by them, and that the ſame Cor<lb></lb>puſcles are likewiſe ſo variouſly mov'd, as <lb></lb>they are intire Corpuſcles, that if ſome <lb></lb>ſtrive to puſh a Body plac'd among them <lb></lb>towards the right hand (for inſtance) <lb></lb>others, whoſe motion has an oppoſite de<lb></lb>termination, as ſtrongly thruſt the ſame <pb xlink:href="013/01/076.jpg" pagenum="36"></pb>Body towards the left; whereby neither <lb></lb>of them proves able to move it out of <lb></lb>its place, the preſſure on all hands being <lb></lb>reduced as it were to an <emph type="italics"></emph>Æquilibrium:<emph.end type="italics"></emph.end> ſo <lb></lb>that the Corpuſcles of the Air muſt be as <lb></lb>well ſometimes conſidered under the no<lb></lb>tion of little Springs, which remaining <lb></lb>bent, are in their entire bulk tranſported <lb></lb>from place to place; as under the notion <lb></lb>of Springs diſplaying themſelves, whoſe <lb></lb>parts flie abroad whilſt as to their entire <lb></lb>bulk they ſcarce change place: As the <lb></lb>two ends of a Bow, ſhot off, fly from one <lb></lb>another, whereas the Bow it ſelf may be <lb></lb>held faſt in the Archers hand; and that it <lb></lb>is the equal preſſure of the Air on all ſides <lb></lb>upon the Bodies that are in it, which cau<lb></lb>ſes the eaſie Ceſſion of its parts, may be <lb></lb>argu'd from hence: That if by the help <lb></lb>of our Engine the Air be but in great <lb></lb>part, though not totally drawn away <lb></lb>from one ſide of a Body without being <lb></lb>drawn away from the other; he that ſhall <lb></lb>think to move that Body too and fro, as <lb></lb>eaſily as before, will finde himſelf much <lb></lb>miſtaken. </s></p><p type="margin"> <s><margin.target id="marg3"></margin.target><emph type="italics"></emph>In a Diſ<lb></lb>courſe <lb></lb>touching <lb></lb>ſluidity <lb></lb>and firm<lb></lb>neſs.<emph.end type="italics"></emph.end></s></p><p type="main"> <s>In verification of which we will, to di<lb></lb>vert your Lordſhip a little, mention here <lb></lb>a <emph type="italics"></emph>Phænomenon<emph.end type="italics"></emph.end> of our Engine, which even <pb xlink:href="013/01/077.jpg" pagenum="37"></pb>to divers ingenious perſons has at firſt <lb></lb>ſight ſeem'd very wonderful. </s></p><p type="main"> <s>THe thing that is wont to be admired, <lb></lb><arrow.to.target n="marg4"></arrow.to.target><lb></lb>and which may paſs for our ſecond <lb></lb>Experiment is this, That if, when the <lb></lb>Receiver is almoſt empty, a By-ſtander <lb></lb>be deſired to lift up the braſs Key (former<lb></lb>ly deſcribed as a ſtopple in the braſs Co<lb></lb>ver) he will finde it a very difficult thing <lb></lb>to do ſo, if the Veſſel be well exhauſted; <lb></lb>and even when but a moderate quantity of <lb></lb>Air has been drawn out, he will, when he <lb></lb>has lifted it up a little, ſo that it is ſome<lb></lb>what looſe from the ſides of the lip or <lb></lb>ſocket, which (with the help of a little <lb></lb>oyl) it exactly filled before, he will (I ſay) <lb></lb>finde it ſo difficult to be lifted up, that <lb></lb>he will imagine there is ſome great weight <lb></lb>faſtned to the bottom of it. </s> <s>And if (as <lb></lb>ſometimes has been done for merriment) <lb></lb>onely a Bladder be tyed to it, it is plea<lb></lb>ſant to ſee how men will marvail that ſo <lb></lb>light a Body, filled at moſt but with Air, <lb></lb>ſhould ſo forcibly draw down their hand <lb></lb>as if it were fill'd with ſome very ponder<lb></lb>ous thing: whereas the cauſe of this pret<lb></lb>ty <emph type="italics"></emph>Phænomenon<emph.end type="italics"></emph.end> ſeems plainly enough to <pb xlink:href="013/01/078.jpg" pagenum="38"></pb>be onely this, That the Air in the Recei<lb></lb>ver, being very much dilated, its Spring <lb></lb>muſt be very much weakn'd, and conſe<lb></lb>quently it can but faintly preſs up the <lb></lb>lower end of the ſtopple, whereas the <lb></lb>Spring of the external Air being no way <lb></lb>debilitated, he that a little lifts up the <lb></lb>ſtopple muſt with his hand ſupport a preſ<lb></lb>ſure equal to the diſproportion betwixt <lb></lb>the force of the internal expanded Air, and <lb></lb>that of the Atmoſphere incumbent upon <lb></lb>the upper part of the ſame key or ſtopple: <lb></lb>And ſo men being unuſ'd to finde any re<lb></lb>ſiſtance, in lifting things up, from the <lb></lb>free Air above them, they are forward to <lb></lb>conclude that that which depreſſes their <lb></lb>hands muſt needs be ſome weight, though <lb></lb>they know not where plac'd, drawing be<lb></lb>neath it. </s></p><p type="margin"> <s><margin.target id="marg4"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 2.</s></p><p type="main"> <s>And that we have not miſ-aſſign'd the <lb></lb>cauſe of this <emph type="italics"></emph>Phænomenon<emph.end type="italics"></emph.end> ſeems evident <lb></lb>enough by this; That as Air is ſuffer<lb></lb>ed by little and little to get into the Re<lb></lb>ceiver, the weight that a man fancies his <lb></lb>hand ſupports is manifeſtly felt to decreaſe <lb></lb>more and more, the internal Air by this <lb></lb>recruit approaching more to an <emph type="italics"></emph>Æquili<lb></lb>brium<emph.end type="italics"></emph.end> with the external, till at length the <lb></lb>Receiver growing again full of Air, the <pb xlink:href="013/01/079.jpg" pagenum="39"></pb>ſtopple may be lifted up without any dif<lb></lb>ficulty at all. </s></p><p type="main"> <s>By ſeveral other of the Experiments <lb></lb>afforded us by our Engine, the ſame no<lb></lb>tion of the great and equal preſſure of the <lb></lb>free Air upon the Bodies it environs, <lb></lb>might be here manifeſted, but that we <lb></lb>think it not ſo fit to anticipate ſuch Ex<lb></lb>periments: And therefore ſhall rather <lb></lb>employ a few lines to clear up a difficulty <lb></lb>touching this matter, which we have ob<lb></lb>ſerv'd to have troubled ſome even of the <lb></lb>Philoſophical and Mathematical Specta<lb></lb>tors of our Engine, who have wonder'd <lb></lb>that we ſhould talk of the Air exquiſitely <lb></lb>ſhut up in our Receiver, as if it were all <lb></lb>one with the preſſure of the Atmoſphere; <lb></lb>whereas the thick and cloſe body of the <lb></lb>Glaſs, wholly impervious to the Air, does <lb></lb>manifeſtly keep the incumbent Pillar of <lb></lb>the Atmoſphere from preſſing in the leaſt <lb></lb>upon the Air within the Glaſs, which it <lb></lb>can no where come to touch. </s> <s>To eluci<lb></lb>date a little this matter, let us conſider, <lb></lb>That if a man ſhould take a fleece of <lb></lb>Wool, and having firſt by compreſſing it <lb></lb>in his hand reduc'd it into a narrower com<lb></lb>paſs, ſhould nimbly convey and ſhut it <lb></lb>cloſe up into a Box juſt fit for it, though <pb xlink:href="013/01/080.jpg" pagenum="40"></pb>the force of his hand would then no lon<lb></lb>ger bend thoſe numerous ſpringy Body's <lb></lb>that compoſe the Fleece, yet they would <lb></lb>continue as ſtrongly bent as before, be<lb></lb>cauſe the Box they are incloſ'd in would <lb></lb>as much reſiſt their re-expanding of <lb></lb>themſelves, as did the hand that put them <lb></lb>in. </s> <s>For thus we may conceive, that the <lb></lb>Air being ſhut up, when its parts are bent <lb></lb>by the whole weight of the incumbent <lb></lb>Atmoſphere, though that weight can no <lb></lb>longer lean upon it, by reaſon it is kept <lb></lb>off by the Glaſs, yet the Corpuſcles of <lb></lb>the Air within that Glaſs continue as <lb></lb>forcibly bent as they were before their in<lb></lb>cluſion, becauſe the ſides of the Glaſs <lb></lb>hinder them from diſplaying or ſtretch<lb></lb>ing out themſelves. </s> <s>And if it be ob<lb></lb>jected that this is unlikely, becauſe ev'n <lb></lb>Glaſs bubles, ſuch as are wont to be <lb></lb>blown at the flame of a Lamp, exceeding <lb></lb>thin and Hermetically ſeal'd will not <lb></lb>break; whereas it cannot be imagin'd <lb></lb>that ſo thin a Priſon of Glaſs could re<lb></lb>ſiſt the Elaſtical force of all the included <lb></lb>Air, if that Air were ſo compreſſ'd as we <lb></lb>ſuppoſe. </s> <s>It may be eaſily reply'd, That <lb></lb>the preſſure of the inward Air againſt the <lb></lb>Glaſs, is countervail'd by the equal preſ-<pb xlink:href="013/01/081.jpg" pagenum="41"></pb>ſure of the outward againſt the ſame Glaſs. <lb></lb></s> <s>And we ſee in bubles, that by reaſon of <lb></lb>this an exceeding thin film of Water is <lb></lb>often able, for a good while, to hinder the <lb></lb>eruption of a pretty quantity of Air. </s> <s>And <lb></lb>this may be alſo more conſpicuous in <lb></lb>thoſe great Spherical bubles that boyes <lb></lb>ſometimes blow with Water, to which <lb></lb>Sope has given a Tenacity. </s> <s>But that, if the <lb></lb>preſſure of the ambient Air were remov'd, <lb></lb>the internal Air may be able to break <lb></lb>thicker Glaſſes then thoſe lately men<lb></lb>tion'd, will appear by ſome of the follow<lb></lb>ing Experiments; to which we ſhall there<lb></lb>fore now haſten, having, I fear, been but <lb></lb>too prolix in this Excurſion, though we <lb></lb>thought it not amiſs to annex to our firſt <lb></lb>Experiments ſome general Conſiderati<lb></lb>ons touching the Spring of the Air, be<lb></lb>cauſe (this Doctrine being yet a ſtranger <lb></lb>to the Schools) not onely we finde not <lb></lb>the thing it ſelf to be much taken notice <lb></lb>of; but of thoſe few that have heard of it, <lb></lb>the greater part have been forward to re<lb></lb>ject it, upon a miſtaken Perſwaſion, that <lb></lb>thoſe <emph type="italics"></emph>Phænomena<emph.end type="italics"></emph.end> are the effects of natures <lb></lb>abhorrency of a <emph type="italics"></emph>Vacuum,<emph.end type="italics"></emph.end> which ſeem to <lb></lb>be more fitly aſcribeable to the weight <lb></lb>and Spring of the Air. </s></p><pb xlink:href="013/01/082.jpg" pagenum="42"></pb><p type="main"> <s>WE will now proceed to obſerve that <lb></lb><arrow.to.target n="marg5"></arrow.to.target><lb></lb>though, by the help of the handle, <lb></lb>the Sucker be eaſily drawn down to the <lb></lb>bottom of the Cylinder; yet, without <lb></lb>the help of that Leaver, there would be <lb></lb>required to the ſame effect, a force or <lb></lb>weight great enough to ſurmount the <lb></lb>preſſure of the whole Atmoſphere: Since <lb></lb>otherwiſe the Air would not be driven out <lb></lb>of its place, when none is permitted to <lb></lb>ſucceed into the place deſerted by the <lb></lb>Sucker. </s> <s>This ſeems evident, from the <lb></lb>known <emph type="italics"></emph>Torricellian<emph.end type="italics"></emph.end> Experiment, in which, <lb></lb>if the inverted Tube of <emph type="italics"></emph>Mercury<emph.end type="italics"></emph.end> be but <lb></lb>25 Digits high, or ſomewhat more, the <lb></lb>Quick-ſilver will not fall but remain ſuſ<lb></lb>pended in the Tube; becauſe it cannot <lb></lb>preſs the ſubjacent <emph type="italics"></emph>Mercury<emph.end type="italics"></emph.end> with ſo great <lb></lb>a force, as does the incumbent Cylinder <lb></lb>of the Air reaching thence to the top of <lb></lb>the Atmoſphere: Whereas, if the Cy<lb></lb>linder of <emph type="italics"></emph>Mercury<emph.end type="italics"></emph.end> were three or four digits <lb></lb>longer, it would over-power that of the <lb></lb>external Air, and run out into the Veſſel'd <lb></lb><emph type="italics"></emph>Mercury,<emph.end type="italics"></emph.end> till the two Cylinders came to <lb></lb>an <emph type="italics"></emph>Æquilibrium,<emph.end type="italics"></emph.end> and no further. </s> <s>Hence <lb></lb>we need not wonder, that though the <pb xlink:href="013/01/083.jpg" pagenum="43"></pb>Sucker move eaſily enough up and down <lb></lb>in the Cylinder by the help of the <emph type="italics"></emph>Manu<lb></lb>brium;<emph.end type="italics"></emph.end> yet if the <emph type="italics"></emph>Manubrium<emph.end type="italics"></emph.end> be taken off, <lb></lb>it will require & conſiderable ſtrength to <lb></lb>move it either way. </s> <s>Nor will it ſeem <lb></lb>ſtrange, that if, when the Valve and <lb></lb>Stop-cock are well ſhut, you draw down <lb></lb>the Sucker, and then let go the <emph type="italics"></emph>Manubri<lb></lb>um;<emph.end type="italics"></emph.end> the Sucker will, as it were of it ſelf, <lb></lb>re-aſcend to the top of the Cylinder, ſince <lb></lb>the ſpring of the external Air findes no<lb></lb>thing to reſiſt its preſſing up the Sucker. <lb></lb></s> <s>And for the ſame reaſon, when the Re<lb></lb>ceiver is almoſt evacuated, though, ha<lb></lb>ving drawn down the Sucker, you open <lb></lb>the way from the Receiver to the Cylin<lb></lb>der, and then intercept that way again by <lb></lb>returning the Key; the Sucker will, up<lb></lb>on the letting go the <emph type="italics"></emph>Manubrium,<emph.end type="italics"></emph.end> be <lb></lb>forcibly carried up almoſt to the top of <lb></lb>the Cylinder: Becauſe the Air within the <lb></lb>Cylinder, being equally dilated and weak<lb></lb>ned with that of the Glaſs, is unable to <lb></lb>withſtand the preſſure of the external Air, <lb></lb>till it be driven into ſo little ſpace, that <lb></lb>there is an <emph type="italics"></emph>Æquilibrium<emph.end type="italics"></emph.end> betwixt its force <lb></lb>and that of the Air without. </s> <s>And con<lb></lb>gruouſly hereunto we finde, that in this <lb></lb>caſe, the Sucker is drawn down with little <pb xlink:href="013/01/084.jpg" pagenum="44"></pb>leſs difficulty, then if the Cylinder, be<lb></lb>ing devoid of Air, the Stop-cock were <lb></lb>exactly ſhut: We might take notice of <lb></lb>ſome other things, that depend upon the <lb></lb>Fabrick of our Engine it ſelf; but to ſhun <lb></lb>prolixity, we will, in this place, content <lb></lb>our ſelves to mention one of them, which <lb></lb>ſeems to be of greater moment then the <lb></lb>reſt, and it is this; that when the Sucker <lb></lb>has been impell'd to the top of the Cylin<lb></lb>der, and the Valve is ſo carefully ſtopp'd, <lb></lb>that there is no Air left in the Cylinder a<lb></lb>bove the Sucker: If then the Sucker be <lb></lb>drawn to the lower part of the Cylinder, <lb></lb>he that manages the Pump findes not any <lb></lb>ſenſibly greater difficulty to depreſs the <lb></lb>Sucker, when it is nearer the bottom of the <lb></lb>Cylinder, then when it is much further off. <lb></lb></s> <s>Which circumſtance we therefore think fit <lb></lb>to take notice of, becauſe an eminent Mo<lb></lb>dern Naturaliſt hath taught, that, when the <lb></lb>Air is ſucked out of a Body, the violence <lb></lb>wherewith it is wont to ruſh into it again, <lb></lb>as ſoon as it is allow'd to re-enter, pro<lb></lb>ceeds mainly from this; That the preſſure <lb></lb>of the ambient Air is ſtrengthned upon <lb></lb>the acceſſion of the Air ſuck'd out; which, <lb></lb>to make it ſelf room, forces the neighbor<lb></lb>ing Air to a violent-ſubingreſſion oſ its <lb></lb>parts: which, iſ it were true, he that draws <pb xlink:href="013/01/085.jpg" pagenum="45"></pb>down the Sucker, would finde the reſiſt<lb></lb>ance of the external Air increaſ'd as he <lb></lb>draws it lower, more of the diſplaced Air <lb></lb>being thruſt into it to compreſs it. </s> <s>But, by <lb></lb>what has been diſcourſ'd upon the firſt <lb></lb>Experiment, it ſeems more probable, that <lb></lb>without any ſuch ſtrengthning of the preſ<lb></lb>ſure of the outward Air, the taking quite <lb></lb>away or the debilitating of the reſiſtance <lb></lb>from within, may ſuffice to produce the <lb></lb>effects under conſideration. </s> <s>But this will <lb></lb>perhaps be illuſtrated by ſome or other of <lb></lb>our future Experiments, and therefore <lb></lb>ſhall be no longer inſiſted on here. </s></p><p type="margin"> <s><margin.target id="marg5"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 3.</s></p><p type="main"> <s>HAving thus taken notice of ſome of <lb></lb><arrow.to.target n="marg6"></arrow.to.target><lb></lb>the conſtant <emph type="italics"></emph>Phænomena<emph.end type="italics"></emph.end> of our En<lb></lb>gine it ſelf, let us now proceed to the Ex<lb></lb>periments tryable in it. </s></p><p type="margin"> <s><margin.target id="marg6"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 4.</s></p><p type="main"> <s>We took then a Lambs Bladder large, <lb></lb>well dry'd, and very limber, and leaving in <lb></lb>it about half as much Air as it could con<lb></lb>tain, we cauſ'd the neck of it to be ſtrong<lb></lb>ly ty'd, ſo that none of the included Air, <lb></lb>though by preſſure, could get out. </s> <s>This <lb></lb>Bladder being convey'd into the Receiver, <lb></lb>and the Cover luted on, the Pump <lb></lb>was ſet awork, and after two or three <lb></lb>exſuctions of the ambient Air (where<lb></lb>by the Spring of that which remain'd in <pb xlink:href="013/01/086.jpg" pagenum="46"></pb>the Glaſs was weaken'd) the Impriſon'd <lb></lb>Air began to ſwell in the Bladder, and as <lb></lb>more and more of the Air in the Recei<lb></lb>ver was, from time to time, drawn out; ſo <lb></lb>did that in the Bladder more and more ex<lb></lb>pand it ſelf, and diſplay the folds of the <lb></lb>formerly flaccid Bladder: ſo that before we <lb></lb>had exhauſted the Receiver near ſo much <lb></lb>as we could, the Bladder appear'd as full <lb></lb>and ſtretched, as if it had been blown up <lb></lb>with a Quill. </s></p><p type="main"> <s>And that it may appear that this plump<lb></lb>neſs of the Bladder proceeded from the <lb></lb>ſurmounting of the debilitated Spring of <lb></lb>the ambient Air remaining in the Veſſel, <lb></lb>by the ſtronger Spring of the Air remain<lb></lb>ing in the Bladder; we Return'd the Key <lb></lb>of the Stop-cock, and by degrees allow'd <lb></lb>the external Air to return into the Recei<lb></lb>ver: Whereupon it happen'd, as was ex<lb></lb>pected, that as the Air came in from with<lb></lb>out, the diſturb'd Air in the Bladder, was <lb></lb>proportionably compreſſ'd into a narrow<lb></lb>er room, and the ſides of the Bladder <lb></lb>grew flaccid, till the Receiver having re<lb></lb>admitted its wonted quantity of Air, the <lb></lb>Bladder appear'd as full of wrinkles and <lb></lb>cavities as before. </s></p><pb xlink:href="013/01/087.jpg" pagenum="47"></pb><p type="main"> <s>This Experiment is much of the ſame <lb></lb>nature with that which was ſome years <lb></lb>agoe ſaid to be made by that eminent Ge<lb></lb>ometrician Monſieur <emph type="italics"></emph>Roberval,<emph.end type="italics"></emph.end> with a <lb></lb>Carps Bladder empty'd and convey'd into <lb></lb>a Tube, wherein the Experiment <emph type="italics"></emph>De Va<lb></lb>cuo<emph.end type="italics"></emph.end> was afterwards try'd, which ingeni<lb></lb>ous Experiment of his juſtly deſerves the <lb></lb>thanks of thoſe that have been, or ſhall be <lb></lb>ſolicitous to diſcover the nature of the <lb></lb>Air. </s></p><p type="main"> <s>But to return to our Experiment, we <lb></lb>may take notice of this Circumſtance in <lb></lb>it, That after the Receiver has been in <lb></lb>ſome meaſure empty'd, the Bladder do's, <lb></lb>at each exſuction, ſwell much more con<lb></lb>ſpicuouſly then it did at any of the firſt <lb></lb>Exſuctions; inſomuch that towards the <lb></lb>end of the pumping, not onely a great <lb></lb>fold or cavity in the ſurface of the Blad<lb></lb>der may be made, even by the ſtretching <lb></lb>of the inward ſelf-expanding Air: But <lb></lb>we have ſometimes ſeen, upon the turn<lb></lb>ing of the Key to let the ambient Air <lb></lb>paſs out of the Receiver into the Cylin<lb></lb>der, we have ſeen (I ſay) the Air in the <lb></lb>Bladder ſuddenly expand it ſelf ſo much <lb></lb>and ſo briskly, that it manifeſtly lifted up <lb></lb>ſome light Bodies that lean'd upon it, <pb xlink:href="013/01/088.jpg" pagenum="48"></pb>and ſeem'd to lift up the Bladder it <lb></lb>ſelf. </s></p><p type="main"> <s>Now becauſe it has by very Learned <lb></lb>Men been doubted whether the ſwelling <lb></lb>of the Bladder may not have proceeded <lb></lb>from the Dilatation of the included Air, <lb></lb>but from the Texture of the Fibres, <lb></lb>which, being wont to keep the Bladder <lb></lb>extended when the Animal to whom it <lb></lb>belong'd was alive, may be ſuppoſ'd in <lb></lb>our Experiment to have return'd, like ſo <lb></lb>many Springs to their wonted extent, up<lb></lb>on the removal of the Ambient Air that <lb></lb>compreſſ'd and bent them: becauſe this, <lb></lb>I ſay, has been doubted, we thought fit <lb></lb>to make this further tryall. </s></p><p type="main"> <s>We let down into the Receiver with <lb></lb>the fore-mentioned Bladder two other <lb></lb>much ſmaller, and of the ſame kinde of <lb></lb>Animal; the one of theſe was not ty'd <lb></lb>up at the neck that there might be liberty <lb></lb>left to the Air that was not ſqueez'd out <lb></lb>(which might amount to about a fifth <lb></lb>part of what the Bladder held before) to <lb></lb>paſs out into the Receiver: The other had <lb></lb>the ſides of it ſtretch'd out and preſſ'd to<lb></lb>gether, almoſt into the form of a Cup, <lb></lb>that they might intercept the leſs Air be<lb></lb>twixt them, and then was ſtrongly ty'd <pb xlink:href="013/01/089.jpg" pagenum="49"></pb>up at the neck: This done, and the Air <lb></lb>being in ſome meaſure ſuck'd out of the <lb></lb>Pneumatical Glaſs (if I may ſo call it) <lb></lb>the Bladder, mention'd at the beginning <lb></lb>of our Experiment, appear'd extended e<lb></lb>very way to its full Dimenſions; whereas <lb></lb>neither of the two others did remarkably <lb></lb>ſwell, and that whoſe neck was not ty'd <lb></lb>ſeem'd very little, if at all leſs wrinkl'd <lb></lb>then when it was put in. </s></p><p type="main"> <s>We made likewiſe a ſtrong Ligature a<lb></lb>bout the middle of a long Bladder part<lb></lb>ly empty'd, and upon the drawing the <lb></lb>Air out of the Receiver, could obſerve <lb></lb>no ſuch ſwelling betwixt the Ligature and <lb></lb>the Neck of the Bladder, which had been <lb></lb>purpoſely left open, as betwixt the ſame <lb></lb>Ligature and the bottom of the Bladder, <lb></lb>whence the included Air could no way <lb></lb>get out. </s></p><p type="main"> <s>But a further and ſufficient manifeſtati<lb></lb>on whence the intumeſſence of the Blad<lb></lb>der proceeds, may be deduc'd from the <lb></lb>following Experiment. </s></p><p type="main"> <s>TO try then at once both what it was <lb></lb><arrow.to.target n="marg7"></arrow.to.target><lb></lb>that expanded the Bladder, and what <lb></lb>a powerful Spring there is ev'n in the Air <pb xlink:href="013/01/090.jpg" pagenum="50"></pb>we are wont to think uncompreſſ'd, we <lb></lb>cauſ'd a Bladder dry, well ty'd and blown <lb></lb>moderately full, to be hung in the Recei<lb></lb>ver by one end of a ſtring, whoſe other <lb></lb>end was faſtned to the inſide of the Co<lb></lb>ver: and upon drawing out the ambient <lb></lb>Air, that preſſ'd on the Bladder; the in<lb></lb>ternal Air not finding the wonted reſiſt<lb></lb>ance, firſt ſwell'd and diſtended the Blad<lb></lb>der, and then broke it, with ſo wide and <lb></lb>crooked a rent, as if it had been forcibly <lb></lb>torn aſſunder with hands. </s> <s>After which a <lb></lb>ſecond Bladder being convey'd in, the Ex<lb></lb>periment was repeated with like ſucceſs: <lb></lb>And I ſuppoſe it will not be imagin'd that <lb></lb>in this caſe the Bladder was broken by its <lb></lb>own Fibres, rather then by the Impri<lb></lb>ſon'd Air. </s></p><p type="margin"> <s><margin.target id="marg7"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 5.</s></p><p type="main"> <s>And of this Experiment theſe two <emph type="italics"></emph>Phæ<lb></lb>nomena<emph.end type="italics"></emph.end> may be taken notice of: The one, <lb></lb>that the Bladder at its breaking gave a <lb></lb>great report, almoſt like a Craker: And <lb></lb>the other, That the Air contain'd in the <lb></lb>Bladder, had the power to break it with <lb></lb>the mention'd Impetuoſity, long before <lb></lb>the ambient Air was, all or near all, drawn <lb></lb>out of the Receiver. </s></p><p type="main"> <s>But, to verifie what we ſay in another <lb></lb>Diſcourſe, where we ſhow, That even <pb xlink:href="013/01/091.jpg" pagenum="51"></pb>true Experiments may, by reaſon of <lb></lb>the eaſie miſtake of ſome unheeded <lb></lb>Circumſtance, be unſucceſsfully try'd; <lb></lb>we will Advertiſe, on this occaſion, <lb></lb>that we did oftentimes in vain try the <lb></lb>breaking of Bladders, after the manner <lb></lb>above-mention'd: Of which the cauſe <lb></lb>appear'd to be this, That the Bladders we <lb></lb>could not break, having been brought us <lb></lb>ready blown from thoſe that ſold them, <lb></lb>were grown dry before they came to our <lb></lb>hands: whence it came to paſs, that, if <lb></lb>we afterwards ty'd them very hard, they <lb></lb>were apt to fret and ſo become unſervice<lb></lb>able; and if we ty'd them but moderate<lb></lb>ly hard, their ſtiffneſs kept them from be<lb></lb>ing cloſ'd ſo exactly, but that when the <lb></lb>included Air had in the exhauſted Recei<lb></lb>ver diſtended them as much as eaſily it <lb></lb>could, it would in part get out between <lb></lb>the little wrinkles of the Sphincter of the <lb></lb>Neck: Whence alſo it uſually happen'd, <lb></lb>that, upon the letting in the Air from <lb></lb>without, the Bladders appear'd more flac<lb></lb>cid and empty then before they were put <lb></lb>in; whereas when the Bladders were <lb></lb>brought us moiſt from the Butchers, we <lb></lb>could, without injuring them, tye their <lb></lb>necks ſo cloſe, that none of the Air once <pb xlink:href="013/01/092.jpg" pagenum="52"></pb>blown in, could get out of them, but by <lb></lb>violently breaking them. </s></p><p type="main"> <s>It will not be amiſs on this occaſion to <lb></lb>point at ſomething which may deſerve a <lb></lb>more deliberate Speculation then we can <lb></lb>now afford it; namely that the Elaſtical <lb></lb>Power of the ſame Quantity of Air may <lb></lb>be as well Encreaſ'd by the Agitation of <lb></lb>the Aërial Particles (whether onely mo<lb></lb>ving them more ſwiftly and ſcattering <lb></lb>them, or alſo extending or ſtretching <lb></lb>them out, I determine not) within an <lb></lb>every way incloſing and yet yielding Bo<lb></lb>dy; as Diſplay'd by the withdrawing of <lb></lb>the Air that preſſ'd it without. </s> <s>For we <lb></lb>found that a Bladder, but moderately <lb></lb>fill'd with Air and ſtrongly ty'd, being <lb></lb>a while held near the Fire, not onely grew <lb></lb>exceeding turgid and hard, but after<lb></lb>wards, being approach'd nearer to the <lb></lb>Fire, ſuddenly broke with ſo loud and ve<lb></lb>hement a noiſe, as ſtony'd thoſe that were <lb></lb>by, and made us, for a while after, almoſt <lb></lb>deaf. </s></p><p type="main"> <s>HAving thus ſeen that the Air has an <lb></lb><arrow.to.target n="marg8"></arrow.to.target><lb></lb>Elaſtical Power, we were next deſi<lb></lb>rous to know in ſome meaſure how far a <pb xlink:href="013/01/093.jpg" pagenum="53"></pb>parcel of Air might by this its own Spring <lb></lb>be dilated. </s> <s>And though we were not pro<lb></lb>vided of Inſtruments fit to meaſure the <lb></lb>dilatation of the Air any thing accurately, <lb></lb>yet becauſe an imperfect meaſure of it was <lb></lb>more deſireable then none at all, we de<lb></lb>viſ'd the following Method as very eaſily <lb></lb>practicable. </s></p><p type="margin"> <s><margin.target id="marg8"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 6.</s></p><p type="main"> <s>We took a limber Lambs Bladder <lb></lb>which was thorowly wetted in fair Water, <lb></lb>that the ſides of it being ſqueez'd roge<lb></lb>ther, there might be no Air left in its <lb></lb>folds: (as indeed we could not afterwards <lb></lb>upon tryal diſcern any) The neck of this <lb></lb>Bladder was ſtrongly tyed about that of <lb></lb>a ſmall Glaſs, (capable of holding five <lb></lb>full drachmes of Water) the Bladder be<lb></lb>ing firſt ſo compreſſ'd, that all the inclu<lb></lb>ded Air was onely in the Glaſs, without <lb></lb>being preſſ'd there; then the Pump be<lb></lb>ing ſet awork after a few exſuctions, the <lb></lb>Air in the little Viol began to dilate it <lb></lb>ſelf and produce a ſmall Tumor in the <lb></lb>Neck of the Bladder; and as the ambi<lb></lb>ent Air was more and more drawn away, <lb></lb>ſo the included Air penetrated further and <lb></lb>further into the Bladder, and by degrees <lb></lb>lifted up the ſides and diſplay'd its folds, <lb></lb>till at length it ſeem'd to have blown it <pb xlink:href="013/01/094.jpg" pagenum="54"></pb>up to its full extent: whereupon the ex<lb></lb>ternal Air, being permitted to flow back <lb></lb>into the Reciver, repulſ'd the Air that <lb></lb>had fill'd the Bladder into its former nar<lb></lb>row receptacle, and brought the Bladder <lb></lb>to be again flaccid and wrinkled as before: <lb></lb>Then taking out the Bladder, but with<lb></lb>out ſevering it from the Glaſs, we did by <lb></lb>a hole made at the top of the Bladder fill <lb></lb>the Veſſel they both made up with Wa<lb></lb>ter, whoſe weight was five Ounces five <lb></lb>Drachmes and an half: Five Drachmes <lb></lb>whereof were above-mention'd to be the <lb></lb>contents of the Bottle. </s> <s>So that in this Ex<lb></lb>periment, when the Air had moſt extend<lb></lb>ed the Bladder, it poſſeſſ'd in all above <lb></lb>nine times as much room as it did when it <lb></lb>was put into the Receiver. </s> <s>And it would <lb></lb>probably have much inlarg'd its bounds, <lb></lb>but that the Bladder by its weight and the <lb></lb>ſticking together of its ſides did ſome<lb></lb>what reſiſt its expanſion: And which was <lb></lb>more conſiderable, the Bladder appear'd <lb></lb>tumid enough, whilſt yet a pretty deal of <lb></lb>Air was left in the Receiver, whoſe ex<lb></lb>ſuction would, according to our former <lb></lb>Obſervation, probably have given way <lb></lb>to a further expanſion of the Air, eſpeci-<pb xlink:href="013/01/095.jpg" pagenum="55"></pb>ally ſuppoſing the dilatation not to be re<lb></lb>ſtrain'd by the Bladder. </s></p><p type="main"> <s>SInce we wrote the other day the former <lb></lb>Experiment, we have met with ſome <lb></lb>Glaſſes not very unfit for our purpoſe; <lb></lb>by means of which we are now able, with <lb></lb>a little more trouble, to meaſure the ex<lb></lb>panſion of the Air a great deal more ac<lb></lb>curately then we could by the help of the <lb></lb>above-mention'd Bladder, which was <lb></lb>much to narrow to allow the Air its ut<lb></lb>moſt diſtention. </s></p><p type="main"> <s>We took then firſt a Cylindrical Pipe <lb></lb>of Glaſs, whoſe bore was about a quarter <lb></lb>of an Inch in Diameter: this Pipe was ſo <lb></lb>bent and doubled, that, notwithſtanding <lb></lb>its being about two foot in length, it <lb></lb>might have been ſhut up into a ſmall Re<lb></lb>ceiver, not a Foot high: But by miſ<lb></lb>fortune it crack'd in the cooling, whereby <lb></lb>we were reduced to make uſe of one part <lb></lb>which was ſtraight and intire, but exceed<lb></lb>ed not ſix or ſeven Inches. </s> <s>This little <lb></lb>Tube was open at one end; and at the <lb></lb>other, where it was Hermetically ſeal'd, <lb></lb>had a ſmall Glaſs bubble to receive the <lb></lb>Air whoſe dilatation was to be meaſur'd. </s></p><pb xlink:href="013/01/096.jpg" pagenum="56"></pb><p type="main"> <s>Along the ſide of this Tube was paſt<lb></lb>ed a ſtraight narrow piece of Parchment, <lb></lb>divided into twenty ſix equal parts, mark<lb></lb>ed with black Lines and Figures, that by <lb></lb>them might be meaſur'd both the inclu<lb></lb>ded Air and its dilatation. </s> <s>Afterwards <lb></lb>we fill'd the Tube with Water almoſt to <lb></lb>the top, and ſtopping the open end with <lb></lb>a Finger, and inverting the Tube, the <lb></lb>Air was permitted to aſcend to the above<lb></lb>mention'd Glaſs bubble. </s> <s>And by rea<lb></lb>ſon this aſcent was very ſlow, it gave us <lb></lb>the opportunity to mark how much more <lb></lb>or leſs then one of the twenty ſix diviſi<lb></lb>ons this Air took up. </s> <s>By this means, af<lb></lb>ter a tryal or two, we were inabled to con<lb></lb>vey to the top of the Glaſs a bubble of <lb></lb>Air equal enough, as to ſight, to one <lb></lb>of thoſe Diviſions: Then the open end <lb></lb>of the Tube being put into a ſmall Viol, <lb></lb>whoſe bottom was cover'd with Water <lb></lb>about half an Inch high; we included <lb></lb>both Glaſſes into a ſmall and ſlender Re<lb></lb>ceiver, and cauſed the Pump to be ſet a<lb></lb>work. </s> <s>The event was, That at the firſt <lb></lb>exſuction of the Air there appear'd not <lb></lb>any expanſion of the bubble, comparable <lb></lb>to what appear'd at the ſecond, and that <lb></lb>upon a very few exſuctions the bubble <pb xlink:href="013/01/097.jpg" pagenum="57"></pb>reaching as low as the ſurface of the ſub<lb></lb>jacent Water, gave us cauſe to think <lb></lb>that if our Pipe had not been broken it <lb></lb>would have expanded it ſelf much fur<lb></lb>ther: Wherefore we took out the little <lb></lb>Tube, and found that beſides the twenty <lb></lb>ſix diviſions formerly mention'd, the <lb></lb>Glaſs bubble and ſome part of the Pipe <lb></lb>to which the divided Parchment did not <lb></lb>reach, amounted to ſix diviſions more. <lb></lb></s> <s>Whereby it appears that the air had taken <lb></lb>up one and thirty times as much room as <lb></lb>before, and yet ſeem'd capable of a much <lb></lb>greater expanſion, if the Glaſs would <lb></lb>have permitted it. </s> <s>Wherefore, after the <lb></lb>former manner, we let in another bubble, <lb></lb>that by our gueſs was but half as big as <lb></lb>the former, and found, that upon the ex<lb></lb>ſuction of the Air from the Receiver, this <lb></lb>little bubble did not onely fill up the <lb></lb>whole Tube, but (in part) break through <lb></lb>the ſubjacent Water in the Viol, and <lb></lb>thereby manifeſt it ſelf to have poſſeſſed <lb></lb>ſixty and odde times its former room. </s></p><p type="main"> <s>Theſe two Experiments are mention'd <lb></lb>to make way for the more eaſie belief of <lb></lb>that which is now to follow. </s> <s>Finding <lb></lb>then that our Tube was too ſhort to ſerve <lb></lb>our turn, we took a ſlender Quill of Glaſs <pb xlink:href="013/01/098.jpg" pagenum="58"></pb>which happen'd to be at hand, though it <lb></lb>were not ſo fit for our purpoſe as we <lb></lb>could have wiſhed, in regard it was three <lb></lb>or four times as big at one end as the o<lb></lb>ther. </s> <s>This Pipe which was thirty Inches <lb></lb>long, being Hermetically ſeal'd at the <lb></lb>ſlender end, was almoſt filled with Wa<lb></lb>ter; and after the above-related manner <lb></lb>a bubble was convey'd to the top of it, <lb></lb>and the open extream was put into a Viol <lb></lb>that had a little fair Water at the bottom: <lb></lb>Then the Cover, by means of a ſmall hole <lb></lb>purpoſely made in it for the Glaſs Pipe to <lb></lb>ſtand out at, was cemented on to the Re<lb></lb>ceiver, and the Pump being ſet awork, <lb></lb>after ſome exſuctions, not onely the Air <lb></lb>manifeſtly appear'd extended below the <lb></lb>ſurface of the ſubjacent Water; but one <lb></lb>of the By-ſtanders affirms, that he ſaw <lb></lb>ſome bubbles come out at the bottom of <lb></lb>the Pipe and break through the Water <lb></lb>This done, we left off Pumping, and ob<lb></lb>ſerv'd how at the unperceiv'd leaks of the <lb></lb>Receiver the Air got in ſo faſt, thatit <lb></lb>very quickly impell'd up the Water to <lb></lb>the top of the Tube, excepting a little <lb></lb>ſpace whereinto that bubble was repulſ'd, <lb></lb>which had ſo lately poſſeſſ'd the whole <lb></lb>Tube; this Air at the ſlender end ap-<pb xlink:href="013/01/099.jpg" pagenum="59"></pb>pear'd to be a Cylinder of 5/6 parts of an <lb></lb>Inch in length; but when the Pipe was <lb></lb>taken out and turn'd upſide down, it ap<lb></lb>pear'd at the other end inferior in bulk to a <lb></lb>Pea. </s></p><p type="main"> <s>Theſe things being thus done we took <lb></lb>(to make the Experiment the more ex<lb></lb>actly) a ſmall pair of Scales, ſuch as Gold<lb></lb>Smiths uſe to weigh Gold Coyn in; and <lb></lb>weighing the Tube and Water in it, we <lb></lb>found them to amount to one Ounce thir<lb></lb>ty Grains and an half: Then we pour'd in <lb></lb>as much Water as ſerv'd to fill up the <lb></lb>Tube, wherein before we had left as much <lb></lb>ſpace unfill'd up as was poſſeſſ'd by the <lb></lb>bubble; and weighing again the Pipe and <lb></lb>Water, we found the weight increaſ'd <lb></lb>onely by one Grain. </s> <s>Laſtly, pouring out <lb></lb>the Water, and carefully freeing the Pipe <lb></lb>from it (which yet we could not perfectly <lb></lb>doe) we weighed the Glaſs alone, and <lb></lb>found it to want two Drachmes and thirty <lb></lb>two Grains of its former weight: So <lb></lb>that the bubble of Air taking up the room <lb></lb>but of one Grain in weight of Water, it <lb></lb>appear'd that the Air by its own <foreign lang="grc">ἐλιτὴρ</foreign><lb></lb>was ſo rarified, as to take up one hundred <lb></lb>fifty two times as much room as it did be<lb></lb>fore: though it were then compreſſ'd by <pb xlink:href="013/01/100.jpg" pagenum="60"></pb>nothing but the ordinary preſſure of the <lb></lb>contiguous Air. </s> <s>I know not whether it <lb></lb>be requiſite to take notice, that this Ex<lb></lb>periment was made indeed in a moiſt <lb></lb>Night, but in a Room, in whoſe Chim<lb></lb>ney there was burning a good Fire, which <lb></lb>did perhaps ſomewhat rarifie the Air of <lb></lb>which the bubble conſiſted. </s></p><p type="main"> <s>It has ſeem'd almoſt incredible which is <lb></lb>related by the Induſtrious <emph type="italics"></emph>Merſennus,<emph.end type="italics"></emph.end> That <lb></lb>the Air by the violence of heat, though <lb></lb>as great as our Veſſels can ſupport with<lb></lb>out fuſion, can be ſo dilated as to take up <lb></lb>ſeventy times as much room as before: <lb></lb>Wherefore becauſe we were willing to <lb></lb>have a confirmation of ſo ſtrange a <emph type="italics"></emph>Phæno<lb></lb>menon;<emph.end type="italics"></emph.end> we once more convey'd into the <lb></lb>Tube a bubble of the bigneſs of the for<lb></lb>mer, and proſecuting the Experiment as <lb></lb>before with the ſame Water, we obſerved <lb></lb>that the Air did manifeſtly ſtretch it ſelf <lb></lb>ſo far, as to appear ſeveral times a good <lb></lb>way below the ſurface of the Water in the <lb></lb>Viol, and that too with a ſurface very <lb></lb>convex toward the bottom of the Pipe. <lb></lb></s> <s>Nay, the Pump being ply'd a little lon<lb></lb>ger, the Air did manifeſtly reach to that <lb></lb>place where the bottom of the Tube <lb></lb>lean'd upon the bottom of the Viol, and <pb xlink:href="013/01/101.jpg" pagenum="61"></pb>ſeem'd to knock upon it and rebound <lb></lb>from it: Which Circumſtances we adde, <lb></lb>partly that the <emph type="italics"></emph>Phænomenon<emph.end type="italics"></emph.end> we have been <lb></lb>relating may not be imputed to the <lb></lb>bare ſubſiding of the Water that fill'd <lb></lb>the Tube, upon the taking off the preſ<lb></lb>ſure of the ambient Air. </s> <s>And partly al<lb></lb>ſo that it may appear that if our Expe<lb></lb>riments have not been as accurately made <lb></lb>as with fitter Inſtruments might perhaps <lb></lb>be poſſible; yet the expanſion of the <lb></lb>Air is likely to be rather greater then <lb></lb>leſſer then we have made it: Since the <lb></lb>Air was able to preſs away the Water at <lb></lb>the bottom of the Pipe, though that were <lb></lb>about two Inches below the ſurface of the <lb></lb>Water that was then in the Viol, and <lb></lb>would have been at leaſt as high in the <lb></lb>Pipe, if the Water had onely ſubſided and <lb></lb>not been depreſſed: So that it ſeems not <lb></lb>unlikely that if the Experiment could be <lb></lb>ſo made, as that the expanſion of the Air <lb></lb>might not be reſiſted by the Neighboring <lb></lb>Bodies, it would yet inlarge its bounds, <lb></lb>and perhaps ſtretch it ſelf to two hundred <lb></lb>times its former bulk, if not more. </s> <s>How<lb></lb>ever, what we have now try'd will, I hope, <lb></lb>ſuffice to hinder divers of the <emph type="italics"></emph>Phænomena<emph.end type="italics"></emph.end><lb></lb>of our Engine from being diſtruſted: <pb xlink:href="013/01/102.jpg" pagenum="62"></pb>Since in that part of the Atmoſphere we <lb></lb>live in, that which we call the free Air (and <lb></lb>preſume to be ſo uncompreſſ'd) is crouded <lb></lb>into ſo very ſmall a part of that ſpace, <lb></lb>which if it were not hindred it would poſ<lb></lb>ſeſs. </s> <s>We would gladly have tryed alſo <lb></lb>whether the Air at its greateſt expanſion <lb></lb>could be further rarified by heat; but do <lb></lb>what we could, our Receiver leak'd too <lb></lb>faſt to let us give our ſelves any ſatisfacti<lb></lb>on in that particular. </s></p><p type="main"> <s>TO diſcover likewiſe by the means of <lb></lb><arrow.to.target n="marg9"></arrow.to.target><lb></lb>that preſſure of the Air, both the <lb></lb>ſtrength of Glaſs, and how much inte<lb></lb>reſt the Figure of a Body may have in its <lb></lb>greater or leſſer Reſiſtance to the preſſure <lb></lb>of other Bodys, we made theſe further <lb></lb>tryals. </s></p><p type="margin"> <s><margin.target id="marg9"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 7.</s></p><p type="main"> <s>We cauſ'd to be blown with a Lamp a <lb></lb>round Glaſs bubble, capable of contain<lb></lb>ing, by gueſs, about five Ounces of Wa<lb></lb>ter, with a ſlender neck about the bigneſs <lb></lb>of a Swans Quill, and it was purpoſely <lb></lb>blown very thin, as Viols made with <lb></lb>Lamps are wont to be, that the thinneſs <lb></lb>of the matter might keep the roundneſs <lb></lb>of the Figure from making the Veſſel too <pb xlink:href="013/01/103.jpg" pagenum="63"></pb>ſtrong. </s> <s>Then having moderately empty<lb></lb>ed the Receiver, and taken it out of the <lb></lb>Pump, we ſpeedily applyed to the Ori<lb></lb>fice of the bottom of it the Neck of the <lb></lb>newly mention'd Glaſs, carefully ſtopping <lb></lb>the Crannys with melted Plaiſter, that no <lb></lb>Air might get in at them: And after <lb></lb>turning the Key of the Stop-cock, we <lb></lb>made a free paſſage for the Air to paſs out <lb></lb>of the bubble into the Receiver: which it <lb></lb>did with great celerity, leaving the bub<lb></lb>ble as empty as the Receiver it ſelf; as ap<lb></lb>pear'd to us by ſome Circumſtances not <lb></lb>now to be inſiſted on. </s> <s>Notwithſtanding <lb></lb>all which, the Veſſel, continuing as intire <lb></lb>as before, gave us cauſe to wonder that <lb></lb>the bare Roundneſs of the Figure ſhould <lb></lb>inable a Glaſs, almoſt as thin as Paper, to <lb></lb>reſiſt ſo great a preſſure as that of the <lb></lb>whole incumbent Atmoſphere. </s> <s>And ha<lb></lb>ving reiterated the Experiment, we found <lb></lb>again that the preſſure of the ambient <lb></lb>Body, thruſting all the parts inwards, <lb></lb>made them, by reaſon of their arched Fi<lb></lb>gure, ſo ſupport one another, that the <lb></lb>Glaſs remain'd as whole as at firſt. </s></p><p type="main"> <s>Now that the Figure of the Glaſs is <lb></lb>of great moment in this matter, may be <lb></lb>evinced by this other Experiment. </s></p><pb xlink:href="013/01/104.jpg" pagenum="64"></pb><p type="main"> <s>WE took a Glaſs Helmet or Alem<lb></lb><arrow.to.target n="marg10"></arrow.to.target><lb></lb>bick (delineated by the ſeventh <lb></lb>Figure) ſuch as Chymiſts uſe in Diſtilla<lb></lb>tions, and containing by conjecture be<lb></lb>tween two and three Pints: The <emph type="italics"></emph>Roſtrum<emph.end type="italics"></emph.end><lb></lb>or Noſe of it mark'd with <emph type="italics"></emph>(c)<emph.end type="italics"></emph.end> was Herme<lb></lb>tically cloſed; and at the top of it was a <lb></lb>hole, into which was fitted and cemented <lb></lb>one of the Shanks of a middle-ſiz'd Stop<lb></lb>cock; ſo that the Glaſs being turn'd up<lb></lb>ſide-down, the wide Orifice (which in <lb></lb>common Glaſs-Helmets is the onely one) <lb></lb>was upwards; and to that wide Orifice <lb></lb>was fitted a caſt-Cover of Lead, which <lb></lb>was carefully cemented on to the Glaſs: <lb></lb>Then the other Shank of the Stop-cock <lb></lb>being with Cement likewiſe faſten'd into <lb></lb>the upper part of the Pump, the exſucti<lb></lb>on of the Air was endeavoured. </s> <s>But it <lb></lb>was not long before, the remaining Air <lb></lb>being made much too weak to ballance <lb></lb>the preſſure of the ambient Air, the Glaſs <lb></lb>was not without a great noiſe crack'd al<lb></lb>moſt half round, along that part of it <lb></lb>where it began to bend inwards: As if <lb></lb>in the Figure the crack had been made ac<lb></lb>cording to the Line <emph type="italics"></emph>(ab);<emph.end type="italics"></emph.end> and upon an <pb xlink:href="013/01/105.jpg" pagenum="65"></pb>endeavour to pump out more of the Air, <lb></lb>the crack once began, appear'd to run on <lb></lb>further; though the Glaſs where it was <lb></lb>broken ſeem'd to be by conjecture above <lb></lb>ten, ſome thought above twenty times as <lb></lb>thick as the bubble mention'd in the fore<lb></lb>going Experiment. </s></p><p type="margin"> <s><margin.target id="marg10"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 8.</s></p><p type="main"> <s>This will perhaps make it ſeem ſtrange, <lb></lb>that having taken another Glaſs bubble <lb></lb>blown at the ſame time, and like for <lb></lb>ought we diſcern'd for ſize, thickneſs <lb></lb>and Figure to that thin one formerly <lb></lb>mention'd; and having ſeal'd it up Her<lb></lb>metically, and ſuſpended it in the Recei<lb></lb>ver, the exſuction of the ambient Air did <lb></lb>not enable the impriſoned Air to break, or <lb></lb>in the leaſt to crack the bubble; though <lb></lb>the Experiment were laboriouſly try'd, <lb></lb>and that ſeveral times with bubbles of o<lb></lb>ther ſizes: But that perhaps the heat of <lb></lb>the Candle or Lamp wherewith ſuch <lb></lb>Glaſſes are Hermetically ſeal'd, (not to <lb></lb>mention the warmth of his hands that <lb></lb>ſeal'd it) might ſo rarifie the contained <lb></lb>Air, as much to weaken its Spring, may <lb></lb>ſeem probable by the following Expe<lb></lb>riments. </s></p><pb xlink:href="013/01/106.jpg" pagenum="66"></pb><p type="main"> <s>WE took a Glaſs Viol able to hold <lb></lb><arrow.to.target n="marg11"></arrow.to.target><lb></lb>three or four Ounces of Water, <lb></lb>and of the thickneſs uſual in Glaſſes of <lb></lb>that ſize; into the Neck of this was put <lb></lb>a moderately ſlender Pipe of Glaſs, which <lb></lb>was carefully faſten'd with a mixture of e<lb></lb>qual parts of Pitch and Roſin to the Neck <lb></lb>of the Viol, and which reach'd almoſt to <lb></lb>the bottom of it, as the ſixth Figure de<lb></lb>clares. </s></p><p type="margin"> <s><margin.target id="marg11"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 9.</s></p><p type="main"> <s>This Viol being upon a particular de<lb></lb>ſign fill'd with Water, till that came up in <lb></lb>it a pretty deal higher then the lower end <lb></lb>of the Pipe, was put into one of our ſmall <lb></lb>Receivers, (containing between a Pint <lb></lb>and a Quart) in ſuch manner as that the <lb></lb>Glaſs Pipe, paſſing through a hole made <lb></lb>purpoſely for it in the Leaden-Cover of <lb></lb>the Receiver, was for the moſt part of it <lb></lb>without the Veſſel, which being exactly <lb></lb>cloſed, the Pump was ſet awork: But at <lb></lb>the very firſt exſuction, and before the <lb></lb>Sucker was drawn to the bottom of the <lb></lb>Cylinder, there flew out of the Viol a <lb></lb>piece of Glaſs half as broad as the Palm <lb></lb>of a Mans Hand, and it was thrown out <lb></lb>with ſuch violence, that hitting againſt <pb xlink:href="013/01/107.jpg" pagenum="67"></pb>the Neighboring ſide of the Receiver, it <lb></lb>not onely dafh'd it ſelf to pieces, but <lb></lb>crack'd the very Receiver in many places, <lb></lb>with a great noiſe that much ſurpriſed all <lb></lb>that were in the Room. </s> <s>But it ſeem'd <lb></lb>that in ſo little a Receiver, the Air about <lb></lb>the Viol being ſuddenly drawn out, the <lb></lb>Air Impriſon'd in the Veſſel, having on <lb></lb>it the whole preſſure of the Atmoſphere <lb></lb>(to which by the Pipe open at both ends, <lb></lb>It and the Water were expoſ'd) and not <lb></lb>having on the other ſide the wonted preſ<lb></lb>ſure of the Ambient Air to ballance that <lb></lb>other preſſure, the reſiſtance of the Glaſs <lb></lb>was finally ſurmounted, and the Viol once <lb></lb>beginning to break where it was weakeſt, <lb></lb>the external Air might ruſh in with vio<lb></lb>lence enough to throw the crack'd parcel <lb></lb>ſo forcibly againſt the Neighboring ſide <lb></lb>of the Receiver, as to break that too. </s></p><p type="main"> <s>And this may be preſumed ſufficient to <lb></lb>verifie what we delivered in that part of <lb></lb>our Appendix to the firſt Experiment, <lb></lb>where we mention'd the almoſt equal <lb></lb>preſſure of the Air on either ſide of a <lb></lb>thin Glaſs Veſſel, as the cauſe of its not <lb></lb>being broken by the forcible Spring of <lb></lb>the contain'd Air. </s> <s>But yet that it be not <lb></lb>ſuſpected that chance had an intereſt in ſo <pb xlink:href="013/01/108.jpg" pagenum="68"></pb>odde an Experiment as we have been Re<lb></lb>lating, we will adde that for farther ſatiſ<lb></lb>faction we reiterated it in a round Glaſſe <lb></lb>containing by gueſſe about ſix ounces <lb></lb>of water: this violl we put into ſuch a <lb></lb>ſmall Receiver as was lately mention'd, <lb></lb>in ſuch manner as that the bottome of <lb></lb>it reſted upon the lower part of the Pneu<lb></lb>maticall Glaſſe, and the Neck came out <lb></lb>through the Leaden-Cover of the ſame <lb></lb>at a hole made purpoſely for it. </s> <s>But be<lb></lb>ing made circumſpect by the foregoing <lb></lb>miſchance, we had put the violl into a <lb></lb>Bladder, before we put it into the Re<lb></lb>ceiver to hinder this laſt named Glaſſe <lb></lb>from being endanger'd by the breaking <lb></lb>of the other. </s> <s>Then the Pneumaticall <lb></lb>veſſell being clos'd ſo that no way was <lb></lb>left for the outward Air to get into it, <lb></lb>but by breaking through the Viol, into <lb></lb>whoſe cavity it had free acceſſe by the <lb></lb>mouth of it, (which was purpoſely left <lb></lb>open,) the Sucker being nimbly drawn <lb></lb>down, the external Air immediatly preſſ'd <lb></lb>forcibly as well upon the Leaden-Co<lb></lb>ver as the Violl; and the Cover hap<lb></lb>pening to be in one place a little narrow<lb></lb>er then the edge of the Pneumatical Glaſs, <lb></lb>was depreſſ'd, and thruſt into it ſo vio-<pb xlink:href="013/01/109.jpg" pagenum="69"></pb>lently by the incumbent Air, that get<lb></lb>ting a little within the tapering Lip of the <lb></lb>Glaſs, it did like a kinde of Wedge, thruſt <lb></lb>out that ſide where it was depreſſ'd, ſo as, <lb></lb>though the Receiver was new, to ſplit it. <lb></lb></s> <s>This accident being thus mention'd upon <lb></lb>the by to confirm what we formerly ſaid <lb></lb>touching the fitneſs or unfitneſs of Glaſſes <lb></lb>of ſome Figures to reſiſt the preſſure of <lb></lb>the Atmoſphere; We will proceed to <lb></lb>relate the remaining part of the Experi<lb></lb>ment, namely, That having fitted on a <lb></lb>wider Cover to the ſame Receiver, and <lb></lb>cloſed both that and the crack with Ce<lb></lb>ment, we proſecuted the Experiment in <lb></lb>the manner above related, with this ſuc<lb></lb>ceſs: That upon the quick depreſſing of <lb></lb>the Sucker, the external Air burſt the <lb></lb>Body of the Viol in above a hundred pie<lb></lb>ces, many of them exceeding ſmall, and <lb></lb>that with ſuch violence that we found a <lb></lb>wide rent, beſides many holes, made in <lb></lb>the Bladder it ſelf. </s></p><p type="main"> <s>And to evince that theſe <emph type="italics"></emph>Phænomena<emph.end type="italics"></emph.end><lb></lb>were the effects of a limited and even <lb></lb>moderate force, and not of ſuch an ab<lb></lb>horrency of a <emph type="italics"></emph>Vacuum<emph.end type="italics"></emph.end> as that to avoid it, <lb></lb>many have been pleaſed to think that Na<lb></lb>ture muſt, upon occaſion, exerciſe an al-<pb xlink:href="013/01/110.jpg" pagenum="70"></pb>moſt boundleſs power; we afterwards pur<lb></lb>poſely try'd this Experiment with ſeveral <lb></lb>Glaſſes ſomewhat thicker then thoſe Vi<lb></lb>ols, and found the event to verifie our con<lb></lb>jecture, that it would not ſucceed: for <lb></lb>the Glaſſes were taken out as intire as they <lb></lb>were put in. </s></p><p type="main"> <s>And here, My Lord, I hold it not un<lb></lb>fit, upon occaſion of the mention that <lb></lb>has been made of our having employ'd <lb></lb>ſmall Receivers, and one of them, not<lb></lb>withſtanding its being crack'd, to annex <lb></lb>theſe two Advertiſements. </s></p><p type="main"> <s>Firſt then, beſides the great Pneuma<lb></lb>tical Glaſs ſo often mention'd, and the <lb></lb>proportionate Stop-cock, we thought fit <lb></lb>to provide our ſelves of ſome ſmall Recei<lb></lb>vers blown of Cryſtalline Glaſs, of ſeve<lb></lb>rall Shapes, and furniſhed with ſmaller <lb></lb>Stop-cocks purpoſely made; and this we <lb></lb>did upon hopes that when we had ſur<lb></lb>mounted the difficulties to be met with in <lb></lb>Cementing the Glaſſes to the Stop<lb></lb>cocks, and the Pneumatical Veſſels to the <lb></lb>Pump ſo exquiſitely as is requiſite for our <lb></lb>purpoſe, we ſhould from the ſmalneſs of <lb></lb>our Receivers receive a four-fold Advan<lb></lb>tage. </s> <s>The firſt, that by reaſon of the <lb></lb>ſlenderneſs of the Veſſels, and their be-<pb xlink:href="013/01/111.jpg" pagenum="71"></pb>ing made of much purer and clearer me<lb></lb>tall, as the Glaſs-men ſpeak, then the <lb></lb>great Receiver, we might have a more <lb></lb>perfect view of every thing happening <lb></lb>within them. </s> <s>The next, that ſuch ſmall <lb></lb>Veſſels might be empty'd with leſs la<lb></lb>bour and in much leſſe time. </s> <s>The third, <lb></lb>that this nimble exſuction of the ambient <lb></lb>Air would make many changes in the <lb></lb>Bodies ſhut up in theſe glaſſes more ſud<lb></lb>den and conſpicuous then otherwiſe they <lb></lb>would prove. </s> <s>And the laſt, that we ſhould <lb></lb>be able to draw and keep out the Air much <lb></lb>more perfectly from ſuch ſmall Veſſels <lb></lb>then from our large Receiver. </s> <s>But though <lb></lb>we were not much diſ-appointed in the <lb></lb>expectation of the three firſt advantages, <lb></lb>yet we were in our hopes of the fourth. <lb></lb></s> <s>For beſides the great difficulty we found <lb></lb>in fitting together the Glaſſes, the Stop<lb></lb>cocks and the Covers; beſides this I ſay, <lb></lb>we found our ſelves ſeldom able to draw, <lb></lb>and keep out the Air ſo far as to make the <lb></lb>remaining Air in theſe Receivers weaker <lb></lb>then the remaining Air in our great Recei<lb></lb>ver. </s> <s>For though ſometimes the Leaks <lb></lb>of ſome of theſe little Receivers may be <lb></lb>much either fewer or ſmaller then thoſe <lb></lb>of the larger Veſſel; yet a little Air get-<pb xlink:href="013/01/112.jpg" pagenum="72"></pb>ting into one of theſe, wherein it had but <lb></lb>little room to expand and diſplay it ſelf, <lb></lb>might preſs as much upon all parts of the <lb></lb>internal ſurface of the Veſſel, and upon <lb></lb>the included Bodies, as a greater quan<lb></lb>tity of Air in a Veſſel in whoſe capacity <lb></lb>it might finde more room to expand it <lb></lb>ſelf. </s></p><p type="main"> <s>The other thing that we were to ad<lb></lb>vertiſe, is, That 'tis not every ſmall crack <lb></lb>that can make ſuch a Receiver as is of a <lb></lb>roundiſh Figure altogether uſeleſs to our <lb></lb>Experiment, in regard that upon the ex<lb></lb>ſuction of the internal Air, the ambient <lb></lb>Air on all ſides preſſing the Glaſs inwards <lb></lb>or towards the middle, does conſequent<lb></lb>ly thruſt the Lips of the crack cloſer, and <lb></lb>ſo rather cloſe then increaſe it. </s></p><p type="main"> <s>This I mention partly becauſe Recei<lb></lb>vers fit for our turn are more eaſily <lb></lb>crack'd then procur'd, and therefore ought <lb></lb>not to be unneceſſarily thrown away as <lb></lb>unſerviceable: And partly becauſe I think <lb></lb>it becomes one that profeſſes himſelf a <lb></lb>faithful Relator of Experiments, not to <lb></lb>conceal from Your Lordſhip, that after a <lb></lb>few of the foregoing Experiments were <lb></lb>made, there happen'd in the great Recei<lb></lb>ver a crack of about a Span long, begin-<pb xlink:href="013/01/113.jpg" pagenum="73"></pb>ning at the upper Orifice, and occaſion'd, <lb></lb>as it ſeem'd, by the exceſſive heat of too <lb></lb>large an Iron that was employ'd to melt <lb></lb>the Cement about that Orifice. </s> <s>But ha<lb></lb>ving laid upon this crack a broad Plaiſter, <lb></lb>which in one of our Eſſays written ſome <lb></lb>years ſince to your ingenious and hopeful <lb></lb>Couſin <emph type="italics"></emph>Fones,<emph.end type="italics"></emph.end> we extoll for the mending <lb></lb>of crack'd Receivers, and other Chymi<lb></lb>cal Glaſſes; and having afterwards thick<lb></lb>ly over-laid this Plaiſter with Diachylon, <lb></lb>we neither could then, nor can yet per<lb></lb>ceive that the Veſſel leaks ſenſibly at that <lb></lb>crack. </s></p><p type="main"> <s>The Plaiſter was made of good quick <lb></lb>Lime finely poudred, and nimbly ground <lb></lb>with a Peſtle in a Morter, with a quantity <lb></lb>(I know not how much preciſely, not ha<lb></lb>ving thoſe Eſſays in this place) of ſcra<lb></lb>pings of Cheeſe and a little fair Water, <lb></lb>no more then is juſt neceſſary to bring the <lb></lb>mixture to a ſomewhat ſoft Paſte, which <lb></lb>when the Ingredients are exquiſitely in<lb></lb>corporated, will have a ſtrong and <lb></lb>ſtincking ſmell: Then it muſt be im<lb></lb>mediately ſpread upon a Linnen Cloath <lb></lb>three or four fingers breadth, and preſently <lb></lb>apply'd, leſt it begin to harden. </s> <s>But if <lb></lb>Your Lordſhip had ſeen how we mended <pb xlink:href="013/01/114.jpg" pagenum="74"></pb>with it Receivers even for the moſt ſub<lb></lb>tle Chymical Spirits, You would ſcarce <lb></lb>wonder at the ſervice it has done in our <lb></lb>Pneumatical Glaſs. </s></p><p type="main"> <s>WE took a Tallow-Candle of ſuch <lb></lb><arrow.to.target n="marg12"></arrow.to.target><lb></lb>a ſize that eight of them make <lb></lb>about a pound, and having in a very com<lb></lb>modious Candleſtick let it down into the <lb></lb>Receiver, and ſo ſuſpended it that the <lb></lb>Flame burnt almoſt in the middle of the <lb></lb>Veſſel, we did in ſome two minutes ex<lb></lb>actly cloſe it up: and, upon Pumping ve<lb></lb>ry nimbly, we found that within little <lb></lb>more then half a minute after the Flame <lb></lb>went out, though the Snuff had been <lb></lb>purpoſely left of that length we judged <lb></lb>the moſt convenient for the laſting of <lb></lb>the Flame. </s></p><p type="margin"> <s><margin.target id="marg12"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 10.</s></p><p type="main"> <s>But the ſecond time having put in the <lb></lb>ſame Candle into the Receiver, (after it <lb></lb>had by the blaſts of a pair of Bellows <lb></lb>been freed from Fumes) the Flame laſted <lb></lb>about two minutes from the time the <lb></lb>Pumper began to draw out the Air; up<lb></lb>on the firſt exſuction whereof, the Flame <lb></lb>ſeem'd to contract it ſelf in all its Dimen<lb></lb>ſions. </s> <s>And theſe things were further ob-<pb xlink:href="013/01/115.jpg" pagenum="75"></pb>ſervable, that after the two or three firſt <lb></lb>exſuctions of the Air, the Flame (except <lb></lb>at the very top) appear'd exceeding blew, <lb></lb>and that the Flame ſtill receded more and <lb></lb>more from the Tallow, till at length it <lb></lb>appear'd to poſſeſs onely the very top of <lb></lb>the Week, and there it went out. </s></p><p type="main"> <s>The ſame Candle being lighted again <lb></lb>was ſhut into the Receiver, to try how it <lb></lb>would laſt there without drawing forth <lb></lb>the Air, and we found that it laſted much <lb></lb>longer then formerly; and before it went <lb></lb>out receded from the Tallow towards the <lb></lb>the top of the Week, but not near ſo <lb></lb>much as in the former Experiment. </s></p><p type="main"> <s>And having an intention to obſerve par<lb></lb>ticularly what the motion of the ſmoak <lb></lb>would be in theſe Experiments: We <lb></lb>took notice that when the Air was not <lb></lb>drawn out, there did upon the extinction <lb></lb>of the Flame a conſiderable part of the <lb></lb>Week remain kindled, which (probably <lb></lb>by reaſon of the Circulation of the Air <lb></lb>in the Veſſel, occaſion'd by the heat) e<lb></lb>mitted a Steam, which aſcended ſwiftly <lb></lb>and directly upwards in a ſlender and unin<lb></lb>terrupted Cylinder of ſmoke, till it came <lb></lb>to the top, whence it manifeſtly recoyl'd <lb></lb>by the ſides to the lower part of the Veſ-<pb xlink:href="013/01/116.jpg" pagenum="76"></pb>ſel. </s> <s>Whereas when the Flame went out <lb></lb>upon the exſuction of the Air one time <lb></lb>(when the Flame retir'd very leaſurely <lb></lb>to the top) we perceived it not to be fol<lb></lb>low'd by any ſmoke at all. </s> <s>And at an <lb></lb>other time the upper part of the Week <lb></lb>remaining kindled after the extinction <lb></lb>of the Flame, the ſlender ſteam of Fumes <lb></lb>that did ariſe aſcended but a very little <lb></lb>way, and then after ſome uncertain mo<lb></lb>tions this and that way, did, for the moſt <lb></lb>part, ſoon fall downwards. </s></p><p type="main"> <s>Being deſirous alſo to try whether <lb></lb>there would be any difference as well in <lb></lb>our Receiver as there is wont to be elſe<lb></lb>where betwixt Candles made of Wax and <lb></lb>thoſe made of Tallow, as to their dura<lb></lb>tion; we took ſlender Tapers of white <lb></lb>Wax, (commonly called Virgins Wax) <lb></lb>that being found to burn with much leſs <lb></lb>ſmoke then common yellow Wax: Six <lb></lb>of theſe of like bigneſs, and each of them <lb></lb>of about the thickneſs of a Swans Quill, <lb></lb>we preſſ'd together into one Candle: And <lb></lb>having lighted all the Weeks, we let in <lb></lb>the above-mention'd Wax into the Re<lb></lb>ceiver, and made what haſte we could to <lb></lb>cloſe it up with Cement. </s> <s>But though in <lb></lb>the mean while we left open the Valve <pb xlink:href="013/01/117.jpg" pagenum="77"></pb>of the Cylinder, the hole of the Stop<lb></lb>cock and that in the Cover of the Re<lb></lb>ceiver, that ſome Air might get in to <lb></lb>cheriſh the Flame and the ſmoke might <lb></lb>have a vent; Yet for ſo great a Flame <lb></lb>the Air ſufficed not ſo much as till the <lb></lb>Cover could be perfectly luted on: So <lb></lb>that before we were quite ready to imploy <lb></lb>the Pump, the Candle was extinguiſhed. <lb></lb></s> <s>Wherefore we took but one of the a<lb></lb>bove mention'd Tapers, and having <lb></lb>lighted it, cloſ'd it up in the Receiver, to <lb></lb>try how long a ſmall Flame with a pro<lb></lb>portionable ſmoke would continue in <lb></lb>ſuch a quantity of Air: But we found <lb></lb>upon two ſeveral tryals, that from the <lb></lb>beginning of pumping, the Flame went <lb></lb>out in about a minute of an hour. </s> <s>It <lb></lb>appear'd indeed to us that the ſwinging <lb></lb>of the Wier to and fro (in the Engine <lb></lb>ſhaken by pumping) haſten'd the vaniſh<lb></lb>ing of the Flame, which ſeem'd by that <lb></lb>motion to be caſt ſometimes on one ſide <lb></lb>of the Week and ſometimes on the o<lb></lb>ther; But though once we purpoſely <lb></lb>refrain'd pumping after a very few ex<lb></lb>ſuctions of the Air, that the Flame might <lb></lb>not be agitated, yet it laſted not much <lb></lb>longer then the newly mention'd time. <pb xlink:href="013/01/118.jpg" pagenum="78"></pb>And laſtly, cloſing up the ſame Taper, <lb></lb>lighted again, to diſcover how long it <lb></lb>would laſt without drawing out of the <lb></lb>Air, we found that it burn'd for a while <lb></lb>vividly enough, but afterwards began to <lb></lb>be leſſen'd more and more in all its Di<lb></lb>menſions. </s> <s>And we obſerv'd that the <lb></lb>Flame did not, as before, retire it ſelf by <lb></lb>little and little towards the top, but to<lb></lb>wards the bottom of the Week (from <lb></lb>which yet it did a little withdraw upwards <lb></lb>juſt before it went out) ſo that the upper <lb></lb>part of the Week appear'd for a pretty <lb></lb>while manifeſtly above the top of the <lb></lb>Flame, which having laſted about five <lb></lb>minutes, was ſucceeded by a directly aſ<lb></lb>cending ſtream of Smoak. </s></p><p type="main"> <s>THere was taken a Wier, which being <lb></lb><arrow.to.target n="marg13"></arrow.to.target><lb></lb>bent almoſt in the form of a Screw, <lb></lb>conſtituted ſuch an Inſtrument to contein <lb></lb>Coals and leave them every way acceſſi<lb></lb>ble to the Air, as the tenth Figure de<lb></lb>clares; the breadth of this Veſſel was no <lb></lb>leſs then that it might with eaſe be con<lb></lb>vey'd into the Receiver: And having filld <lb></lb>it to the height of about five Inches with <lb></lb>throughly kindled Wood-coals, we let <pb xlink:href="013/01/119.jpg" pagenum="79"></pb>it down into the Glaſs; and ſpeedily clo<lb></lb>ſing it, we cauſ'd the Pumper to ply <lb></lb>his work, and obſerv'd that upon the ve<lb></lb>ry firſt exſuction of the Air (though per<lb></lb>haps not becauſe of that onely) the Fire <lb></lb>in the Coals began to grow very dim, and <lb></lb>though the agitation of the Veſſel did <lb></lb>make them ſwing up and down (which in <lb></lb>the free Air would have retarded the ex<lb></lb>tinction of the Fire) yet when we could <lb></lb>no longer diſcern any redneſs at all in any <lb></lb>of them; caſting our eyes upon a Minute<lb></lb>Watch we kept by us on this occaſion, we <lb></lb>found that from the beginning of the <lb></lb>Pumping (which might be about two mi<lb></lb>nutes after the Coals had been put in <lb></lb>glowing) to the total diſ-appearing of <lb></lb>the Fire, there had paſſed but three mi<lb></lb>nutes. </s></p><p type="margin"> <s><margin.target id="marg13"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 11.</s></p><p type="main"> <s>Whereupon, to try the Experiment a <lb></lb>little further, we preſently took out the <lb></lb>Coals, in which it ſeems there had re<lb></lb>mained ſome little parcels of Fire, rather <lb></lb>cover'd then totally quench'd: For in the <lb></lb>open Air the Coals began to be re-kind<lb></lb>led in ſeveral places, wherefore having by <lb></lb>ſwinging them about in the Wier, <lb></lb>throughly lighted them the ſecond time, <lb></lb>welet them down again into the Receiver, <pb xlink:href="013/01/120.jpg" pagenum="80"></pb>and cloſ'd it ſpeedily as before; and then <lb></lb>waiting till the Fire ſeem'd totally ex<lb></lb>tinct without medling with the Pump, we <lb></lb>found that from the time the Veſſel was <lb></lb>cloſ'd till that no Fire at all could be per<lb></lb>ceiv'd there had paſſed about four mi<lb></lb>nutes: Whereby it ſeem'd to appear that <lb></lb>the drawing away of the ambient Air <lb></lb>made the Fire go out ſooner then other<lb></lb>wiſe it would have done; though that part <lb></lb>of the Air that we drew out left the more <lb></lb>room for the ſtifling ſteams of the Coals <lb></lb>to be received into. </s></p><p type="main"> <s>Laſtly, Having taken out the Wier <lb></lb>and put other Coals into it, we did, in the <lb></lb>ſame Room where the Engine ſtood, let it <lb></lb>hang quietly by a ſtring in the open Air, <lb></lb>to try how long the Fire would laſt with<lb></lb>out agitation when no Air was kept from <lb></lb>it. </s> <s>And we found that the Fire began to <lb></lb>go out firſt at the top and out-ſides of the <lb></lb>Coals; but inwards and near the bottom <lb></lb>the Fire continu'd viſible for above half <lb></lb>an hour, a great part of the Coals, eſpe<lb></lb>cially thoſe next the bottom, being burnt <lb></lb>to aſhes before the Fire went out. </s></p><p type="main"> <s>We cauſ'd likewiſe a piece of Iron to <lb></lb>be forg'd, of the bigneſs of a middle ſiz'd <lb></lb>Char-coal, and having made it red hot <pb xlink:href="013/01/121.jpg" pagenum="81"></pb>throughout; we cauſ'd it in the lately <lb></lb>mention'd Wier, to be ſpeedily convey'd <lb></lb>and ſhut up into the Receiver, being de<lb></lb>ſirous to try what would become of a <lb></lb>glowing Body, by reaſon of its texture <lb></lb>more vehemently hot then a burning <lb></lb>Coal of the ſame bigneſs, & yet unlike to <lb></lb>ſend forth ſuch copious & ſtifling Fumes: <lb></lb>But we could not obſerve any manifeſt <lb></lb>change upon the exſuction of the Air. <lb></lb></s> <s>The Iron began indeed to loſe its Fiery <lb></lb>redneſs at the top, but that ſeem'd to be <lb></lb>becauſe it was it the upper end ſomewhat <lb></lb>more ſlender then at the lower: The red<lb></lb>neſs, though it were in the day time, con<lb></lb>tinued viſible about four minutes; and <lb></lb>then, before it did quite diſ-appear, we <lb></lb>turn'd the Key of the Stop-cock but <lb></lb>could not diſcern any change of the Iron <lb></lb>upon the ruſhing in of the Air. </s> <s>Yet ſome <lb></lb>little remainders of Wax that ſtuck to <lb></lb>the Wier, and were turn'd into Fumes by <lb></lb>the heat of the neighboring Iron, ſeem'd <lb></lb>to afford a more plentiful, or at leaſt a <lb></lb>much more free expanded ſmoke when <lb></lb>the Air was ſuck'd out, then afterwards; <lb></lb>though allowance was made for the de<lb></lb>creaſing heat of the Iron. </s> <s>And laſtly, <lb></lb>notwithſtanding a conſiderable exſuction <pb xlink:href="013/01/122.jpg" pagenum="82"></pb>of the ambient Air, though not by far ſo <lb></lb>great a one as might have been made by <lb></lb>the Engine; and notwithſtanding the in<lb></lb>conſiderable diſſipation of the parts of the <lb></lb>Iron, the ſurrounding ſides of the Recei<lb></lb>ver were ſenſibly, and almoſt offenſively <lb></lb>heated by it; inſomuch that a pretty while <lb></lb>after the Iron was taken out, the ſides of <lb></lb>the Glaſs manifeſtly retain'd a warmth: <lb></lb>which would not be unfit to be conſider'd <lb></lb>by a Perſon at more leaſure then I am <lb></lb>now. </s></p><p type="main"> <s>BEing willing to try after this ſome<lb></lb><arrow.to.target n="marg14"></arrow.to.target><lb></lb>thing that would not cheriſh much <lb></lb>Fire at once, and would keep Fire much <lb></lb>longer then a Coal. </s> <s>We took a piece of <lb></lb>Match, ſuch as Souldiers uſe, of the thick<lb></lb>neſs of a Mans little Finger, or ſomewhat <lb></lb>thicker; and this being well lighted at <lb></lb>one end, was by a ſtring ſuſpended with <lb></lb>that end downwards in the cavity of the <lb></lb>Receiver which was immediately cloſ'd: <lb></lb>And yet by that time it could well be ſo, <lb></lb>the copious Fumes of the Match had neer <lb></lb>fill'd and darken'd the Receiver. </s> <s>Where<lb></lb>fore, leſt the Veſſel ſhould be endanger'd, <lb></lb>the Pump was nimbly ply'd, and a great <pb xlink:href="013/01/123.jpg" pagenum="83"></pb>deal of Air and Smoke mixt together was <lb></lb>drawn out, whereby the Receiver grow<lb></lb>ing more clear, we could diſcern the Fire <lb></lb>in the Match to burn more and more lan<lb></lb>guidly: And notwithſtanding that by the <lb></lb>diligence uſ'd in Pumping, it ſeem'd to <lb></lb>have room enough allow'd it to throw <lb></lb>out Fumes; yet after no long time it <lb></lb>ceaſ'd from being diſcernable either by its <lb></lb>Light or its Smoke. </s> <s>And though by <lb></lb>that we were invited to ſuppoſe it quite <lb></lb>extinguiſhed, yet we continu'd pumping <lb></lb>a while, in proſecution of another Expe<lb></lb>riment we were trying at the ſame time: <lb></lb>And this we did the more willingly be<lb></lb>cauſe of a ſuſpicion the Experiment a<lb></lb>bout the Coals might eaſily ſuggeſt, and <lb></lb>which the event declar'd not to have been <lb></lb>altogether groundleſs. </s> <s>For upon the <lb></lb>Admiſſion of the external Air, the Fire, <lb></lb>that ſeem'd to have gone out a pretty <lb></lb>while before, did preſently revive; and <lb></lb>being as it were refreſh d by the new Air, <lb></lb>and blown by the Wind made by that <lb></lb>Air in ruſhing in, it began again to ſhine <lb></lb>and diſſipate the neighboring Fuel into <lb></lb>Smoke as formerly. </s></p><pb xlink:href="013/01/124.jpg" pagenum="84"></pb><p type="margin"> <s><margin.target id="marg14"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 12.</s></p><p type="main"> <s>A While after we let down into <lb></lb><arrow.to.target n="marg15"></arrow.to.target><lb></lb>the Receiver together with a ligh<lb></lb>ted piece of Match, a great Bladder well <lb></lb>tyed at the Neck, but very lank, as not <lb></lb>containing actually much (if any thing) a<lb></lb>bove a Pint of Air, but being capable of <lb></lb>containing ten or twelve times as much. </s></p><p type="margin"> <s><margin.target id="marg15"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 13.</s></p><p type="main"> <s>Our ſcope in this Experiment was <lb></lb>partly to try whether or no the ſmoke of <lb></lb>the Match, repleniſhing the Receiver, <lb></lb>would be able to hinder the Dilatation of <lb></lb>the inward Air, upon the exſuction of the <lb></lb>Ambient. </s> <s>And partly to diſcover whe<lb></lb>ther the extinction of the Fire in the <lb></lb>Match did proceed from want of Air, or <lb></lb>barely from the preſſure of its own <lb></lb>Fumes, which for want of room to ex<lb></lb>pand themſelves in, might be ſuppoſ'd <lb></lb>to Recoyl upon the Fire, and ſo to <lb></lb>ſtifle it. </s></p><p type="main"> <s>The event of our tryal was, That <lb></lb>at the beginning of our Pumping the <lb></lb>Match appear'd well lighted, though <lb></lb>it had almoſt fill'd the Receiver with <lb></lb>its plentiful Fumes: But by degrees it <lb></lb>burnt more and more dimly, notwith<lb></lb>ſtanding that by the nimble drawing <pb xlink:href="013/01/125.jpg" pagenum="85"></pb>out the Air and Smoke, the Veſſel <lb></lb>were made leſs opacous, and leſs full of <lb></lb>compreſſing matter; as appeard by this, <lb></lb>That the longer we pump'd, the leſſer <lb></lb>Air and Smoke came out of the Cylin<lb></lb>der at the opening the Valve, and conſe<lb></lb>quently the leſs came into it before; yet <lb></lb>the Fire in the Match went but ſlowly <lb></lb>out. </s> <s>And when afterwards, to ſatisfie <lb></lb>our ſelves of its expiration, we had dar<lb></lb>ken'd the Room, and in vain endeavored <lb></lb>to diſcover any ſpark of Fire, as we could <lb></lb>not for ſome time before by the help of <lb></lb>Candles diſcern the leaſt riſing of Smoke, <lb></lb>we yet continued pumping ſix or ſeven <lb></lb>times; and after all that letting in the <lb></lb>Air, the ſeemingly dead Fire quickly <lb></lb>revived, and manifeſted its recovery by <lb></lb>Light and ſtore of Smoke, with the <lb></lb>latter of which it quickly began to re<lb></lb>pleniſh the Receiver. </s> <s>Then we fell <lb></lb>to pumping afreſh, and continued that <lb></lb>labour ſo long till the re-kindled <lb></lb>Match went out again: and thinking <lb></lb>it then fit not to ceaſe from Pum<lb></lb>ping ſo ſoon as before, we found that <lb></lb>in leſs then half a quarter of an hour the <lb></lb>Fire was got out for good and all, <pb xlink:href="013/01/126.jpg" pagenum="86"></pb>and paſt the poſſibility of being recover'd <lb></lb>by the re-admitted Air. </s></p><p type="main"> <s>Some Circumſtances, beſides thoſe al<lb></lb>ready mention'd, occurr'd in the making <lb></lb>of the Experiment, of which theſe are <lb></lb>the principal. </s></p><p type="main"> <s>Firſt, when the Receiver was full of <lb></lb>Smoke, if the Cylinder were emptied, <lb></lb>immediately upon the turning of the <lb></lb>Stop-cock, the Receiver would appear <lb></lb>manifeſtly darken'd to his eye that look'd <lb></lb>upon the light through it: and this dark<lb></lb>neſs was much leſs when the Receiver was <lb></lb>much leſs fill'd with Fumes: It was alſo <lb></lb>inſtantaneous, and ſeem'd to proceed from <lb></lb>a ſudden change of place and ſcituation <lb></lb>in the exhalations, upon the vent ſud<lb></lb>denly afforded them and the Air they <lb></lb>were mixt with, out of the Receiver into <lb></lb>the Cylinder. </s></p><p type="main"> <s>The next thing we obſerv'd was, a kinde <lb></lb>of <emph type="italics"></emph>Halo<emph.end type="italics"></emph.end> that appear'd a good while about <lb></lb>the Fire, and ſeem'd to be produced by <lb></lb>the ſurrounding Exhalations. </s></p><p type="main"> <s>And laſtly, it is remarkable, That even <lb></lb>when the Fumes ſeemed moſt to reple<lb></lb>niſh the Receiver, they did not ſenſibly <lb></lb>hinder the Air included in the Bladder <lb></lb>from dilating it ſelf after the ſame manner <pb xlink:href="013/01/127.jpg" pagenum="87"></pb>(for ought we could diſcern) as it would <lb></lb>have otherwiſe done: So that before the <lb></lb>Fire or the Match was quite extinct, the <lb></lb>Bladder appear'd ſwell'd at leaſt to ſix or <lb></lb>ſeven times its former capacity. </s></p><p type="main"> <s>Since the writing of theſe laſt Lines, <lb></lb>we took a ſmall Receiver, capable of <lb></lb>containing (by gueſs) about a pound and <lb></lb>a half of Water; and in the midſt of it <lb></lb>we ſuſpended a lighted Match, but though <lb></lb>within one minute of an hour (or there<lb></lb>abouts) from the putting in of the Match, <lb></lb>we had cemented on the Cover, yet we <lb></lb>could not make ſuch haſte, but that before <lb></lb>we began to pump, the Smoke had ſo <lb></lb>fill'd that ſmall Receiver, as for ought we <lb></lb>diſcern'd, to choke the Fire. </s> <s>And having <lb></lb>again and again reiterated the Experi<lb></lb>ment, it ſeem'd ſtill as at firſt, that we <lb></lb>could not cloſe up the Veſſel and pump <lb></lb>out all the Fumes time enough to reſcue <lb></lb>the Fire from Extinction; whereupon we <lb></lb>made uſe of this Expedient. </s> <s>Aſſoon as <lb></lb>we had pump'd once or twice, we ſudden<lb></lb>ly turn'd the Key, and thereby gave acceſs <lb></lb>to the excluded Air, which ruſhing vio<lb></lb>lently in, as if it had been forced thorow <lb></lb>a pair of Bellows, did both drive away <lb></lb>the aſhes, fill the Glaſs with freſh Air, and <pb xlink:href="013/01/128.jpg" pagenum="88"></pb>by blowing the almoſt extinguiſh'd Fire, <lb></lb>re-kindl'd it, as appear'd by the Matches <lb></lb>beginning again to ſmoke, which before it <lb></lb>had ceaſ'd to do; we having by this <lb></lb>means obtain'd a lighted Match in the <lb></lb>Receiver, without being reduc'd to ſpend <lb></lb>time to cloſe it up, commanded the Air <lb></lb>to be immediatly pump'd out, and found <lb></lb>that upon the exſuction of it, the Match <lb></lb>quickly left ſmokeing, as it ſeem'd, by <lb></lb>reaſon of the abſence of the Air; and <lb></lb>yet if ſome urgent occaſions had not hin<lb></lb>der'd us, we would for greater ſecurity <lb></lb>have try'd, whether or no the Match re<lb></lb>kindled as formerly, would ſmoke much <lb></lb>longer, in caſe of no exſuction of the am<lb></lb>bient Air. </s></p><p type="main"> <s>TO try diverſe things at once, <lb></lb><arrow.to.target n="marg16"></arrow.to.target><lb></lb>and particularly whether Fire, <lb></lb>though we found it would not long laſt, <lb></lb>might not yet be produced in our eva<lb></lb>cuated Receiver: We took a Piſtol of <lb></lb>about a Foot in length, and having <lb></lb>firmly tyed it to a ſtick almoſt as long as <lb></lb>the Cavity of the Receiver, we very <lb></lb>carefully prim'd it with well dry'd Gun<lb></lb>powder, and then cocking it, we ty'd to <pb xlink:href="013/01/129.jpg" pagenum="89"></pb>the Tricker one end of a ſtring, whoſe <lb></lb>other end was faſten'd to the Key former<lb></lb>ly mention'd to belong to the Cover of <lb></lb>our Receiver. </s> <s>This done, we convey'd <lb></lb>the Piſtol, together with the annexed <lb></lb>Staff, into the Veſſel: which being cloſ'd <lb></lb>up, and empty'd after the uſual man<lb></lb>ner, we began to turn the Key in the <lb></lb>Cover; and thereby ſhortning the ſtring <lb></lb>that reach'd from it to the Piſtol, we <lb></lb>pull'd aſide the Tricker, and obſerv'd, <lb></lb>that according to our expectation the <lb></lb>force of the Spring of the Lock was <lb></lb>not ſenſibly abated by the abſence of <lb></lb>the Air. (from whoſe <emph type="italics"></emph>impetus<emph.end type="italics"></emph.end> yet ſome <lb></lb>Modern Naturaliſts would derive the <lb></lb>cauſe of the motion of Reſtitution in <lb></lb>ſolid Bodies) For the Cock falling <lb></lb>with its wonted violence upon the Steel, <lb></lb>ſtruck out of it as many and as conſpi<lb></lb>cuous parts of Fire, as, for ought we <lb></lb>could perceive, it would have done in <lb></lb>the open Air. </s> <s>Repeating this Experi<lb></lb>ment divers times, we alſo obſerved <lb></lb>whether or no there would appear <lb></lb>any conſiderable Diverſity in the <lb></lb>Motion of the ſhining Sparks in a <lb></lb>place where the remaining Aire was <lb></lb>ſo much rarified, but could not perceive <pb xlink:href="013/01/130.jpg" pagenum="100"></pb>but that they moved ſome of them up<lb></lb>wards, as well as ſome of them down<lb></lb>wards, and ſome of them ſide-ways, as <lb></lb>they are wont to do, when upon ſuch col<lb></lb>liſions they fly out in the open Air. </s></p><p type="margin"> <s><margin.target id="marg16"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 14.</s></p><p type="main"> <s>We likewiſe cauſ'd a piece of Steel to <lb></lb>be made of the form and bigneſs of the <lb></lb>Flint, in whoſe place we put it, and then <lb></lb>the Piſtol being cock'd and conveyed in<lb></lb>to the Receiver, the Trigger was pull'd <lb></lb>after the Air was drawn out: And though <lb></lb>the place were purpoſely ſomewhat dar<lb></lb>ken'd, yet there appear'd not upon the <lb></lb>ſtriking of the two Steels againſt each o<lb></lb>ther the leaſt ſpark of Fire: Nor did we <lb></lb>expect any (having before in vain attem<lb></lb>pted to ſtrike Fire this way in the open <lb></lb>Air) though we thought fit to make the <lb></lb>Experiment to undeceive thoſe who fan<lb></lb>cy in rarified Air, I know not what ſtrange <lb></lb>diſpoſition, to take Fire upon a much <lb></lb>ſlighter occaſion then this Experiment <lb></lb>afforded. </s> <s>We have indeed found, that <lb></lb>by the dextrous Colliſion of two har<lb></lb>den'd pieces of Steel, ſtore of ſparks <lb></lb>may be ſtruck out: But that was done with <lb></lb>ſuch vehement percuſſion of the edges of <lb></lb>the two Steels, as could not well be com<lb></lb>paſſ'd in our Receiver. </s></p><pb xlink:href="013/01/131.jpg" pagenum="101"></pb><p type="main"> <s>But the chief thing we deſign'd to do <lb></lb>with our Piſtol, was, To obſerve whe<lb></lb>ther Gun-powder would take Fire in our <lb></lb>empty'd and cloſely ſtop'd Glaſs? </s> <s>Whe<lb></lb>ther the expanſion of the Flame would be <lb></lb>conſiderably varied by the abſence of ſo <lb></lb>much of the ambient Air as was drawn <lb></lb>out of the Receiver? </s> <s>and whether the <lb></lb>Flame would diffuſe it ſelf upward, as it is <lb></lb>wont, notwithſtanding its not having a<lb></lb>bout it the uſual proportion of Air to <lb></lb>force it up? </s> <s>And though moſt of our at<lb></lb>tempts to fire the Gun-powder in the <lb></lb>Pan of the Piſtol ſucceeded not, becauſe <lb></lb>we were fain to let it hang almoſt perpen<lb></lb>dicular in the Receiver; whereby the <lb></lb>Powder was ſhaken down before the <lb></lb>ſparks could reach it: yet once the Ex<lb></lb>periment ſucceeded, and the kindled <lb></lb>Powder ſeem'd to make a more expanded <lb></lb>Flame then it would have done in the <lb></lb>open Air, but mounted upwards accord<lb></lb>ing to its wont, whether by reaſon of that <lb></lb>little portion of Air, which in ſpight of <lb></lb>our pumping remained in the Receiver, or <lb></lb>for any other cauſe, we have not now the <lb></lb>leiſure to conſider. </s> <s>But we muſt not for<lb></lb>get, that upon the extinction of the Flame <lb></lb>the Receiver appear'd darken'd with <pb xlink:href="013/01/132.jpg" pagenum="102"></pb>ſmoke, which ſeem'd to move freely up <lb></lb>and down, and upon the letting in the Air <lb></lb>at the Stop-cock began to circulate much <lb></lb>faſter then before. </s> <s>We wonld have made <lb></lb>more obſervations concerning this Flame, <lb></lb>but that of two or three attempts we <lb></lb>afterwards made to repeat the kindling of <lb></lb>Powder, not any one ſucceeded; and <lb></lb>we have not the leaſure to dwell long up<lb></lb>on one kinde of Tryals. </s></p><p type="main"> <s>TO theſe Experiments concerning Fire <lb></lb><arrow.to.target n="marg17"></arrow.to.target><lb></lb>we added another, which, though it ſuc<lb></lb>ceded not, may perhaps without imper<lb></lb>tinency be recorded: partly becauſe that <lb></lb>(as we have in another Treatiſe amply de<lb></lb>clar'd) it is uſefull to recite what Experi<lb></lb>ments miſcarry as well as what ſucceed. <lb></lb></s> <s>And partly alſo becauſe it is very poſſible <lb></lb>that what we endeavored in vaine, may be <lb></lb>performed by Your Lordſhip, or ſome <lb></lb>other <emph type="italics"></emph>Virtuoſo<emph.end type="italics"></emph.end> that ſhall have ſlancker <lb></lb>Veſſells then we had, and more Sunny <lb></lb>dayes then the preſent Winter allows <lb></lb>us. </s></p><p type="margin"> <s><margin.target id="marg17"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 15.</s></p><p type="main"> <s>We convey'd then into one of our ſmall <lb></lb>Receivers a piece of matter combuſtible, <lb></lb>dry and black (experience declaring things <pb xlink:href="013/01/133.jpg" pagenum="103"></pb>of that colour to be moſt eaſily kindled) <lb></lb>& carefully cloſing the Veſſel we brought <lb></lb>it to a Window at which the Sun, not very <lb></lb>faire from the Meridian, ſhone in very free<lb></lb>ly: then drawing out the Aire with ſpeed <lb></lb>united the Sun-beames with a burning <lb></lb>Glaſs upon the combuſtible matter which <lb></lb>began immediatly to ſend forth a Smoke <lb></lb>that quickly darkned the Receiver, but <lb></lb>notwithſtanding all our care and diligence <lb></lb>the externall Aire got in ſo faſt that after <lb></lb>diverſe tryals we were fayne to leave off <lb></lb>the Experiment in that Glaſſe and induc'd <lb></lb>to make tryall of it in our great Re<lb></lb>ceiver. </s></p><p type="main"> <s>Haveing then after ſome difficulty <lb></lb>lodg'd the combuſtible matter in the ca<lb></lb>vity of this Veſſell in ſuch manner as that <lb></lb>it was almoſt contiguous to that ſide <lb></lb>thereof that was next the Sun, we did en<lb></lb>deavor with a pretty large burning Glaſs <lb></lb>to kindle it, but found, as we fear'd, <lb></lb>That by reaſon of the thickneſs of the <lb></lb>Glaſs, (which was alſo of a leſs pure and <lb></lb>leſs Diaphanous matter then the o<lb></lb>ther) the Sun-beams thrown in by the <lb></lb>burning Glaſs, were in their paſſage <lb></lb>ſo Diſlocated and Scattered (not now to <lb></lb>mention thoſe many that being reflected, <pb xlink:href="013/01/134.jpg" pagenum="104"></pb>I could not pierce into the cavity of the <lb></lb>Receiver) that we could not poſſibly u<lb></lb>nite enough of them to kindle the matter, <lb></lb>nor ſo much as to make it ſenſibly ſmoke. <lb></lb></s> <s>Yet we hope that the ſeeing whether Bo<lb></lb>dies (other then Gun-powder) may be <lb></lb>kindled, and what would happen to them <lb></lb>when ſet on fire, in a place in great mea<lb></lb>ſure devoid of Air, may prove ſo Lucife<lb></lb>rous an Experiment, that when the Sea<lb></lb>ſon is more favorable we ſhall, God per<lb></lb>mitting, make further tryal of it, and ac<lb></lb>quaint Your Lordſhip with the Event, if <lb></lb>it prove proſperous. </s> <s>In the mean time <lb></lb>we ſhall paſs on to other Experiments, <lb></lb>aſſoon as we have advertiſ'd Your Lord<lb></lb>ſhip that we have forborn to make ſuch <lb></lb>Reflections upon the ſeveral Experiments <lb></lb>we have ſet down concerning Fire, as the <lb></lb>matter would have eaſily enough afford<lb></lb>ed, and Your Lordſhip may perhaps have <lb></lb>expected. </s> <s>But I made the leſs ſcruple to <lb></lb>forbear the annexing of Speculations to <lb></lb>theſe Recitals, becauſe <emph type="italics"></emph>Carneades<emph.end type="italics"></emph.end> & <emph type="italics"></emph>Eleu<lb></lb>therius<emph.end type="italics"></emph.end> have in ſome Dialogues concern<lb></lb>ing Heat and Flame, which were laſt year <lb></lb>ſeen by ſome Friends, and may be, when <lb></lb>you pleaſe, commanded by You, men-<pb xlink:href="013/01/135.jpg" pagenum="105"></pb>tion'd divers of my Thoughts and Expe<lb></lb>riments concerning Fire. </s></p><p type="main"> <s>WE deſigned to try whether or no <lb></lb><arrow.to.target n="marg18"></arrow.to.target><lb></lb>divers Magnetical Experiments <lb></lb>would exhibit any unuſual <emph type="italics"></emph>Phænomena,<emph.end type="italics"></emph.end><lb></lb>being made in our Evacuated Receiver <lb></lb>inſtead of the open Air: But for want of <lb></lb>leiſure and conveniency to proſecute ſuch <lb></lb>Tryals, we were induced to reſerve the <lb></lb>reſt for an other time, and to content our <lb></lb>ſelves with making that which follows. <lb></lb></s> <s>We convey'd into the Receiver a little <lb></lb>Pedeſtal of Wood, in the midſt of which <lb></lb>was perpendicularly erected a ſlender <lb></lb>Iron, upon whoſe ſharp point an excited <lb></lb>Needle of Steel purpoſely made, and of <lb></lb>about five Inches long, was ſo placed <lb></lb>that hanging in an <emph type="italics"></emph>Æquilibrium<emph.end type="italics"></emph.end> it could <lb></lb>move freely towards either hand. </s> <s>Then <lb></lb>the Air being after the uſual manner <lb></lb>pumped out, we apply'd a Load-ſtone <lb></lb>moderately vigorous to the out-ſide of <lb></lb>of the Glaſs, and found that it Attracted <lb></lb>or Repell'd the ends of the Needle, accor<lb></lb>ding to the Laws Magnetical, without <lb></lb>any remarkable difference from what the <lb></lb>ſame Load-ſtone would have done had <pb xlink:href="013/01/136.jpg" pagenum="106"></pb>none of the Air been drawn away from a<lb></lb>bout the Needle, which when the Load<lb></lb>ſtone was removed, after ſome tremu<lb></lb>lous Vibrations to and fro, reſted in a po<lb></lb>ſition wherein it look'd North and <lb></lb>South. </s></p><p type="margin"> <s><margin.target id="marg18"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 16</s></p><p type="main"> <s>PRoceed we now to the mention of <lb></lb><arrow.to.target n="marg19"></arrow.to.target><lb></lb>that Experiment, whereof the ſatiſ<lb></lb>factory tryal was the principal Fruit I <lb></lb>promiſ'd my ſelf from our Engine. </s> <s>It <lb></lb>being then ſufficiently known, that, in <lb></lb>the Experiment <emph type="italics"></emph>De Vacuo,<emph.end type="italics"></emph.end> the Quick<lb></lb>ſilver in the Tube is wont to remain ele<lb></lb>vated, above the ſurface of that whereon <lb></lb>it leans, about 27 digits: I conſidered, <lb></lb>that, if the true and onely reaſon why the <lb></lb>Quick-ſilver falls no lower, be, that at <lb></lb>that Altitude, the Mercurial Cylinder in <lb></lb>the Tube, is an <emph type="italics"></emph>Æquilibrium<emph.end type="italics"></emph.end> with the <lb></lb>Cylinder of Air, ſuppoſ'd to reach from <lb></lb>the adjacent Mercury to the top of the <lb></lb>Atmoſphere: If this Experiment could <lb></lb>be try'd out of the Atmoſphere, the <lb></lb>Quick-ſilver in the Tube would fall <lb></lb>down to a levell with that in the Veſſel, <lb></lb>ſince then there would be no preſſure up<lb></lb>on the Subjacent, to reſiſt the weight of <pb xlink:href="013/01/137.jpg" pagenum="107"></pb>the Incumbent Mercury. </s> <s>Whence I in<lb></lb>ferr'd (as eaſily I might) that, if the Ex<lb></lb>periment could be try'd in our Engine, the <lb></lb>Quick-ſilver would ſubſide below 27 Di<lb></lb>gits, in proportion to the exſuction of <lb></lb>Air, that ſhould be made out of the Re<lb></lb>ceiver. </s> <s>For, as when the Air is ſhut in<lb></lb>to the Receiver, it does (according to <lb></lb>what hath above been taught) continue <lb></lb>there as ſtrongly compreſſ'd, as it did <lb></lb>whil'ſt all the incumbent Cylinder of the <lb></lb>Atmoſphere lean'd immediatly upon it; <lb></lb>becauſe the Glaſs, wherein it is pent up, <lb></lb>hinders it to deliver it ſelf, by an expanſi<lb></lb>on of its parts, from the preſſure where<lb></lb>with it was ſhut up. </s> <s>So, if we could per<lb></lb>fectly draw the Air out of the Receiver, <lb></lb>it would conduce as well to our purpoſe, <lb></lb>as if we were allow'd to try the Experi<lb></lb>ment beyond the Atmoſphere. </s></p><p type="margin"> <s><margin.target id="marg19"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 17.</s></p><p type="main"> <s>Wherefore (after having ſurmounted <lb></lb>ſome little difficulties which occurr'd at <lb></lb>the beginning) the Experiment was made <lb></lb>after this manner. </s> <s>We took a ſlender and <lb></lb>very curiouſly blown Cylinder of Glaſs, <lb></lb>of near three Foot in length, and whoſe <lb></lb>bore had in Diameter a quarter of an Inch, <lb></lb>wanting a hairs breadth: This Pipe being <lb></lb>Hermetically ſeal'd at one end, was, at <pb xlink:href="013/01/138.jpg" pagenum="108"></pb>the other, fill'd with Quick-ſilver, care <lb></lb>being taken in the filling, that as few <lb></lb>bubles as was poſſible ſhould be left in the <lb></lb>Mercury: Then the Tube being ſtopt <lb></lb>with the Finger and inverted, was open'd, <lb></lb>according to the manner of the Experi<lb></lb>ment, into a ſomewhat long and ſlender <lb></lb>Cylindrical Box (inſtead of which we now <lb></lb>are wont to uſe a Glaſs of the ſame form) <lb></lb>half fill'd with Quick-ſilver: And ſo, the <lb></lb>liquid metal being ſuffered to ſubſide, and <lb></lb>a piece of Paper being paſted on levell <lb></lb>with its upper ſurface, the Box and Tube <lb></lb>and all were by ſtrings carefully let down <lb></lb>into the Receiver, and then, by means of <lb></lb>the hole formerly mention'd to be left in <lb></lb>the Cover, the ſaid Cover was ſlip't along <lb></lb>as much of the Tube as reach'd above the <lb></lb>top of the Receiver; And the Interval, <lb></lb>left betwixt the ſides of the Hole and <lb></lb>thoſe of the Tube, was very exquiſitely <lb></lb>fill'd up with melted (but not over hot) <lb></lb>Diachylon; and the round chink, betwixt <lb></lb>the Cover and the Receiver, was likewiſe <lb></lb>very carefully cloſ'd up: Upon which clo<lb></lb>ſure there appear'd not any change in the <lb></lb>height of the Mercurial Cylinder; no <lb></lb>more, then if the interpoſ'd Glaſs Recei<lb></lb>ver did not hinder the immediate preſſure <pb xlink:href="013/01/139.jpg" pagenum="109"></pb>of the ambient Atmoſphere upon the <lb></lb>incloſed Air; which hereby appears to <lb></lb>bear up on the Mercury, rather by virtue <lb></lb>of its ſpring, then of its weight: ſince its <lb></lb>weight cannot be ſuppoſ'd to amount to <lb></lb>above two or three Ounces, which is in<lb></lb>conſiderable in compariſon of ſuch a Cy<lb></lb>linder of Mercury as it would keep from <lb></lb>ſubſiding. </s></p><p type="main"> <s>All things being thus in a readineſs, the <lb></lb>Sucker was drawn down; and, immedi<lb></lb>ately upon the egreſs of a Cylinder of <lb></lb>Air out of the Receiver; the Quick-ſilver <lb></lb>in the Tube did, according to expectati<lb></lb>on, ſubſide: and notice being carefully <lb></lb>taken (by a mark faſten'd to the outſide) <lb></lb>of the place where it ſtopt, we cauſ'd him <lb></lb>that manag'd the Pump to pump again, <lb></lb>and mark'd how low the Quick-ſilver fell <lb></lb>at the ſecond exſuction; but continuing <lb></lb>this work, we were quickly hindred from <lb></lb>accurately marking the Stages made by <lb></lb>the Mercury in its deſcent, becauſe it ſoon <lb></lb>ſunk below the top of the Receiver; ſo <lb></lb>that we could thenceforward mark it no <lb></lb>other ways then by the eye. </s> <s>And thus, <lb></lb>continuing the labor of pumping for a<lb></lb>bout a quarter of an hour, we found our <lb></lb>ſelves unable to bring the Quick-ſilver in <pb xlink:href="013/01/140.jpg" pagenum="110"></pb>the Tube totally to ſubſide; becauſe, <lb></lb>when the Receiver was conſiderably em<lb></lb>pty'd of its Air, and conſequently that <lb></lb>little that remain'd grown unable to reſiſt <lb></lb>the Irruption of the external, that Air <lb></lb>would (in ſpight of whatever we could <lb></lb>do) preſs in at ſome little Avenue or <lb></lb>other; and though much could not there<lb></lb>at get in, yet a little was ſufficient to coun<lb></lb>terballance the preſſure of ſo ſmall a Cy<lb></lb>linder of Quick-ſilver, as then remain'd <lb></lb>in the Tube. </s></p><p type="main"> <s>Now (to ſatisfie our ſelves further, that <lb></lb>the failing of the Quick-ſilver in the <lb></lb>Tube to a determinate height, proceeds <lb></lb>from the <emph type="italics"></emph>Æquilibrium,<emph.end type="italics"></emph.end> wherein it is at <lb></lb>that height with the external Air, the one <lb></lb>gravitating, the other preſſing with equal <lb></lb>force upon the ſubjacent Mercury) we Re<lb></lb>turned the Key and let in ſome new Air; <lb></lb>upon which the Mercury immediatly be<lb></lb>gan to aſcend (or rather to be impell'd up<lb></lb>wards) in the Tube, and continu'd aſcend<lb></lb>ing, till having Return'd the Key it im<lb></lb>mediatly reſted at the height which it had <lb></lb>then attain'd: And ſo, by Turning and <lb></lb>Returning the Key, we did ſeveral times <lb></lb>at pleaſure impel it upwards, and check its <lb></lb>aſcent. </s> <s>And laſtly, having given a free <pb xlink:href="013/01/141.jpg" pagenum="111"></pb>egreſs at the Stop-cock to as much of the <lb></lb>external Air as would come in, the Quick<lb></lb>ſilver was impell'd up almoſt to its firſt <lb></lb>height: I ſay almoſt, becauſe it ſtopt <lb></lb>near a quarter of an Inch beneath the Pa<lb></lb>per mark formerly mention'd; which we <lb></lb>aſcrib'd to this, That there was (as is u<lb></lb>ſual in this Experiment) ſome little Parti<lb></lb>cles of Air engag'd among thoſe of the <lb></lb>Quick-ſilver; which Particles, upon the <lb></lb>deſcent of the Quick-ſilver, did manifeſt<lb></lb>ly riſe up in Bubbles towards the top of <lb></lb>the Tube, and by their preſſure, as well <lb></lb>as by leſſening the Cylinder by as much <lb></lb>room as they formerly took up in it, hin<lb></lb>der'd the Quick-ſilver from regaining its <lb></lb>firſt height. </s></p><p type="main"> <s>This Experiment was a few days after <lb></lb>repeated in the preſence of thoſe excellent <lb></lb>and deſervedly Famous Mathematick <lb></lb>Profeſſors, Dr. <emph type="italics"></emph>Wallis,<emph.end type="italics"></emph.end> Dr. <emph type="italics"></emph>Ward,<emph.end type="italics"></emph.end> and Mr. <lb></lb><emph type="italics"></emph>Wren,<emph.end type="italics"></emph.end> who were pleaſed to Honor it with <lb></lb>their Preſence: And whom I name, both <lb></lb>as juſtly counting it an Honor to be <lb></lb>known to them, and as being glad of ſuch <lb></lb>Judicious and illuſtrious Witneſſes of our <lb></lb>Experiment; and 'twas by their gueſs that <lb></lb>the top of the Quick-ſilver in the Tube <lb></lb>was defin'd to be brought within an Inch <pb xlink:href="013/01/142.jpg" pagenum="112"></pb>of the ſurface of that in the Veſſel. </s></p><p type="main"> <s>And here, for the Illuſtration of the <lb></lb>foregoing Experiment, it will not be a<lb></lb>miſs to mention ſome other particulars <lb></lb>relating to it. </s></p><p type="main"> <s>Firſt then, When we endeavor'd to <lb></lb>make the Experiment with the Tube <lb></lb>cloſ'd at one end with <emph type="italics"></emph>Diachylon<emph.end type="italics"></emph.end> inſtead <lb></lb>of an Hermetical Seal; we perceiv'd, that <lb></lb>upon the drawing of ſome of the Air out <lb></lb>of the Receiver, the Mercury did indeed <lb></lb>begin to fall, but continu'd afterwards to <lb></lb>ſubſide, though we did not continue pum<lb></lb>ping. </s> <s>Whence it appear'd, that though <lb></lb>the <emph type="italics"></emph>Diachylon<emph.end type="italics"></emph.end> that ſtopt the end of the <lb></lb>Tube were ſo thick and ſtrong, that the <lb></lb>external Air could not preſs it in (as expe<lb></lb>rience taught us that it would have done, <lb></lb>if there had been but little of it) yet the <lb></lb>ſubt'ler parts of it were able (though <lb></lb>ſlowly) to inſinuate themſelves through <lb></lb>the very body of the Plaiſter, which it <lb></lb>ſeems was of ſo cloſe a Texture, as that <lb></lb>which we mention'd our ſelves to have <lb></lb>ſucceſsfully made uſe of in the Experi<lb></lb>ment <emph type="italics"></emph>De Vacuo<emph.end type="italics"></emph.end> ſome years ago. </s> <s>So that <lb></lb>now we begin to ſuſpect, that perhaps one <lb></lb>Reaſon, why we cannot perfectly pump <lb></lb>out the Air, may be, that when the Veſſel <pb xlink:href="013/01/143.jpg" pagenum="113"></pb>is almoſt empty, ſome of the ſubtler <lb></lb>parts of the external Air may, by the <lb></lb>preſſure of the Atmoſphere, be ſtrain'd <lb></lb>through the very body of the <emph type="italics"></emph>Diachylon<emph.end type="italics"></emph.end><lb></lb>into the Receiver. </s> <s>But this is onely con<lb></lb>jecture: </s></p><p type="main"> <s>Another Circumſtance of our Expe<lb></lb>riment was this, That, if (when the <lb></lb>Quick-ſilver in the Tube was fallen low) <lb></lb>too much ingreſs were, at the hole of the <lb></lb>Stop-cock, ſuddenly permitted to the ex<lb></lb>ternal Air; it would ruſh in with that vio<lb></lb>lence, and bear ſo forcibly upon the ſur<lb></lb>face of the ſubjacent Quick-ſilver, that <lb></lb>it would impel it up into the Tube rudely <lb></lb>enough to endanger the breaking of the <lb></lb>Glaſs. </s></p><p type="main"> <s>We formerly mention'd, that the <lb></lb>Quick-ſilver did not in its deſcent fall as <lb></lb>much at a time after the two or three firſt <lb></lb>exſuctions of the Air, as at the beginning: <lb></lb>For, having mark'd its ſeveral Stages up<lb></lb>on the Tube, we found, that at the firſt <lb></lb>ſuck it deſcended an Inch and 3/8, and at the <lb></lb>ſecond an Inch and 1/8; and when the Veſ<lb></lb>ſel was almoſt empty'd, it would ſcarce at <lb></lb>one exſuction be drawn down above the <lb></lb>breadth of a Barly-corn. </s> <s>And indeed we <lb></lb>found it very difficult to meaſure in what <pb xlink:href="013/01/144.jpg" pagenum="114"></pb>proportion theſe decrements of the Mer<lb></lb>curial Cylinder did proceed: partly be<lb></lb>cauſe (as we have already intimated) the <lb></lb>Quick ſilver was ſoon drawn below the <lb></lb>top of the Receiver: and partly becauſe, <lb></lb>upon its deſcent at each exſuction, it <lb></lb>would immediatly reaſcend a little up<lb></lb>wards; either by reaſon of the leaking of <lb></lb>the Veſſel at ſome imperceptible hole or <lb></lb>other, or by reaſon of the motion of <lb></lb>Reſtitution in the Air, which, being ſome<lb></lb>what compreſt by the fall as well as weight <lb></lb>of the Quick ſilver, would repell it a lit<lb></lb>tle upwards, and make it vibrate a little up <lb></lb>and down, before they could reduce each <lb></lb>other to ſuch an <emph type="italics"></emph>Æquilibrium<emph.end type="italics"></emph.end> as both <lb></lb>might reſt in. </s> <s>But though we could not <lb></lb>hitherto make obſervations accurate e<lb></lb>nough concerning the meaſures of the <lb></lb>Quick-ſilver's deſcent, to reduce them in<lb></lb>to any <emph type="italics"></emph>Hypotheſis,<emph.end type="italics"></emph.end> yet would we not diſ<lb></lb>courage any from attempting it: ſince, if it <lb></lb>could be reduc'd to a certainty, tis proba<lb></lb>ble that the diſcovery would not be un<lb></lb>uſeful. </s></p><p type="main"> <s>And, to illuſtrate this matter a little <lb></lb>more, we will adde, That we made a ſhift <lb></lb>to try the Experiment in one of our above <lb></lb>mention'd ſmall Receivers, not containing <pb xlink:href="013/01/145.jpg" pagenum="115"></pb>a Quart; but that (agreeably to what we <lb></lb>formerly obſerved) we found it as difficult <lb></lb>to bring this to be quite empty as to eva<lb></lb>cuate the greater; the leaſt external Air <lb></lb>that could get in (and we could not poſſi<lb></lb>bly keep it all perfectly out) ſufficing in ſo <lb></lb>ſmall a Veſſel to diſplay a conſiderable <lb></lb>preſſure upon the ſurface of the Mercury, <lb></lb>and thereby hinder that in the Tube from <lb></lb>falling to a level with it. </s> <s>But this is remark<lb></lb>able, that having two or three times try'd <lb></lb>the Experiment in that ſmall Veſſel, upon <lb></lb>the very firſt Cylinder of Air that was <lb></lb>drawn out of the Receiver, the Mercury <lb></lb>fell in the Tube 18 Inches and a half, and <lb></lb>at another 19 Inches and a half. </s></p><p type="main"> <s>But, on this occaſion, I hold it not un<lb></lb>fit to give Your Lordſhip notice that I <lb></lb>hop'd, from the deſcent of the Quick<lb></lb>ſilver in the Tube upon the firſt ſuck, to <lb></lb>derive this advantage: that I ſhould thence <lb></lb>be enabled to give a near gueſs at the pro<lb></lb>portion of force betwixt the preſſure of <lb></lb>the Air (according to its various ſtates, as <lb></lb>to Denſity and Rarefaction) and the gra<lb></lb>vity of Quick-ſilver, then hitherto has <lb></lb>been done. </s> <s>For in our Experiment there <lb></lb>are diverſe things given, that may be <lb></lb>made uſe of towards ſuch a diſcovery. <pb xlink:href="013/01/146.jpg" pagenum="116"></pb>For firſt we may know the capacity of the <lb></lb>Receiver wherein the Experiment is <lb></lb>made, ſince, by filling it with water, we <lb></lb>may eaſily compute how many Quarts, or <lb></lb>Meaſures of any other denomination, it <lb></lb>contains of Air; which Air, when ſhut <lb></lb>up in the Veſſel, may be ſuppoſ'd to have <lb></lb>a preſſure equal to that of the Atmo<lb></lb>ſphere; ſince it is able to keep the Quick<lb></lb>ſilver in the Tube from falling any lower <lb></lb>then it did in the free and open Air. </s> <s>Next <lb></lb>here is given us the capacity of the braſs <lb></lb>Cylinder empty'd by the drawing down <lb></lb>of the Sucker (its bore and height being <lb></lb>mention'd in the deſcription of our Pump) <lb></lb>whereby we may come to know how <lb></lb>much of the Air contain'd in the Recei<lb></lb>ver is drawn out at the firſt ſuck. </s> <s>And <lb></lb>we may alſo eaſily define, either in weight <lb></lb>or cubick meaſures the Cylinder of <lb></lb>Quick-ſilver that anſwers to the Cy<lb></lb>linder of Air lately mention'd (that <lb></lb>Mercuriall Cylinder being in our En<lb></lb>gine computable by deducting from <lb></lb>the entire altitude or that Cylinder of <lb></lb>Quick-ſilver, the altitude at which it reſts <lb></lb>upon the firſt exſuction.) But though, if <lb></lb>this Experiment were very watchfully <lb></lb>try'd in Veſſels of ſeveral ſizes, and the <pb xlink:href="013/01/147.jpg" pagenum="117"></pb>various deſcents of the Quick-ſilver com<lb></lb>par'd among themſelves, 'tis not impro<lb></lb>bable that ſome ſuch thing as we hop'd for <lb></lb>may thereby be diſcover'd. </s> <s>Yet becauſe <lb></lb>not onely the ſolid contents of as much <lb></lb>of the Glaſs-tube as remains within the <lb></lb>concave ſurface of the Receiver, and <lb></lb>(which is more difficult) the varying con<lb></lb>tents of the Veſſel containing the Mer<lb></lb>cury, and of as much of the Mercury it <lb></lb>ſelf as is not in the Tube, muſt be dedu<lb></lb>cted out of the capacity of the Receiver; <lb></lb>but there muſt alſo an allowance be made <lb></lb>for this, that the Cylinder that is empty'd <lb></lb>by the drawing down of the Sucker, and <lb></lb>comes to be fill'd upon the letting of the <lb></lb>Air out of the Receiver into it, is not ſo <lb></lb>repleniſh'd with Air as the Receiver it ſelf <lb></lb>at firſt was: becauſe there paſſes no more <lb></lb>Air out of the Receiver into the Cylin<lb></lb>der, then is requiſite to reduce the Air in <lb></lb>the cavity of the Cylinder, and in that of <lb></lb>the Receiver to the ſame meaſure of dila<lb></lb>tation: Becauſe of theſe (I ſay) and ſome <lb></lb>other difficulties that require more skill in <lb></lb>Mathematicks then I pretend to, and much <lb></lb>more leaſure then my preſent occaſions <lb></lb>would allow me, I was willing to refer the <lb></lb>nicer conſideration of this matter to ſome <pb xlink:href="013/01/148.jpg" pagenum="118"></pb>of our Learned and Acurate Mathema<lb></lb>ticians, thinking it enough for me to have <lb></lb>given the Hint already ſuggeſted. </s></p><p type="main"> <s>For further confirmation of what hath <lb></lb>been delivered, we likewiſe tryed the Ex<lb></lb>periment in a Tube of leſs then two foot <lb></lb>long: and, when there was ſo much Air <lb></lb>drawn out of the Veſſel, that the remain<lb></lb>ing Air was not able to counterballance <lb></lb>the Mercurial Cylinder, the Quick-ſilver <lb></lb>in the Tube ſubſided ſo viſibly, that (the <lb></lb>Experiment being try'd in the little Veſ<lb></lb>ſel lately mention'd) at the firſt ſuck it <lb></lb>fell above a ſpan, and was afterwards <lb></lb>drawn lower and lower for a little while; <lb></lb>and the external Air being let in upon it, <lb></lb>impell'd it up again almoſt to the top of <lb></lb>the Tube: So little matters it how heavy <lb></lb>or light the Cylinder of Quick ſilver to <lb></lb>ſubſide is, provided its gravity over<lb></lb>power the preſſure of as much external <lb></lb>Air as bears upon the ſurface of that Mer<lb></lb>cury into which it is to fall. </s></p><p type="main"> <s>Laſtly we alſo obſerv'd, That if (when <lb></lb>the Mercury in the Tube had been drawn <lb></lb>down, and by an Ingreſs permitted to the <lb></lb>external Air, impell'd up again to its for<lb></lb>mer height) there were ſome more Air <lb></lb>thruſt up by the help of the Pump into <pb xlink:href="013/01/149.jpg" pagenum="119"></pb>the Receiver, the Quick-ſilver in the Tube <lb></lb>would aſcend much above the wonted <lb></lb>height of 27 digits, and immediatly up<lb></lb>on the letting out of that Air would fall a<lb></lb>gain to the height it reſted at before. </s></p><p type="main"> <s>Your Lordſhip will here perhaps expect, <lb></lb>that as thoſe who have treated of the <emph type="italics"></emph>Tor<lb></lb>ricellian<emph.end type="italics"></emph.end> Experiment, have for the moſt <lb></lb>part maintaind the Affirmative, or the Ne<lb></lb>gative of that famous Queſtion, Whether <lb></lb>or no that Noble Experiment infer a <emph type="italics"></emph>Va<lb></lb>cuum?<emph.end type="italics"></emph.end> ſo I ſhould on this occaſion inter<lb></lb>poſe my Opinion touching that Contro<lb></lb>verſie, or at leaſt declare whether or no, in <lb></lb>our Engine, the exſuction of the Air do <lb></lb>prove the place deſerted by the Air ſuck'd <lb></lb>out, to be truly empty, that is, devoid of <lb></lb>all Corporeal Subſtance. </s> <s>But beſides that, <lb></lb>I have neither the leiſure, nor the ability, <lb></lb>to enter into a ſolemn Debate of ſo nice a <lb></lb>Queſtion; Your Lordſhip may, if you <lb></lb>think it worth the trouble, in the Dia<lb></lb>logues not long ſince referr'd to, finde the <lb></lb>Difficulties on both ſides repreſented; <lb></lb>which then made me yield but a very wa<lb></lb>vering aſſent to either of the parties con<lb></lb>tending about the Queſtion: Nor dare I <lb></lb>yet take upon me to determine ſo difficult <lb></lb>a Controverſie. </s></p><pb xlink:href="013/01/150.jpg" pagenum="120"></pb><p type="main"> <s>For on the one ſide it appears, that not<lb></lb>withſtanding the exſuction of the Air, our <lb></lb>Receiver may not be deſtitute of all Bo<lb></lb>dies, ſince any thing placed in it, may be <lb></lb>ſeen there; which would not be, if it <lb></lb>were not pervious to thoſe Beams of <lb></lb>Light which rebounding from the ſeen <lb></lb>Object to our eyes, affect us with the ſenſe <lb></lb>of it: And that either theſe Beams are <lb></lb>Corporeal Emanations from ſome lucid <lb></lb>body, or elſe at leaſt the light they convey <lb></lb>doth reſult from the brisk Motion of ſome <lb></lb>ſubtle Matter, I could, if I miſtake not, <lb></lb>ſufficiently manifeſt out of the Dialogues <lb></lb>above-mention'd, if I thought your Lord<lb></lb>ſhip could ſeriouſly imagine that Light <lb></lb>could be convey'd without, at leaſt, having <lb></lb>(if I may ſo ſpeak) a Body for its Ve<lb></lb>hicle. </s></p><p type="main"> <s>By the ſixteenth Experiment, it alſo <lb></lb>appears that the cloſeneſs of our Receiver <lb></lb>hinders it not from admitting the Efflu<lb></lb>via of the Load-ſtone; which makes it <lb></lb>very probable that it alſo freely admits <lb></lb>the Magnetical ſteams of the Earth; con<lb></lb>cerning which, we have in another Trea<lb></lb>tiſe endeavour'd to manifeſt that numbers <lb></lb>of them do always permeate our Air. </s></p><p type="main"> <s>But on the other ſide it may be ſaid, <pb xlink:href="013/01/151.jpg" pagenum="121"></pb>That as for the ſubtle Matter which makes <lb></lb>the Objects encloſed in our evacuated Re<lb></lb>ceiver, viſible, and the Magnetical Efflu<lb></lb>via of the Earth that may be preſum'd to <lb></lb>paſs thorow it, though we ſhould grant <lb></lb>our Veſſel not to be quite devoyd of <lb></lb>them, yet we cannot ſo reaſonably affirm <lb></lb>it to be repleniſh'd with them, as we may <lb></lb>ſuppoſe, that if they were gather'd toge<lb></lb>ther into one place without Intervals be<lb></lb>tween them, they would fill but a ſmall <lb></lb>part of the whole Receiver. </s> <s>As in the <lb></lb>thirteenth Experiment, a piece of Match <lb></lb>was inconſiderable for its bulk, whileſt its <lb></lb>parts lay cloſe together, that afterwards <lb></lb>(when the Fire had ſcatter'd them into <lb></lb>ſmoke) ſeem'd to repleniſh all the Veſſel. <lb></lb></s> <s>For (as elſewhere our Experiments have <lb></lb>demonſtrated) both Light and the Efflu<lb></lb>via of the Load-ſtone, may be readily ad<lb></lb>mitted into a Glaſs, Hermetically ſeal'd, <lb></lb>though before their Admiſſion, as full of <lb></lb>Air as hollow Bodies here below are wont <lb></lb>to be, ſo that upon the exſuction of the <lb></lb>Air, the large ſpace deſerted by it, may <lb></lb>remain empty, notwithſtanding the pre<lb></lb>tence of thoſe ſubtle Corpuſcles, by <lb></lb>which Lucid and Magnetical Bodies pro<lb></lb>duce their effects. </s></p><pb xlink:href="013/01/152.jpg" pagenum="122"></pb><p type="main"> <s>And as for the Allegations above <lb></lb>mention'd, they ſeem to prove but that <lb></lb>the Receiver devoy'd of Air, <emph type="italics"></emph>May<emph.end type="italics"></emph.end> be re<lb></lb>pleniſh'd with ſome ſuch Etherial Matter, <lb></lb>as ſome Modern Naturaliſts write of; but <lb></lb>not that it really <emph type="italics"></emph>is<emph.end type="italics"></emph.end> ſo. </s> <s>And indeed to me <lb></lb>it yet ſeems, that as to thoſe ſpaces which <lb></lb>the <emph type="italics"></emph>Vacuiſts<emph.end type="italics"></emph.end> would have to be empty, be<lb></lb>cauſe they are manifeſtly devoid of Air; <lb></lb>and all groſſer Bodies, the <emph type="italics"></emph>Pleniſts<emph.end type="italics"></emph.end> (if I <lb></lb>may ſo call them) do not prove that ſuch <lb></lb>ſpaces are repleniſh'd with ſuch a ſubtle <lb></lb>Matter as they ſpeak of, by any ſenſible <lb></lb>effects, or operations of it (of which di<lb></lb>vers new Tryals purpoſely made, have not <lb></lb>yet ſhown me any) but onely conclude <lb></lb>that there muſt be ſuch a Body, becauſe <lb></lb>there cannot be a Void. </s> <s>And the reaſon <lb></lb>why there cannot be a Void, being by <lb></lb>them taken, not from any Experiments, <lb></lb>or <emph type="italics"></emph>Phænomena<emph.end type="italics"></emph.end> of Nature, that clearly and <lb></lb>particularly prove their <emph type="italics"></emph>Hypotheſis,<emph.end type="italics"></emph.end> but <lb></lb>from their notion of a Body, whoſe Na<lb></lb>ture, according to them, conſiſting one<lb></lb>ly in extenſion (which indeed ſeems the <lb></lb>property moſt eſſential to, becauſe inſepa<lb></lb>rable from a Body) to ſay a ſpace devoid <lb></lb>of Body, is to ſpeak in the School-mens <lb></lb>Phraſe, a Contradiction <emph type="italics"></emph>in Adjecto:<emph.end type="italics"></emph.end> This <pb xlink:href="013/01/153.jpg" pagenum="123"></pb>reaſon, I ſay, being thus deſum'd, ſeems <lb></lb>to make the Controverſie about a <emph type="italics"></emph>Vacu<lb></lb>um,<emph.end type="italics"></emph.end> rather a Metaphyſical, then a Phyſio<lb></lb>logical Queſtion; which therefore we ſhall <lb></lb>here no longer debate, finding it very dif<lb></lb>ficult either to ſatisfie Naturaliſts with <lb></lb>this Carteſian Notion of a Body, or to <lb></lb>manifeſt wherein it is erroneous, and ſub<lb></lb>ſtitute a better in its ſtead. </s></p><p type="main"> <s>But though we are unwilling to exa<lb></lb>mine any further the Inferences wont to <lb></lb>be made from the <emph type="italics"></emph>Torricellian<emph.end type="italics"></emph.end> Experi<lb></lb>ment, yet we think it not impertinent to <lb></lb>preſent Your Lordſhip with a couple of <lb></lb>Advertiſements concerning it. </s></p><p type="main"> <s>Firſt, then if in trying the Experiment <lb></lb>here or elſewhere, you make uſe of the <lb></lb>Engliſh meaſures that Mathematicians <lb></lb>and Tradeſmen are here wont to imploy, <lb></lb>You will, unleſs you be forewarn'd of it, <lb></lb>be apt to ſuſpect that thoſe that have writ<lb></lb>ten of the Experiment have been miſta<lb></lb>ken. </s> <s>For whereas men are wont gene<lb></lb>rally to talk of the Quick-ſilver's remain<lb></lb>ing ſuſpended at the heighth of between <lb></lb>ſix or ſeven and twenty Inches; we com<lb></lb>monly obſerv'd, when divers years ſince <lb></lb>we firſt were ſollicitous about this Expe<lb></lb>riment, that the Quick-ſilver in the Tube <pb xlink:href="013/01/154.jpg" pagenum="124"></pb>reſted at about 29 Inches & an half above <lb></lb>the ſurface of the Reſtagnant Quick-ſilver <lb></lb>in the Veſſel, which did at firſt both amaze <lb></lb>and perplex us, becauſe though we held it <lb></lb>not improbable that the difference of the <lb></lb>groſſer Engliſh Air, and that of <emph type="italics"></emph>Italy<emph.end type="italics"></emph.end> and <lb></lb><emph type="italics"></emph>France,<emph.end type="italics"></emph.end> might keep the Quick-ſilver from <lb></lb>falling quite as low in this colder, as in <lb></lb>thoſe warmer Climates; yet we could <lb></lb>not believe that that difference in the Air <lb></lb>ſhould alone be able to make ſo great a one <lb></lb>in the heights of the Mercurial Cylinders; <lb></lb>and accordingly upon enquiry we found, <lb></lb>that though the various denſity of the <lb></lb>Air be not to be over-look'd in this Ex<lb></lb>periment, yet the main Reaſon why we <lb></lb>found the Cylinder of Mercury to conſiſt <lb></lb>of ſo many Inches, was this, That our <lb></lb>Engliſh Inches are ſomewhat inferior in <lb></lb>length to the digits made uſe of in Fo<lb></lb>rein Parts, by the Writers of the Expe<lb></lb>riment. </s></p><p type="main"> <s>The next thing I deſire Your Lordſhip to <lb></lb>take notice of, is, That the heigth of the <lb></lb>Mercurial Cylinder is not wont to be <expan abbr="foũd">found</expan> <lb></lb>altogether ſo great as really it might <lb></lb>prove, by reaſon of the negligence or in<lb></lb>cogitancy of moſt that make the Experi<lb></lb>ment. </s> <s>For often times upon the opening <pb xlink:href="013/01/155.jpg" pagenum="125"></pb>of the inverted Tube into the Veſſell'd <lb></lb>Mercury, you may obſerve a bubble of <lb></lb>Air to aſcend from the bottom of the <lb></lb>Tube through the ſubſiding Quick-ſilver <lb></lb>to the top; and almoſt always you may, <lb></lb>if you look narrowly, take notice of a <lb></lb>multitude of ſmall bubbles all along the <lb></lb>inſide of the Tube betwixt the Quick<lb></lb>ſilver & the glaſs: (not now to mention the <lb></lb>Particles of Air that lye conceal'd in the <lb></lb>very Body of the Mercury) Many of <lb></lb>which, upon the Quick-ſilvers forſaking <lb></lb>the upper part of the Tube, do break in<lb></lb>to that deſerted ſpace where they finde <lb></lb>little or no reſiſtance to their expanding <lb></lb>of themſelves. </s> <s>Whether this be the rea<lb></lb>ſon that upon the Application of warm <lb></lb>Bodies to the emptyed part of the Tube, <lb></lb>the ſubjacent Mercury would be depreſſ'd <lb></lb>ſomewhat lower, we ſhall not determine; <lb></lb>though it ſeem very probable, eſpecially <lb></lb>ſince we found that upon the application <lb></lb>of Linnen cloaths dipped in Water, to <lb></lb>the ſame part of the Tube, the Quick<lb></lb>ſilver would ſomewhat aſcend, as if the <lb></lb>cold had condenſ'd the Impriſon'd Air, <lb></lb>that preſſ'd upon it, into a leſſer room. <lb></lb></s> <s>But that the deſerted ſpace is not wont to <lb></lb>be totally devoid of Air, we were induc'd <pb xlink:href="013/01/156.jpg" pagenum="126"></pb>to think by ſeveral Circumſtances. </s> <s>For <lb></lb>when an eminent Mathematician, and ex<lb></lb>cellent Experimenter, had taken great <lb></lb>pains and ſpent much time in accuratly fil<lb></lb>ling up a Tube of Mercury, we found <lb></lb>that yet there remain'd ſtore of inconſpi<lb></lb>cuous bubbles, by inverting the Tube, <lb></lb>letting the Quick-ſilver fall to its wonted <lb></lb>heighth; and by approaching (by de<lb></lb>grees) a red hot Iron to the out-ſide of the <lb></lb>Tube, over againſt the upper part of the <lb></lb>Mercurial Cylinder, for hereby the little <lb></lb>unheeded bubbles, being mightily expan<lb></lb>ded, aſcended in ſuch numbers, and ſo faſt <lb></lb>to the deſerted ſpace, that the upper part <lb></lb>of the Quick-ſilver ſeem'd, to our wonder, <lb></lb>to boyl. </s> <s>We further obſerv'd, That in <lb></lb>the tryals of the <emph type="italics"></emph>Torricellian<emph.end type="italics"></emph.end> Experiment <lb></lb>we have ſeen made by others, and (one <lb></lb>excepted) all our own, we never found that <lb></lb>upon the inclining of the Tube the Quick<lb></lb>ſilver would fully reach to the very top of <lb></lb>the ſeal'd end: which argued, that there <lb></lb>was ſome Air retreated thither that kept <lb></lb>the Mercury out of the unrepleniſh'd <lb></lb>ſpace. </s></p><p type="main"> <s>If Your Lordſhip ſhould now demand <lb></lb>what are the beſt expedients to hinder the <lb></lb>intruſion of the Air in this Experiment; <pb xlink:href="013/01/157.jpg" pagenum="127"></pb>we muſt anſwer, That of thoſe which are <lb></lb>eaſily intelligible without ocular demon<lb></lb>ſtration, we can at preſent ſuggeſt upon <lb></lb>our own tryals no better then theſe. </s> <s>Firſt, <lb></lb>at the open end of the Tube the Glaſs <lb></lb>muſt not onely be made as even at the ed<lb></lb>ges as you can, but it is very conveni<lb></lb>ent (eſpecially if the Tube be large) that <lb></lb>the bottom be every way bent inwards, <lb></lb>that ſo the Orifice, not much exceeding a <lb></lb>quarter of an Inch in Diameter, may be <lb></lb>the more eaſily and exactly ſtopp'd by the <lb></lb>Experimenter's finger; between which <lb></lb>and the Quick-ſilver, that there may be <lb></lb>no Air intercepted (as very often it hap<lb></lb>pens that there is) it is requiſite that the <lb></lb>Tube be fill'd as full as poſſibly it can be, <lb></lb>that the finger which is to ſtop it, preſſing <lb></lb>upon the accumulated and protuberant <lb></lb>Mercury, may rather throw down ſome, <lb></lb>then not finde enough exactly to keep out <lb></lb>the Air. </s> <s>It is alſo an uſeful and compen<lb></lb>dious way not to fill the Tube at firſt <lb></lb>quite ful of Mercury, but to leave near the <lb></lb>top about a qnarter of an Inch empty; for <lb></lb>if you then ſtop the open end with your <lb></lb>finger, and invert the Tube that quarter <lb></lb>of an Inch of Air will aſcend in a great <lb></lb>bubble to the top, and in its paſſage thi-<pb xlink:href="013/01/158.jpg" pagenum="128"></pb>ther, will gather up all the little bubbles, <lb></lb>and unite them with itſelf into one great <lb></lb>one, ſo that if by reinverting the Tube <lb></lb>you let that bubble return to the open <lb></lb>end of it, you will have a much cloſer Mer<lb></lb>curial Cylinder then before, and need but <lb></lb>to adde a very little Quick-ſilver more to <lb></lb>fill up the Tube exactly. </s> <s>And laſtly, as for <lb></lb>thoſe leſſer and inconſpicuous parcels of <lb></lb>Air which cannot this way be gleaned up, <lb></lb>You may endeavor before you invert the <lb></lb>Tube, to free the Quick-ſilver from them <lb></lb>by ſhaking the Tube, and gently knock<lb></lb>ing on the out-ſide of it, after every little <lb></lb>parcel of Quick-ſilver which you pour in; <lb></lb>and afterwards, by forcing the ſmall la<lb></lb>titant bubbles of Air to diſcloſe them<lb></lb>ſelves and break, by imploying a hot Iron <lb></lb>in ſuch manner as we lately mention'd. </s> <s>I <lb></lb>remember that by carefully filling the <lb></lb>Tube, though yet it were not quite free <lb></lb>from Air, we have made the Mercurial <lb></lb>Cylinder reach to 30 Inches and above an <lb></lb>eighth, and this in a very ſhort Tube: <lb></lb>which we therefore mention, becauſe we <lb></lb>have found, by experience, that in ſhort <lb></lb>Tubes a little Air is more prejudicial to <lb></lb>the Experiment then in long ones, where <lb></lb>the Air having more room to expand it <pb xlink:href="013/01/159.jpg" pagenum="129"></pb>ſelf, does leſs potently preſs upon the ſub<lb></lb>jacent Mercury. </s></p><p type="main"> <s>And ſince we are fallen upon the conſi<lb></lb>deration of the Altitude of the Mercurial <lb></lb>Cylinder, I muſt not conceal from Your <lb></lb>Lordſhip an Experiment relating thereun<lb></lb>to, which perhaps will ſet both You and <lb></lb>many of your Friends the <emph type="italics"></emph>Virtuoſi<emph.end type="italics"></emph.end> a think<lb></lb>ing; and, by diſcloſing ſome things a<lb></lb>bout the Air or Atmoſphere that have <lb></lb>ſcarce hitherto been taken notice of, may <lb></lb>afford you ſome hints conducive to a fur<lb></lb>ther diſcovery of the ſubject of this E<lb></lb>piſtle. </s></p><p type="main"> <s>WE took a Glaſs Tube, which, <lb></lb><arrow.to.target n="marg20"></arrow.to.target><lb></lb>though it were not much above <lb></lb>three Foot long, we made choice of be<lb></lb>cauſe it was of a more then ordinarily <lb></lb>even thickneſs. </s> <s>This we fill'd with Mer<lb></lb>cury, though not with as much care as we <lb></lb>could, yet with ſomewhat more then is <lb></lb>wont to be uſed in making the <emph type="italics"></emph>Torricellian<emph.end type="italics"></emph.end><lb></lb>Experiment. </s> <s>Then, having according to <lb></lb>the manner inverted the Tube, and open'd <lb></lb>the mouth of it beneath the ſurface of <lb></lb>ſome other Quick-ſilver, that in the Tube <lb></lb>fell down to the wonted heigth, leaving, <pb xlink:href="013/01/160.jpg" pagenum="130"></pb>as is uſual, ſome little Particles of Air in <lb></lb>the ſpace it deſerted, as we gheſt by ob<lb></lb>ſerving, that upon the Application of hot <lb></lb>Bodies to the upper part of the Tube, the <lb></lb>Quick-ſilver would be a little depreſſ'd. <lb></lb></s> <s>Laſtly, having put both the Tube and the <lb></lb>Veſſel it lean'd on into a convenient <lb></lb>Wooden Frame, to keep them from miſ<lb></lb>chances: we plac'd that Frame in a Win<lb></lb>dow within my Bed-chamber, that I might <lb></lb>both keep the Mercury from being ſtirr'd, <lb></lb>and have opportunity to watch from time <lb></lb>to time the <emph type="italics"></emph>Phænomena<emph.end type="italics"></emph.end> it was to exhibit. <lb></lb></s> <s>For the better diſcovery of which, when <lb></lb>the Quick-ſilver both in the Tube and <lb></lb>ſubjacent Veſſel was perfectly at reſt, we <lb></lb>took notice, by a mark made on the out<lb></lb>ſide of the Glaſs, how high the included <lb></lb>Liquor then reach'd. </s></p><p type="margin"> <s><margin.target id="marg20"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 18.</s></p><p type="main"> <s>During ſeveral Weeks that the Tube <lb></lb>was kept in that Window (which was very <lb></lb>rarely open'd) I had the opportunity to <lb></lb>obſerve, that the Quick-ſilver did ſome<lb></lb>times faintly imitate the Liquor of a <lb></lb>Weather-glaſs, ſubſiding a little in warm, <lb></lb>and riſing a little in cold Weather, which <lb></lb>we aſcribed to the greater or leſſer preſſure <lb></lb>of that little Air that remain'd at the top <lb></lb>of the Tube, expanded or condenſ'd by <pb xlink:href="013/01/161.jpg" pagenum="131"></pb>the heat or cold that affected the ambient <lb></lb>Air. </s> <s>But that which I was chiefly careful <lb></lb>to obſerve, was this, That oftentimes the <lb></lb>Quick-ſilver did riſe and fall in the Tube, <lb></lb>and that very notably, without conforming <lb></lb>it ſelf to what is uſual in Weather-glaſſes, <lb></lb>whoſe Air is at the top, nay quite contrary <lb></lb>thereunto: for ſometimes I obſerv'd it in <lb></lb>very cold weather (ſuch as this Winter has <lb></lb>already afforded us good ſtore of) to fall <lb></lb>down much lower then at other times, <lb></lb>when by reaſon of the abſence of both <lb></lb>Froſt, Snow, and ſharp Winds, the Air was <lb></lb>comparatively much warmer. </s> <s>And I fur<lb></lb>ther obſerv'd, That ſometimes the Quick<lb></lb>ſilver would for ſome days together reſt <lb></lb>almoſt at the ſame height; and at other <lb></lb>times again it would in the compaſs of the <lb></lb>ſame day conſiderably vary its altitude, <lb></lb>though there appear'd no change either in <lb></lb>the Air abroad, or in the temper of the Air <lb></lb>within the Room (wherein was conſtantly <lb></lb>kept a good Fire) nor in any thing elſe, to <lb></lb>which either I, or ſome eminently Learned <lb></lb>Men whom I then acquainted with the <lb></lb>Experiment, could reaſonably impute <lb></lb>ſuch a change: Eſpecially conſidering that <lb></lb>the ſpace wherein the Mercury wandred up <lb></lb>and down, within about five Weeks, a<lb></lb>mounted to full two Inches, of which we <pb xlink:href="013/01/162.jpg" pagenum="132"></pb>found by our ſeveral marks whereby we <lb></lb>had taken notice of its ſeveral removes, that <lb></lb>it had <expan abbr="deſcẽded">deſcended</expan> about (9/16) of an Inch from the <lb></lb>place where it firſt ſetled, & the other Inch <lb></lb>and (7/16) it had aſcended. </s> <s>And it ſeems pro<lb></lb>bable that the height of the Mercurial Cy<lb></lb>linder would have varied yet more, if the <lb></lb>Experiment had been made in the open <lb></lb>Air and in a long Tube, where the Parti<lb></lb>cles of the Impriſon'd Air, by having <lb></lb>more room to diſplay themſelves in, <lb></lb>might not have had ſo ſtrong a Spring to <lb></lb>work upon the Quick-ſilver with. </s> <s>But for <lb></lb>want both of time and of a competent <lb></lb>quantity of Mercury (which was not to be <lb></lb>procur'd where we then happen'd to be) <lb></lb>we were unable to make any further try<lb></lb>als: which therefore chiefly troubled us, <lb></lb>becauſe we would gladly have try'd an in<lb></lb>genious Experiment which was ſuggeſted <lb></lb>unto us by that excellent Mathematician <lb></lb>Mr. <emph type="italics"></emph>Wren,<emph.end type="italics"></emph.end> who being invited to name any <lb></lb>thing he would have us try touching the <lb></lb>preſſure of the Air, deſired us to obſerve <lb></lb>whether or no the Quick-ſilver in a long <lb></lb>Tube would not a little vary its height ac<lb></lb>cording to the Tides, eſpecially about the <lb></lb>New and Full Moon, about which times <lb></lb>Mariners obſerve thoſe great Flowings <lb></lb>and Ebbs of the Sea, that they call the <pb xlink:href="013/01/163.jpg" pagenum="133"></pb>Spring-Tides. </s> <s>For he ſagaciouſly and <lb></lb>plauſibly conjectur'd that ſuch obſervati<lb></lb>ons accurately made, would diſcover the <lb></lb>truth or erroneouſneſs of the <emph type="italics"></emph>Carteſian <lb></lb>Hypotheſis<emph.end type="italics"></emph.end> concerning the Ebbing and <lb></lb>Flowing of the Sea: which <emph type="italics"></emph>Des Cartes<emph.end type="italics"></emph.end><lb></lb>aſcribes to the greater preſſure made upon <lb></lb>the Air by the Moon, and the Intercur<lb></lb>rent Ethereal Subſtance at certain times <lb></lb>(of the Day, and of the Lunary Moneth) <lb></lb>then at others. </s> <s>But in regard we found <lb></lb>the Quick-ſilver in the Tube to move up <lb></lb>and down ſo uncertainly, by reaſon, as it <lb></lb>ſeems, of accidental mutation in the Air; <lb></lb>I ſomewhat doubt whether we ſhall finde <lb></lb>the Altitude of the Quick-ſilver to vary <lb></lb>as regularly as the Experiment is ingeni<lb></lb>ouſly propoſ'd. </s> <s>The ſucceſs we ſhall (God <lb></lb>permitting us to make tryal of it) acquaint <lb></lb>Your Lordſhip with; and in the mean <lb></lb>time take notice, that when we had occa<lb></lb>ſion to take the Tube out of the Frame <lb></lb>(after it had ſtaid there part of <emph type="italics"></emph>November<emph.end type="italics"></emph.end><lb></lb>and part of <emph type="italics"></emph>December<emph.end type="italics"></emph.end>) a good Fire being <lb></lb>then in the room, becauſe it was a Snowy <lb></lb>day, we found the Quick-ſilver in the <lb></lb>Tube to be above the upper ſurface of <lb></lb>the ſubjacent Mercury 29 Inches three <lb></lb>quarters. </s></p><pb xlink:href="013/01/164.jpg" pagenum="134"></pb><p type="main"> <s>If Your Lordſhip ſhould now ask me <lb></lb>what are the true cauſes of this varying al<lb></lb>titude of the Mercurial Cylinder; I ſhould <lb></lb>not undertake to anſwer ſo difficult a que<lb></lb>ſtion, and ſhould venter to ſay no more, <lb></lb>then that among divers poſſible cauſes to <lb></lb>which it may be aſcribed, it would not be, <lb></lb>perhaps, abſurd to reckon theſe that fol<lb></lb>low. </s></p><p type="main"> <s>Firſt then we may conſider, that the Air <lb></lb>in the upper part of the Tube is much <lb></lb>more rarified, and therefore more weak <lb></lb>then the external Air, as may appear by <lb></lb>this among other things, That upon the in<lb></lb>clining of the Tube the Quick-ſilver will <lb></lb>readily aſcend almoſt to the very top of <lb></lb>it, and ſo take up eight or nine tenth parts, <lb></lb>and perhaps more of that ſpace which it <lb></lb>deſerted before: which would not happen <lb></lb>if that whole ſpace had been full of unra<lb></lb>rified Air, ſince that (as tryal may eaſily <lb></lb>ſatisfie you) would not have ſuffer'd it <lb></lb>ſelf to be thruſt into ſo narrow a room by <lb></lb>ſo weak a preſſure. </s> <s>So that although in <lb></lb>our Tube when the included Air was <lb></lb>heated, the Quick-ſilver was ſomewhat <lb></lb>depreſſ'd: Yet there is this difference be<lb></lb>twixt ſuch a Tube and common Weather<lb></lb>Glaſſes, that in theſe the included and the <pb xlink:href="013/01/165.jpg" pagenum="135"></pb>ambient Air are in an <emph type="italics"></emph>Æquilibrium<emph.end type="italics"></emph.end> as to <lb></lb>preſſure, and the weight of the Water <lb></lb>that keeps them ſeparate is ſcarce conſi<lb></lb>derable. </s> <s>Whereas in ſuch a Tube as we <lb></lb>are ſpeaking of, the Air within is very <lb></lb>much more dilated then that without; and <lb></lb>'tis not ſo much the ſpring or reſiſtance <lb></lb>of the included Air, as the weight of the <lb></lb>Mercurial Cylinder it ſelf that hinders the <lb></lb>Quick-ſilver from aſcending higher; for <lb></lb>if we ſhould ſuppoſe that deſerted part of <lb></lb>the Tube perfectly devoid of Air, yet <lb></lb>would the Quick-ſilver riſe but a little <lb></lb>higher in it, and be far from filling it, in <lb></lb>regard the outward Air would not be <lb></lb>able to impel up ſuch a weight much <lb></lb>higher: whereas it may, by our former <lb></lb>Experiments appear, that if all the Air in <lb></lb>the upper part of a Weather-Glaſs were <lb></lb>away, the Water would be impell'd up to <lb></lb>the very top of it, though the Pipe were <lb></lb>above thirty Foot long. </s></p><p type="main"> <s>We may next conſider, that this ra<lb></lb>rified Air at the upper part of our Tube <lb></lb>being exactly ſhut up betwixt the Glaſs <lb></lb>and the Quick-ſilver, it was ſcarce ſubject <lb></lb>to any diſcernable alterations, ſave thoſe <lb></lb>it receiv'd from heat and cold. </s></p><pb xlink:href="013/01/166.jpg" pagenum="136"></pb><p type="main"> <s>And we may further conſider that yet <lb></lb>the external Air or Atmoſphere is ſubject <lb></lb>to many alterations, beſides them that <lb></lb>proceed from either of thoſe Quali<lb></lb>ties. </s></p><p type="main"> <s>For the Experiment that occaſion'd <lb></lb>this Diſcourſe, ſeems to make it proba<lb></lb>ble enough that there may be ſtrange <lb></lb>Ebbings and Flowings, as it were, in the <lb></lb>Atmoſphere; or at leaſt, that it may ad<lb></lb>mit great and ſudden Mutations, either as <lb></lb>to its Altitude or its Denſity, from cauſes, <lb></lb>as well unknown to us, as the effects are <lb></lb>unheeded by us. </s> <s>And that You may not <lb></lb>think that there is nothing in Nature but <lb></lb>our Experiment that agrees with this our <lb></lb>conjecture, we might put Your Lordſhip <lb></lb>in minde of the Pains and Aches that are <lb></lb>often complain'd of by thoſe that have <lb></lb>had great Wounds or Bruiſes, and that <lb></lb>doe preſage great Mutations in the Air <lb></lb>oftentimes, whilſt to ſtrong and healthy <lb></lb>Perſons no ſign of any ſuch thing appears. <lb></lb></s> <s>And that is alſo very memorable to this <lb></lb>purpoſe, which I remember I have ſome<lb></lb>where read in a Book of the Ingenious <lb></lb><emph type="italics"></emph>Kircherus,<emph.end type="italics"></emph.end> who giving a pertinent admoni<lb></lb>tion concerning the various refractions <lb></lb>that may happen in the Air, relates, That <pb xlink:href="013/01/167.jpg" pagenum="137"></pb>during his ſtay in <emph type="italics"></emph>Malta,<emph.end type="italics"></emph.end> he often ſaw <lb></lb>Mount <emph type="italics"></emph>Ætna,<emph.end type="italics"></emph.end> though the next day, not<lb></lb>withſtanding its being extreamly clear, he <lb></lb>could not ſee it; adding, that <emph type="italics"></emph>Vintemillius,<emph.end type="italics"></emph.end><lb></lb>a very Learned Perſon, did oftentimes, <lb></lb>from a Hill he names, behold the whole <lb></lb>Iſland he calls <emph type="italics"></emph>Luprica<emph.end type="italics"></emph.end> protuberant above <lb></lb>the Sea, though at other times, notwith<lb></lb>ſtanding a clear Sky, he could not ſee it. <lb></lb></s> <s>And though perhaps this may be in part a<lb></lb>ſcribed to the various light & poſition of <lb></lb>the ſun, or to the various diſpoſition of the <lb></lb>Spectators eye, or peradventure to ſome <lb></lb>other cauſe; yet the moſt probable cauſe <lb></lb>ſeems to be the differing Denſity of the <lb></lb>Air, occaſion'd by Exhalations capable to <lb></lb>increaſe the refraction, and conſequently <lb></lb>bring Beams to the Eye, which otherwiſe <lb></lb>would not fall on it. </s> <s>We have likewiſe <lb></lb>in another Treatiſe mention'd our having <lb></lb>often obſerv'd with Teleſcopes a plenty <lb></lb>of Steams in the Air, which without ſuch <lb></lb>a help would not be taken notice of, and <lb></lb>which as they were not at all times to be <lb></lb>ſeen even through a Teleſcope, ſo they <lb></lb>did ſometimes, eſpecially after a ſhower of <lb></lb>Rain, haſtily diſappear: and when we <lb></lb>have viſited thoſe places that abound with <lb></lb>Mines, we have ſeveral times been told <pb xlink:href="013/01/168.jpg" pagenum="138"></pb>by the Diggers, that even when the Sky <lb></lb>ſeem'd clear, there would not ſeldom ſud<lb></lb>denly ariſe, and ſometimes long continue, <lb></lb>a certain Steam (which they uſually call a <lb></lb>damp) ſo groſs and thick, that it would <lb></lb>oftentimes put out their very Candles, if <lb></lb>they did not ſeaſonably prevent it. </s> <s>And <lb></lb>I think it will eaſily be granted, that the <lb></lb>aſcenſion of ſuch Steams into this or that <lb></lb>part of the Air, and their mixing with it, <lb></lb>are very like to thicken it; as on the o<lb></lb>ther ſide either heat or the ſudden conden<lb></lb>ſation of the Air in another part of the At<lb></lb>moſphere (to mention now no other cau<lb></lb>ſes) are capable of rarifying it. </s></p><p type="main"> <s>Nor will it very much import the main <lb></lb>ſcope of our Diſcourſe, whether it be <lb></lb>ſuppoſ'd that the copious Steams the <lb></lb>earth ſends into the air, thicken that part <lb></lb>of the Atmoſphere that receives them, <lb></lb>and make it more heavy: Or that ſome<lb></lb>times the Fumes may aſcend with ſuch ce<lb></lb>lerity, that though the Air be thicken'd <lb></lb>yet they rather diminiſh then encreaſe its <lb></lb>gravitation, in regard that the quickneſs <lb></lb>of their aſcent, not onely keeps them <lb></lb>from gravitating themſelves, but may <lb></lb>hinder the preſſing downwards of many <lb></lb>Aërial Corpuſcles that they meet with in <pb xlink:href="013/01/169.jpg" pagenum="139"></pb>their way upwards. </s> <s>This, I ſay, is of <lb></lb>no great importance to our preſent Diſ<lb></lb>courſe, ſince either way the Terreſtrial <lb></lb>Steam may here and there conſiderably <lb></lb>alter the gravity or preſſure of the At<lb></lb>moſphere. </s></p><p type="main"> <s>Your Lordſhip may alſo be pleaſed to <lb></lb>remember, That by our ſeventeenth Ex<lb></lb>periment it appear'd that as when the Air <lb></lb>in the Receiver was expanded more then <lb></lb>ordinarily, the Quick-ſilver in the Tube <lb></lb>did proportionably ſubſide; ſo when the <lb></lb>Air in the ſame Receiver was a little more <lb></lb>then ordinarily compreſſ'd, it did impell <lb></lb>up the Quick-ſilver in the Tube above <lb></lb>the wonted height of betwixt ſix and ſe<lb></lb>ven and twenty digits. </s></p><p type="main"> <s>And if to theſe things we annex, that <lb></lb>for ought we can finde by tryals purpoſe<lb></lb>ly made, the degree of rarity or denſity <lb></lb>of the Air, ſhut up into our Receiver, does <lb></lb>not ſenſibly alter its temperature as to <lb></lb>cold or heat. </s> <s>It will not, I hope, appear <lb></lb>abſurd to conceive, That ſince the Air, <lb></lb>included in the Tube, could but very faint<lb></lb>ly hinder the aſcent of the Quick-ſilver, <lb></lb>or preſs it downwards, ſince too that inclu<lb></lb>ded Air could ſcarce immediately receive <lb></lb>any ſenſible alteration, ſave either by heat <pb xlink:href="013/01/170.jpg" pagenum="140"></pb>or cold. </s> <s>And ſince alſo that according to <lb></lb>the bare denſity or rarity of the Air in<lb></lb>cumbent on the ſubjacent Quick-ſilver in <lb></lb>the Veſſel, that in the Tube was impell'd <lb></lb>more or leſs high; ſuch changes happen<lb></lb>ing in the neighboring part of the out<lb></lb>ward Air, either by the aſcenſion of groſs <lb></lb>or copious exhalations, or by any other <lb></lb>cauſe (of which there may be divers) as <lb></lb>were capable to make conſiderable altera<lb></lb>tions in the conſiſtence of the Air, as to <lb></lb>rarity and denſity, <emph type="italics"></emph>may<emph.end type="italics"></emph.end> be able propor<lb></lb>tionably to alter the heighth of the <lb></lb>Quick-ſilver: I rather ſay, that ſuch alte<lb></lb>rations <emph type="italics"></emph>may<emph.end type="italics"></emph.end> be, then that they <emph type="italics"></emph>are<emph.end type="italics"></emph.end> the <lb></lb>cauſes of our <emph type="italics"></emph>Phænomenon,<emph.end type="italics"></emph.end> becauſe I think <lb></lb>it ſufficient, if I have propoſ'd conje<lb></lb>ctures not altogether irrational about a <lb></lb>new Myſtery of Nature, touching which, <lb></lb>the chief thing I pretend to, is to give oc<lb></lb>caſion to the Curious to inquire further <lb></lb>into it then I have been yet able to do. </s></p><p type="main"> <s>THe ſame Reaſon that mov'd us to <lb></lb><arrow.to.target n="marg21"></arrow.to.target><lb></lb>conclude, that by the drawing of the <lb></lb>Air out of the Receiver, the Mercury <lb></lb>would deſcend in a Tube ſhorter then ſix <lb></lb>and twenty digits, induc'd us alſo to ex-<pb xlink:href="013/01/171.jpg" pagenum="141"></pb>pect, that by the ſame means Water <lb></lb>might be brought to ſubſide in Glaſs <lb></lb>Tubes of a moderate length, though by <lb></lb>the noble Experiment, ſaid to have been <lb></lb>accurately made in <emph type="italics"></emph>France<emph.end type="italics"></emph.end> by <emph type="italics"></emph>Monſieur <lb></lb>Paſchal,<emph.end type="italics"></emph.end> we are informed that a Tube of <lb></lb>no leſs then about two and thirty Foot, <lb></lb>was found requiſite to make the Experi<lb></lb>ment <emph type="italics"></emph>De Vacuo<emph.end type="italics"></emph.end> ſucceed with Water in<lb></lb>ſtead of Quick-ſilver: ſo tall a Cylinder <lb></lb>of that lighter Liquor, being, it ſeems, <lb></lb>requiſite to equal the weight of a Mercu<lb></lb>rial Cylinder of ſix or ſeven and twenty <lb></lb>digits, and ſurmount the preſſure of the <lb></lb>Atmoſphere. </s></p><p type="margin"> <s><margin.target id="marg21"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 19.</s></p><p type="main"> <s>We took then a Tube of Glaſs, Her<lb></lb>metically ſeal'd at one end, of about four <lb></lb>foot in length, and not very ſlender: This <lb></lb>at the open end we fill'd with common <lb></lb>Water, and then ſtopt that end till we <lb></lb>had inverted the Tube, and open'd it be<lb></lb>neath the ſurface of a quantity of the like <lb></lb>Water, contain'd in a ſomewhat deep and <lb></lb>ſlender Veſſel. </s> <s>This Veſſel, with the <lb></lb>Tube in it, was let down into the Recei<lb></lb>ver, and the Receiver being cloſ'd up af<lb></lb>ter the accuſtom'd manner, the Pump was <lb></lb>ſet awork. </s></p><pb xlink:href="013/01/172.jpg" pagenum="142"></pb><p type="main"> <s>As much of the event as concerns our <lb></lb>preſent purpoſe, was this, That till a con<lb></lb>ſiderable part of the Air was drawn out <lb></lb>of the Receiver, the Tube continu'd top<lb></lb>full of Water as when it was put in, it be<lb></lb>ing requiſite that a great part of the Air <lb></lb>formerly contain'd in the Receiver, ſhould <lb></lb>be drawn out, to bring the remaining <lb></lb>Air to an <emph type="italics"></emph>Æquilibrium<emph.end type="italics"></emph.end> with ſo ſhort and <lb></lb>light a Cylinder of Water. </s> <s>But when <lb></lb>once the Water began to fall in the Tube, <lb></lb>then each exſuction of Air made it de<lb></lb>ſcend a little lower, though nothing near <lb></lb>ſo much as the Quick-ſilver at the begin<lb></lb>ning did in the Experiment formerly men<lb></lb>tion'd. </s> <s>Nor did there appear ſo much <lb></lb>inequality in the ſpaces tranſmitted by <lb></lb>the Water in its deſcent, as there did in <lb></lb>thoſe obſerv'd in the fall of the Quick<lb></lb>ſilver, of which the cauſe will ſcarce ſeem <lb></lb>abſtruſe to him that ſhall duly reflect up<lb></lb>on what has been already deliver'd. </s> <s>And <lb></lb>whereas we drew down the Quick-ſilver <lb></lb>in the Tube ſo far as to bring it within an <lb></lb>Inch of the ſurface of the other Quick<lb></lb>ſilver into which it was to fall; the loweſt <lb></lb>we were able to draw down the Water <lb></lb>was, by our conjecture, to about a Foot <pb xlink:href="013/01/173.jpg" pagenum="143"></pb>or more above the ſurface of that in the <lb></lb>Veſſel; of which I know not whether it <lb></lb>will be needful to aſſign ſo obvious a cauſe <lb></lb>as that, though the little Air remaining <lb></lb>in the Receiver could not hinder a Cylin<lb></lb>der of above an Inch high of Quick-ſilver <lb></lb>from ſubſiding; yet it might very well <lb></lb>be able, by its preſſure, to countervail the <lb></lb>weight of a Cylinder of a Foot long or <lb></lb>more, of a Liquor ſo much leſs ponderous <lb></lb>then Quick-ſilver, as Water is. </s> <s>And in <lb></lb>fine, to conclude our Experiment, when <lb></lb>the Water was drawn down thus low, we <lb></lb>found, that by letting in the outward Air, <lb></lb>it might be immediately impell'd up a<lb></lb>gain to the higher parts of the Tube. </s></p><p type="main"> <s>We will adde no more concerning this <lb></lb>Experiment, ſave that having try'd it in <lb></lb>one of our ſmall Receivers, we obſerv'd, <lb></lb>That upon the firſt exſuction of the Air <lb></lb>the Water did uſually ſubſide divers In<lb></lb>ches, and at the ſecond (exſuction) fall <lb></lb>down much lower, ſubſiding ſometimes <lb></lb>near two Foot; as alſo that upon the let<lb></lb>ting in of the Air from without, the Wa<lb></lb>ter was impell'd up with very great ce<lb></lb>lerity. </s></p><pb xlink:href="013/01/174.jpg" pagenum="144"></pb><p type="main"> <s>THat the Air has a notable Elaſtical <lb></lb><arrow.to.target n="marg22"></arrow.to.target><lb></lb>power (whenceſoever that proceeds) <lb></lb>we have, I ſuppoſe, abundantly evinc'd, <lb></lb>and it begins to be acknowledg'd by the <lb></lb>eminenteſt Modern Naturaliſts. </s> <s>But whe<lb></lb>ther or no there be in Water ſo much as <lb></lb>a languid one, ſeems hitherto to have been <lb></lb>ſcarce conſider'd, nor has been yet, for <lb></lb>ought I know, determin'd either way by <lb></lb>any Writer, which invited us to make the <lb></lb>following Experiment. </s></p><p type="margin"> <s><margin.target id="marg22"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 20.</s></p><p type="main"> <s>There was taken a great Glaſs-bubble, <lb></lb>with a long neck; (ſuch as Chymiſts are <lb></lb>wont to call a Philoſophical Egg) which <lb></lb>being fill'd with common Water till the <lb></lb>Liquor reach'd about a ſpan above the <lb></lb>bubble, and a piece of Paper being there <lb></lb>paſted on, was put unſtop'd into the Re<lb></lb>ceiver, and then the Air was ſuck'd out <lb></lb>after the wonted manner. </s> <s>The event was <lb></lb>this, That a conſiderable part of the Air, <lb></lb>pent up in the Receiver, was drawn out <lb></lb>before we diſcern'd any expanſion of the <lb></lb>Water; but, continuing the labor of <lb></lb>pumping, the Water manifeſtly began to <lb></lb>aſcend in the ſtem of the Glaſs, and di<lb></lb>vers bubbles looſening themſelves from <pb xlink:href="013/01/175.jpg" pagenum="145"></pb>the lower parts of the Veſſel, made their <lb></lb>way through the Body of the Water, to <lb></lb>the top of it, and there brake into the <lb></lb>Receiver: And after the Water once ap<lb></lb>pear'd to ſwell, then at each time the Stop<lb></lb>cock was turn'd to let out the air from the <lb></lb>Receiver into the Pump, the Water in the <lb></lb>Neck of the Glaſs did ſuddenly riſe a<lb></lb>bout the breadth of a Barly-corn in the <lb></lb>Neck of the Glaſs, and ſo attain'd, by <lb></lb>degrees, to a conſiderable height above <lb></lb>the mark formerly mention'd. </s> <s>And at <lb></lb>length (to make the expanſion of the Wa<lb></lb>ter more evident) the outward Air was <lb></lb>ſuddenly let in, and the Water immedi<lb></lb>ately ſubſided and deſerted all the ſpace it <lb></lb>had newly gain'd in the Glaſs. </s></p><p type="main"> <s>And, on this occaſion, it will not per<lb></lb>haps be amiſs to acquaint Your Lordſhip <lb></lb>here (though we have already mention'd <lb></lb>it in another Paper, to another purpoſe) <lb></lb>with another Expedient that we made uſe <lb></lb>of two or three years ago, to try whether <lb></lb>or no Water had a Spring in it. </s> <s>About <lb></lb>that time then, That Great and Learned <lb></lb>Promoter of Experimental Philoſophy <lb></lb>Dr. <emph type="italics"></emph>Wilkins,<emph.end type="italics"></emph.end> doing me the Honor to <lb></lb>come himſelf, and bring ſome of his in<lb></lb>quiſitive Friends to my Lodging, we <pb xlink:href="013/01/176.jpg" pagenum="146"></pb>there had in readineſs a round and hollow <lb></lb>Veſſel of Pewter, great enough to con<lb></lb>tain two pounds of Water, and exactly <lb></lb>cloſe every where, but at one little hole <lb></lb>where it was to be fill'd; then partly by <lb></lb>ſucking out the Air, and partly by inject<lb></lb>ing Water with a Syringe, it was (not <lb></lb>without ſome difficulty) fill'd up to the <lb></lb>top; and that hole being plac'd directly <lb></lb>upwards, there was a little more Water <lb></lb>leiſurely forc'd in by the Syringe. </s> <s>Upon <lb></lb>which, though the Veſſel were permitted <lb></lb>to reſt, and the hole kept in its former po<lb></lb>ſture, yet the compreſſ'd Water leiſurely <lb></lb>ſwell'd above the Orifice of the hole, and <lb></lb>divers drops ran over along the ſides of the <lb></lb>Veſſel. </s> <s>After this, we cauſ'd a skilful Pew<lb></lb>terer (who had made the Globe) to cloſe <lb></lb>it up in our preſence with Soder ſo exqui<lb></lb>ſitely, that none ſuſpected there was any <lb></lb>thing left in it beſides Water. </s> <s>And laſt<lb></lb>ly, the Veſſel thus ſoder'd up, was wari<lb></lb>ly and often ſtruck in divers places with a <lb></lb>Wooden Mallet, and thereby was mani<lb></lb>feſtly compreſſ d, whereby the incloſed <lb></lb>Water was crouded into leſs room then it <lb></lb>had before: And thereupon when we took <lb></lb>a Needle, and with it and the Mallet per<lb></lb>forated the Veſſel, and drew out the <pb xlink:href="013/01/177.jpg" pagenum="147"></pb>Needle again; the Water (but in a very <lb></lb>ſlender Stream) was ſuddenly thrown af<lb></lb>ter it into the Air, to the height of two <lb></lb>or three Feet. </s> <s>As for the other <emph type="italics"></emph>Phænome<lb></lb>na<emph.end type="italics"></emph.end> of this Experiment, ſince they belong <lb></lb>not to our preſent purpoſe, and are partly <lb></lb>mention'd in another of our Papers, we <lb></lb>ſhall, inſtead of recording them here, give <lb></lb>this Advertiſement: That as evidently <lb></lb>as this Experiment, and that made in our <lb></lb>Receiver, ſeem to prove a power in the <lb></lb>Water to expand and reſtore it ſelf after <lb></lb>compreſſion; yet for a reaſon to be met <lb></lb>with ere long, I judged it not ſafe to in<lb></lb>fer that Concluſion from theſe Premiſes, <lb></lb>till I had made ſome of the following try<lb></lb>als, to the mention of which I will there<lb></lb>fore haſten. </s></p><p type="main"> <s>TO diſcover whether the Expanſion <lb></lb><arrow.to.target n="marg23"></arrow.to.target><lb></lb>of the Water really proceeded <lb></lb>from an Elaſtical power in the parts of <lb></lb>the Water it ſelf, we thought it requiſite <lb></lb>to try two things: The one, Whether or no <lb></lb>the Atmoſphere gravitates upon Bodies <lb></lb>under Water; and the other, Whether <lb></lb>in caſe it do gravitate, the Intumeſcence <lb></lb>of the Water may not be aſcribed to ſome <pb xlink:href="013/01/178.jpg" pagenum="148"></pb>ſubſtance ſubtler then it ſelf, reſiding m<lb></lb>it. </s> <s>In order to the ſatisfying my ſelf about <lb></lb>the firſt of theſe, I intended to let down <lb></lb>into the Receiver a Veſſel of Water, <lb></lb>wherein ſhould be immerſ'd a very ſmall <lb></lb>oyl'd Bladder, almoſt devoid of Air, but <lb></lb>ſtrongly ty'd up at the Neck with a ſtring, <lb></lb>and detain'd a little under Water by ſuch <lb></lb>a weight faſten'd to that ſtring, as ſhould <lb></lb>juſt be able to keep the Bladder from <lb></lb>ſwimming, and no more. </s> <s>For I ſuppoſ'd, <lb></lb>that if when all things were thus order'd, <lb></lb>the Receiver were empty'd, in caſe there <lb></lb>were any ſuch preſſure of the Atmoſphere <lb></lb>upon Water, as I was inclin'd to believe, <lb></lb>the Air within the Bladder, being upon the <lb></lb>exſuction of the Air within the Receiver, <lb></lb>freed from that preſſure, and being preſſ'd <lb></lb>onely by the ſmall weight of the in<lb></lb>cumbent Water, would conſiderably ex<lb></lb>pand it ſelf; but whil'ſt we were prepa<lb></lb>ring Bladders for this Experiment, there <lb></lb>occurr'd an eaſie way for the making at <lb></lb>once both the Diſcoveries I deſir'd. </s></p><p type="margin"> <s><margin.target id="marg23"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 21.</s></p><p type="main"> <s>We took then a Glaſs Viol, containing <lb></lb>by gheſs a pound and ſome ounces of <lb></lb>Water, this we fill'd top full, and then <lb></lb>we put into the Neck of it a Glaſs Pipe <lb></lb>a pretty deal bigger then a Gooſe Quill, <pb xlink:href="013/01/179.jpg" pagenum="149"></pb>open at both ends, and of divers Inches <lb></lb>in length: One end of this Pipe was ſo <lb></lb>put into the Neck of the Viol, as to reach <lb></lb>a little below it, and then was carefully <lb></lb>cemented thereto that no Air might get <lb></lb>into the Viol, nor no Water get out of <lb></lb>it, otherwiſe then through the Pipe; and <lb></lb>then the Pipe being warily fill'd, about <lb></lb>half way up to the top, with more Wa<lb></lb>ter, and a mark being paſted over againſt <lb></lb>the upper ſurface of the Liquor; the Viol <lb></lb>thus fitted with the Pipe, was, by ſtrings <lb></lb>let down into the Receiver, and according <lb></lb>to the wonted manner exquiſitely cloſ'd <lb></lb>up in it. </s></p><p type="main"> <s>This done, we began to Pump out the <lb></lb>Air, and when a pretty quantity of it had <lb></lb>been drawn away, the Water in the Pipe <lb></lb>began to riſe higher in the Pipe, at the <lb></lb>ſides of which ſome little bubbles diſco<lb></lb>ver'd themſelves. </s> <s>After a little while <lb></lb>longer, the Water ſtill ſwelling, there <lb></lb>appear'd at the bottom of the Pipe a bub<lb></lb>ble about the bigneſs of a ſmall Pea, <lb></lb>which aſcending through the Pipe to the <lb></lb>top of the Water, ſtaid there awhile and <lb></lb>then broke; but the Pump being nimbly <lb></lb>ply'd, the expanſion of the Water ſo en<lb></lb>creaſ'd, that quickly, getting up to the <pb xlink:href="013/01/180.jpg" pagenum="150"></pb>top of the Pipe ſome drops of it be<lb></lb>gan to run down along the out-ſide of it, <lb></lb>which oblig'd us to forbear pumping a<lb></lb>while, and give the Water leave to ſub<lb></lb>ſide within leſs then two Inches of the <lb></lb>bottom of the Pipe. </s> <s>After this the <lb></lb>Pump being again ſet at work, the bub<lb></lb>bles began to aſcend from the bottom <lb></lb>of the Pipe, being not all of a ſize, but yet <lb></lb>ſo big, that eſtimating one with another, <lb></lb>they appear'd to be of the ſize of the ſmal<lb></lb>ler ſort of Peas; and of theſe we reckon'd <lb></lb>about ſixty which came up one after ano<lb></lb>ther, beſides ſtore of ſmaller ones, of which <lb></lb>we made no reckoning: And at length, <lb></lb>growing weary of reckoning and pumping <lb></lb>too (becauſe we found, that in ſpight <lb></lb>of all our pains and induſtry, ſome un<lb></lb>diſcern'd Leak or other in the Recei<lb></lb>ver hinder'd us from being able to empty <lb></lb>it altogether) we thought fit to deſiſt for <lb></lb>that time. </s> <s>After tryal made of what o<lb></lb>peration the external Air, being let in <lb></lb>upon the expanded Water, would have; <lb></lb>and accordingly turning the Key to let in <lb></lb>the Air, we ſaw, as we expected, that <lb></lb>the Water in the Pipe in a moment fell <lb></lb>down almoſt to the bottom of it. </s></p><pb xlink:href="013/01/181.jpg" pagenum="151"></pb><p type="main"> <s>Now of this Experiment there are two <lb></lb>or three Circumſtances yet to be men<lb></lb>tion'd, which are no leſs then thoſe alrea<lb></lb>dy recited, pertinent to our preſent pur<lb></lb>poſe. </s></p><p type="main"> <s>In the firſt place then, when the great<lb></lb>er part of the Air had been pump'd out of <lb></lb>the Receiver, the riſing bubbles aſcend<lb></lb>ed ſo very ſlowly in the Pipe, that their <lb></lb>Progreſs was ſcarce diſcernable; which <lb></lb>ſeem'd to proceed from this, That their <lb></lb>bigneſs was ſuch, That they could not <lb></lb>ſufficiently extend themſelves in the <lb></lb>cavity of the Glaſs, without preſſing <lb></lb>on both hands againſt the ſides of it, <lb></lb>whereby they became of more difficult <lb></lb>extruſion to the Water. </s> <s>And though it <lb></lb>may ſeem ſtrange theſe bubbles ſhould <lb></lb>be of any conſiderable bulk, ſince 'tis <lb></lb>like they conſiſted of leſſer parcels of <lb></lb>the Air lurking in the Water, then thoſe <lb></lb>that were vigorous enough to make their <lb></lb>way through long before them: yet they <lb></lb>were commonly much larger then before, <lb></lb>ſome of them being equal in quantity to <lb></lb>four or five Peas: Whether this their in<lb></lb>creaſe of bulk proceeded from the greater <lb></lb>decrement of the preſſure of the Air, <pb xlink:href="013/01/182.jpg" pagenum="152"></pb>or from the Union of two or three of <lb></lb>thoſe numerous bubbles which were then <lb></lb>generated below the bottom of the Pipe, <lb></lb>where we could not ſee what was done a<lb></lb>mong them. </s></p><p type="main"> <s>Another thing we noted in our bubbles <lb></lb>was, That whereas in ordinary ones the <lb></lb>Air, together with the thin film of Water <lb></lb>that inveſts and detains, is wont to ſwell <lb></lb>above the ſurface of the Water it ſwims <lb></lb>on, and commonly to conſtitute Hemiſ<lb></lb>pherical Bodies with it, the little parcels <lb></lb>of Air that came up after the Receiver <lb></lb>was pretty well empty'd, did not make <lb></lb>protuberant bubbles, but ſuch whoſe up<lb></lb>per ſurface was either level with or be<lb></lb>neath that of the Water, ſo that the up<lb></lb>per ſurface being uſually ſomewhat con<lb></lb>vex, the leſs protuberant parts of it had <lb></lb>a pretty quantity of Water remaining a<lb></lb>bove them. </s></p><p type="main"> <s>We alſo further obſerv'd, That where<lb></lb>as in the bubbles that firſt appear'd in <lb></lb>the Pipe, the aſcending Air did, as in o<lb></lb>ther common bubbles, make its way up<lb></lb>wards, by dividing the Water through <lb></lb>which it paſſ'd, in thoſe bubbles that ap<lb></lb>pear'd at the latter end of our Experi<lb></lb>ment, when the preſſure of the little ex-<pb xlink:href="013/01/183.jpg" pagenum="153"></pb>ternal Air, remaining in the Receiver, <lb></lb>was grown inconſiderable, the aſcending <lb></lb>parcels of Air having now little more <lb></lb>then the weight of the incumbent Water <lb></lb>to ſurmount, were able both ſo to expand <lb></lb>themſelves as to fill up that part of the <lb></lb>Pipe which they pervaded, & by preſſing <lb></lb>every way againſt the ſides of it, to lift <lb></lb>upwards with them what Water they <lb></lb>found above them, without letting any <lb></lb>conſiderable quantity glide down along <lb></lb>the ſides of the Glaſs: So that ſometimes <lb></lb>we could ſee a bubble thruſt on before it <lb></lb>a whole Cylinder of Water of perhaps <lb></lb>an Inch high, and carry it up to the top <lb></lb>of the Pipe; though as we formerly no<lb></lb>ted, upon the letting in the external Air, <lb></lb>theſe tumid bubbles ſuddenly relapſ'd to <lb></lb>their former inconſpicuouſneſs. </s></p><p type="main"> <s>All theſe things laid together ſeem'd <lb></lb>ſufficiently to confirm that, which the <lb></lb>conſideration of the thing it ſelf would <lb></lb>eaſily enough perſwade, namely, That <lb></lb>the Air, and ſuch like Bodies being under <lb></lb>Water, may be preſſ'd upon as well by <lb></lb>the Atmoſphere, as by the weight of the <lb></lb>incumbent Water it ſelf. </s></p><p type="main"> <s>Hence likewiſe we may verifie what we <lb></lb>obſerv'd at the cloſe of the foregoing <pb xlink:href="013/01/184.jpg" pagenum="154"></pb>Experiment, namely, That from the ſole <lb></lb>ſwelling of Water there recorded, it can<lb></lb>not be ſo ſafely concluded that Water, <lb></lb>when freed from compreſſion, is endowd <lb></lb>with an Elaſtical power of expanding it <lb></lb>ſelf, ſince thereby it appears that the In<lb></lb>tumeſcence produc'd by that Experiment, <lb></lb>may (at leaſt in great part) be aſcrib'd to <lb></lb>the numerous little bubbles which are <lb></lb>wont to be produc'd in Water, from <lb></lb>which the preſſure of the Atmoſphere is <lb></lb>in great meaſure taken off. </s> <s>So apt are we <lb></lb>to be miſ-led, even by Experiments them<lb></lb>ſelves, into Miſtakes, when either we con<lb></lb>ſider not that moſt Effects may proceed <lb></lb>from various Cauſes, or minde onely thoſe <lb></lb>Circumſtances of our Experiment, which <lb></lb>ſeem to comply with our preconceiv'd <lb></lb><emph type="italics"></emph>Hypotheſis<emph.end type="italics"></emph.end> or Conjectures. </s></p><p type="main"> <s>And hence it ſeems alſo probable, that <lb></lb>in the Pores or inviſible little receſſes of <lb></lb>Water it ſelf there lie commonly inter<lb></lb>ſperſ'd many parcels of either Air, or at <lb></lb>leaſt ſomething Analogous thereunto, al<lb></lb>though ſo very ſmall that they have not <lb></lb>been hitherto ſo much as ſuſpected to <lb></lb>lurk there. </s> <s>But if it be demanded how it <lb></lb>appears that there is interſperſ'd through <lb></lb>the Body of Water any ſubſtance thinner <pb xlink:href="013/01/185.jpg" pagenum="155"></pb>then it ſelf, and why that which produc'd <lb></lb>the bubbles above mention'd ſhould not <lb></lb>be reſolutely ſaid to be nothing elſe then <lb></lb>a more active and ſpirituous part of the <lb></lb>Water, we ſhall, in order to the Elucida<lb></lb>tion of this matter, ſubjoyn to what <lb></lb>was formerly deliver'd the following Ex<lb></lb>periment. </s></p><p type="main"> <s>WE recited in our nineteenth Ex<lb></lb>periment, how by drawing moſt <lb></lb><arrow.to.target n="marg24"></arrow.to.target><lb></lb>of the Air out of the Receiver, we made <lb></lb>the Water ſubſide by degrees in a Glaſs <lb></lb>not four Foot long: We ſhall now adde, <lb></lb>that in the like Experiment made in ſuch <lb></lb>a Tube, or a greater, it may be obſerv'd, <lb></lb>That when the Water begins to fall, there <lb></lb>will appear ſtore of bubbles faſten'd all a<lb></lb>long to the ſides of the Glaſs; of which <lb></lb>bubbles, by the agitation of the Veſſel <lb></lb>conſequent upon pumping, there will ariſe <lb></lb>good numbers to the top of the Water, <lb></lb>and there break; and as the Cylinder of <lb></lb>Water is brought to be lower and lower, <lb></lb>ſo the bubbles will appear more numerous <lb></lb>in that part of the Tube which the Water <lb></lb>yet fills; and the nearer the ſurface of the <lb></lb>Water, in its deſcent, approaches to theſe <pb xlink:href="013/01/186.jpg" pagenum="156"></pb>bubbles, the greater they will grow, be<lb></lb>cauſe having the leſs weight and preſſure <lb></lb>upon them, the Expanſion of that Air <lb></lb>which makes them, can be the leſs reſiſted <lb></lb>by the preſſure of the incumbent Water <lb></lb>and Air; as ſeems probable from hence, <lb></lb>that upon the letting in a little external <lb></lb>Air, thoſe bubbles immediately ſhrink. </s></p><p type="margin"> <s><margin.target id="marg24"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 22.</s></p><p type="main"> <s>It may indeed, as we lately intimated, <lb></lb>be conjectur'd, that theſe bubbles pro<lb></lb>ceed not ſo much from any Air pre-exi<lb></lb>ſtent in the Water, and lurking in the <lb></lb>Pores of it, as from the more ſubtle parts <lb></lb>of the Water it ſelf; which by the expan<lb></lb>ſion allow'd them upon the diminiſh'd <lb></lb>preſſure of the ambient Bodies may gene<lb></lb>rate ſuch bubbles. </s> <s>And indeed, I am not <lb></lb>yet ſo well ſatisfied that bubbles may not <lb></lb>(at leaſt ſometimes) have ſuch an Origina<lb></lb>tion: but that which makes me ſuſpect <lb></lb>that thoſe in our tryals contain'd real Air <lb></lb>formerly latitant in the Pores of the Wa<lb></lb>ter, is this, That upon the inletting of <lb></lb>the external Air, the Water was not <lb></lb>again impell'd to the very top of the <lb></lb>Tube whence it began to fall, but was <lb></lb>ſtopt in its aſcent near an Inch beneath <lb></lb>the top. </s> <s>And ſince, if the upper part of <lb></lb>the Tube had been devoyd of any other <pb xlink:href="013/01/187.jpg" pagenum="157"></pb>then ſuch Ethereal matter as was ſubtle <lb></lb>enough freely to penetrate the pores of <lb></lb>the Glaſs, the external Air would have <lb></lb>been able to impel the Water to the top <lb></lb>of a Tube ſeven or eight times as long as <lb></lb>ours was; The <emph type="italics"></emph>Phænomenon<emph.end type="italics"></emph.end> under conſi<lb></lb>deration ſeem'd manifeſtly to argue that <lb></lb>the many bubbles that broke at the top <lb></lb>of the Water did contain a real Air, <lb></lb>which, being collected into one place and <lb></lb>hinder'd by the top of the Glaſs from re<lb></lb>ceding, was able to withſtand the preſſure <lb></lb>of the outward Air. </s> <s>As we ſee that if <lb></lb>never ſo little Air remain in the Tube up<lb></lb>on the making the Experiment <emph type="italics"></emph>De Vacuo<emph.end type="italics"></emph.end><lb></lb>with Quick-ſilver, no inclining of the <lb></lb>Tube, though a long one, will enable a <lb></lb>Man to impel the Mercury up to the very <lb></lb>top, by reaſon (as we formerly noted) <lb></lb>of the reſiſtance of the included Air, which <lb></lb>will not be compreſſ'd beyond a certain <lb></lb>degree. </s></p><p type="main"> <s>But in order to a further Diſcovery what <lb></lb>our bubbles were, we will, on this occa<lb></lb>ſion, inform Your Lordſhip that we try'd <lb></lb>the XIX<emph type="sup"></emph>th<emph.end type="sup"></emph.end> <emph type="italics"></emph>Experiment<emph.end type="italics"></emph.end> in one of our ſmall <lb></lb>Receivers, and ſound, that upon the draw<lb></lb>ing down of the Water, ſo many bubbles <lb></lb>diſcloſ'd themſelves and broke into the <pb xlink:href="013/01/188.jpg" pagenum="158"></pb>upper part of the Tube, that having after<lb></lb>wards let in the external Air, the Water <lb></lb>was not thereby impell'd to the top of the <lb></lb>Tube (three Foot in length) within a lit<lb></lb>tle more then half an Inch. </s> <s>And whe<lb></lb>ther or no it were Air that poſſeſſ'd that <lb></lb>ſpace at the top of the Tube which was <lb></lb>not fill'd with Water, we took this courſe <lb></lb>to examine. </s> <s>We drew the ſecond time <lb></lb>the Air out of the Receiver, and found, <lb></lb>that by reaſon of the body that poſſeſſ'd <lb></lb>the top of the Tube, we were able not <lb></lb>onely to make the Water in the Tube fall <lb></lb>to a level with the ſurface of the Water <lb></lb>in the Veſſel: But alſo (by plying the <lb></lb>Pump a little longer) a great way beneath <lb></lb>it: which ſince it could not well be aſcrib'd <lb></lb>to the bare ſubſiding of the Water by rea<lb></lb>ſon of its own weight, argued that the Wa<lb></lb>ter was depreſſ'd by the Air: which was <lb></lb>confirm'd by the Figure of the ſurface of <lb></lb>the Water in the Tube, which was much <lb></lb>more concave then that of Water in <lb></lb>Tubes of that bigneſs uſes to be. </s> <s>And <lb></lb>this further tryal (to adde that upon <lb></lb>the by) we made at the ſame time, That <lb></lb>when the Water in the Pipe was drawn <lb></lb>down almoſt as low as the Water without <lb></lb>it, we obſerv'd, that (though we deſiſted <pb xlink:href="013/01/189.jpg" pagenum="159"></pb>from pumping) by the bare application <lb></lb>of a hand moderately warm to the deſert<lb></lb>ed part of the Tube, the remaining Wa<lb></lb>ter would be ſpeedily and notably de<lb></lb>preſſ'd. </s> <s>And having for a while held a <lb></lb>kindled Coal to the outſide of the Tube, <lb></lb>(the Pump being ſtill unimploy'd, becauſe <lb></lb>the Veſſel chanced to hold extraordinarily <lb></lb>well) the Air was by the heat ſo far ex<lb></lb>panded, that it quickly drave the Water <lb></lb>to the bottom of the Tube, which was <lb></lb>divers Inches beneath the ſurface of the <lb></lb>ambient Water. </s> <s>Whereby it appears (by <lb></lb>the ſame way by which we formerly mea<lb></lb>ſur'd the dilatation of the Air) that the <lb></lb>Air, even when it is expanded to between <lb></lb>90 and 100 times, its extent will yet rea<lb></lb>dily admit of a much further rarifaction <lb></lb>by heat. </s></p><p type="main"> <s>I conſider'd alſo that in caſe the Bub<lb></lb>bles we have been ſpeaking of, were pro<lb></lb>duc'd by the parcels of Air latitant in the <lb></lb>Water, that Air being now got together <lb></lb>to the top of the Tube, though the Air <lb></lb>were again drawn out of the Receiver, <lb></lb>the taking off its preſſure would not diſ<lb></lb>cloſe bubbles as before; and accordingly, <lb></lb>the Air being again pump'd out, the Wa<lb></lb>ter in the Tube deſcended as formerly: <pb xlink:href="013/01/190.jpg" pagenum="160"></pb>but for a great while we ſcarce ſaw one <lb></lb>bubble appear, onely when the Receiver <lb></lb>had been very much exhauſted, and the <lb></lb>Water was fallen very low, there appear'd <lb></lb>near the bottom of the Tube, certain <lb></lb>little bubbles, which ſeem'd to conſiſt of <lb></lb>ſuch parcels of Air as had not, by reaſon <lb></lb>of their ſmalneſs, got up to the top of <lb></lb>the Water, with the more bulkie and vi<lb></lb>gorous ones. </s> <s>And that which is not in<lb></lb>conſiderable, is, That having, by letting <lb></lb>in the Air, forc'd up the Water into the <lb></lb>Tube, we could not perceive that it aſ<lb></lb>cended nearer the top, though we per<lb></lb>mitted the Engine to remain unimploy'd <lb></lb>for two or three Nights together, and <lb></lb>watch'd whether the Water would ſwell <lb></lb>up and fill the Tube. </s> <s>And on this occa<lb></lb>ſion I remember, that having try'd ſuch an <lb></lb>Experiment as this with Quick-ſilver in<lb></lb>ſtead of Water, in a Tube of about a Foot <lb></lb>and a half long, wherein it might ſeem <lb></lb>more hopeful to eſcape bubbles; yet up<lb></lb>on the drawing down the Quick-ſilver as <lb></lb>low as we could, and letting in the exter<lb></lb>nal Air upon it, we found that ſome lurk<lb></lb>ing particles of Air were got up to the top <lb></lb>of the Tube, and hinder'd the Quick<lb></lb>ſilver from being forc'd up again ſo high. <pb xlink:href="013/01/191.jpg" pagenum="161"></pb>And though the Quick-ſilver were by <lb></lb>this means brought to appear a very cloſe <lb></lb>and lovely Metalline Cylinder, not inter<lb></lb>rupted by interſperſ'd bubbles as before; <lb></lb>yet having cauſ'd the Air to be again <lb></lb>drawn out of the Receiver, I could per<lb></lb>ceive ſeveral little bubbles to diſcloſe <lb></lb>themſelves, faſten'd to the inſide of the <lb></lb>Tube, near the bottom of it; and having <lb></lb>purpoſely watch'd one or two of the chief<lb></lb>eſt, I had the pleaſure to obſerve, that <lb></lb>though they grew bigger and bigger as <lb></lb>the ſurface of the Mercurial Cylinder fell <lb></lb>nearer and nearer to them, ſo as that at <lb></lb>length they ſwell'd into a conſpicuous <lb></lb>bulk; yet upon the wary letting in the <lb></lb>Air upon them, they did not break, but <lb></lb>preſently ſhrunk up into a littleneſs that <lb></lb>render'd them inconſpicuous. </s></p><p type="main"> <s>Whence it ſeems very probable, if not <lb></lb>certain, that even in the cloſeſt and moſt <lb></lb>ponderous Liquors, and therefore much <lb></lb>more in Water, there may lurk undiſcern<lb></lb>able parcels of Air, capable, upon the <lb></lb>removal of the preſſure of the ambient <lb></lb>Air (though but in part) and that of the <lb></lb>Liquor wherein it lurks, to produce con<lb></lb>ſpicuous bubbles. </s> <s>And conſequently, if <lb></lb>it ſeem inconvenient to admit an Elaſtical <pb xlink:href="013/01/192.jpg" pagenum="162"></pb>power in the Water, it may be ſaid that <lb></lb>the ſwelling of the compreſſ'd Water in <lb></lb>the Pewter Veſſel lately mention'd, and <lb></lb>the ſpringing up of the Water at the hole <lb></lb>made by the Needle, were not the effects <lb></lb>of any internal <emph type="italics"></emph>Elater<emph.end type="italics"></emph.end> of the Water, but <lb></lb>of the ſpring of the many little particles <lb></lb>of Air diſperſ'd through that Water, and <lb></lb>acting upon it in their ſudden recovering <lb></lb>themſelves to a greater extent, then that <lb></lb>to which a violent compreſſion had re<lb></lb>duc'd them. </s></p><p type="main"> <s>But though, from all theſe particulars, <lb></lb>it ſeems manifeſt that the bubbles we have <lb></lb>been all this while treating of, were pro<lb></lb>duc'd by ſuch a ſubſtance as may be pro<lb></lb>perly enough call'd Air; yet till we ſhall <lb></lb>have had the opportunity of making <lb></lb>ſome further tryals concerning the nature <lb></lb>of the Air, we ſhall not reſolutely deter<lb></lb>mine whether or no Air be a Primogenial <lb></lb>Body (if I may ſo ſpeak) that cannot <lb></lb>now be generated or turn'd either into <lb></lb>Water or any other Body. </s> <s>Yet in the <lb></lb>mean while (becauſe it is an important <lb></lb>Queſtion, and if rightly determin'd, may <lb></lb>much conduce to the knowledge of the <pb xlink:href="013/01/193.jpg" pagenum="163"></pb>nature of the Air) We think it not unfit <lb></lb>to make a brief mention of ſome of the <lb></lb>particulars which at preſent occur to our <lb></lb>thoughts in favor of either part of the <lb></lb>Queſtion. </s></p><p type="main"> <s>Firſt then, divers Naturaliſts eſteem the <lb></lb>Air (as well as other Elements) to be in<lb></lb>generable and incorruptible. </s> <s>And reaſons <lb></lb>plauſible enough may be drawn to coun<lb></lb>tenance this Opinion from the conſidera<lb></lb>tion of that permanency that ought to <lb></lb>belong to the corporeal Principles of o<lb></lb>ther Bodies. </s></p><p type="main"> <s>Next, Experience may be pleaded to <lb></lb>the ſame purpoſe, for I have read of ſome <lb></lb>who have in vain attempted to turn Air <lb></lb>into Water, or VVater into Air. </s></p><p type="main"> <s>The diligent <emph type="italics"></emph>Schottus<emph.end type="italics"></emph.end> tells us, That a<lb></lb><arrow.to.target n="marg25"></arrow.to.target><lb></lb>mongſt the other rarities to be met with <lb></lb>in that great Repoſitory of them, the <lb></lb><emph type="italics"></emph>Muſæum Kercherianum,<emph.end type="italics"></emph.end> there is a round <lb></lb>Glaſs with a tapering Neck near half full <lb></lb>(as one may gueſs by the Scheme he an<lb></lb>nexes) of ordinary Spring-water, which <lb></lb>having been Hermetically ſhut up there <lb></lb>by <emph type="italics"></emph>Clavius<emph.end type="italics"></emph.end> the famous Geometrician, <lb></lb>The included water is to this day pre<lb></lb>ſerv'd, not onely clear and pure, as if <lb></lb>it were but newly put in: But (as it ſeems) <pb xlink:href="013/01/194.jpg" pagenum="164"></pb>without (in the leaſt) turning into Air, <lb></lb>notwithſtanding its having been kept <lb></lb>there theſe fifty years: For he tells us, <lb></lb>That the Water hath continued there all <lb></lb>this while without any diminution. </s></p><p type="margin"> <s><margin.target id="marg25"></margin.target><emph type="italics"></emph>Schottus <lb></lb><gap></gap><emph.end type="italics"></emph.end><lb></lb>Part 3. <lb></lb>Claſſ. </s> <s>1.</s></p><p type="main"> <s>Nor does it appear in thoſe Glaſſes, <lb></lb>which for Chymical Experiments we uſu<lb></lb>ally cloſe with <emph type="italics"></emph>Hermes<emph.end type="italics"></emph.end> his Seal (as they <lb></lb>call it) that the included Air does, during <lb></lb>its long Impriſonment, notwithſtanding <lb></lb>the alteration it receives from various de<lb></lb>grees of heat, diſcernably alter its nature. <lb></lb></s> <s>Whereas we plainly perceive in our Dige<lb></lb>ſtions and Diſtillations, that though it <lb></lb>may be rarified into inviſible Vapors, yet <lb></lb>it is not really chang'd into Air, but onely <lb></lb>divided by heat, and ſcatter'd into very <lb></lb>minute parts, which meeting together in <lb></lb>the Alembick or in the Receiver, do pre<lb></lb>ſently return into ſuch Water as they con<lb></lb>ſtituted before. </s> <s>And we alſo ſee, that <lb></lb>ev'n Spirit of Wine, and other ſubtle and <lb></lb>fugitive Spirits, though they eaſily fly in<lb></lb>to the Air, and mingle with it, do yet in <lb></lb>the Glaſſes of Chymiſts eaſily lay aſide <lb></lb>the diſguiſe of Air, and reſume the deve<lb></lb>ſted form of Liquors. </s> <s>And ſo volatile <lb></lb>Salts, as of Urine, Harts-horn, <emph type="italics"></emph>&c.<emph.end type="italics"></emph.end> though <lb></lb>they will readily diſperſe themſelves <pb xlink:href="013/01/195.jpg" pagenum="165"></pb>through the Air, and play up and down in <lb></lb>the capacity of an Alembick or a Recei<lb></lb>ver: yet will they, after a while, faſten <lb></lb>themſelves to the inſides of ſuch Glaſſes <lb></lb>in the form of Salts. </s></p><p type="main"> <s>Beſides, ſince Air is confeſſedly en<lb></lb>dow'd with an Elaſtical power that proba<lb></lb>bly proceeds from its Texture, it appears <lb></lb>not what it is that in ſuch light alterations <lb></lb>of Water, as are by many preſum'd ca<lb></lb>pable of turning it into Air, can be rea<lb></lb>ſonably ſuppoſ'd ſo to contrive the Parti<lb></lb>cles of Water, as to give them, and that <lb></lb>permanently, the ſtructure requiſite to a <lb></lb>Spring. </s> <s>I adde the word, Permanently, <lb></lb>becauſe the newly mention'd obſervations <lb></lb>ſeem to argue the Corpuſcles of Air to <lb></lb>be irreducible into Water, whereas the <lb></lb>Aqueous Particles may perhaps for a <lb></lb>while be ſo vehemently agitated, as to <lb></lb>preſs almoſt like Springs upon other Bo<lb></lb>dies; yet upon the ceaſing of the agitati<lb></lb>on, they quickly, by relapſing into Wa<lb></lb>ter, diſcloſe themſelves to have been no<lb></lb>thing elſe whil'ſt they counterfeited the <lb></lb>Air. </s></p><p type="main"> <s>Laſtly, The Experiment formerly made <lb></lb>in our Engine with a piece of Match, <lb></lb>ſeems to evince, that even thoſe light and <pb xlink:href="013/01/196.jpg" pagenum="166"></pb>ſubtle Fumes (for the moſt part not aque<lb></lb>ous neither) into which the Fire it ſelf <lb></lb>ſhatters dry Bodies, have no ſuch Spring <lb></lb>in them as the Air, ſince they were unable <lb></lb>to hinder or repreſs the expanſion of the <lb></lb>Air included in the Bladder they ſurroun<lb></lb>ded. </s></p><p type="main"> <s>I remember indeed that the Learned <lb></lb><arrow.to.target n="marg26"></arrow.to.target><lb></lb><emph type="italics"></emph>Foſephus Acoſta,<emph.end type="italics"></emph.end> in his Hiſtory of the <lb></lb><emph type="italics"></emph>Weſt Indies,<emph.end type="italics"></emph.end> tells us, That he ſaw in thoſe <lb></lb>parts ſome Grates of Iron ſo ruſted and <lb></lb>conſum'd by the Air, that the Metal be<lb></lb>ing preſſ'd between the Fingers, diſſolv'd <lb></lb>(to uſe his words) to powder, as if it had <lb></lb>been Hay or parched Straw. </s> <s>And I re<lb></lb><arrow.to.target n="marg27"></arrow.to.target><lb></lb>member too, that the accurate <emph type="italics"></emph>Varenius<emph.end type="italics"></emph.end><lb></lb>tells us, That in the Iſlands commonly <lb></lb>called <emph type="italics"></emph>Azores,<emph.end type="italics"></emph.end> the Air (and Wind) is ſo <lb></lb>ſharp, that in a ſhort time it frets not only <lb></lb>Iron Plates, but the very Tiles upon the <lb></lb>Roofs of Houſes, and reduces them to <lb></lb>duſt. </s> <s>And I have elſewhere mention'd <lb></lb>ſome recent Obſervations of this kinde. <lb></lb></s> <s>But it may be ſaid, That the above-men<lb></lb>tion'd Authors aſcribe the recited effects <lb></lb>chiefly to the Winds, and that however <lb></lb>the corroſion of the Iron and the Tiles <lb></lb>may proceed not from the Air it ſelf, or <lb></lb>any of its genuine parts, but from ſome <pb xlink:href="013/01/197.jpg" pagenum="167"></pb>ſaline Corpuſcles diſperſ'd through the <lb></lb>Air, and driven by the Winds againſt the <lb></lb>Bodies it is preſum'd to fret. </s> <s>And that <lb></lb>ſuch volatile Salts may copiouſly aſcend <lb></lb>into the Air, and yet retain their Nature, <lb></lb>as doth the more fixt Salt in the Sea Wa<lb></lb>ter, the ſublimations of <emph type="italics"></emph>Sal-Armoniack<emph.end type="italics"></emph.end><lb></lb>may ſufficiently evince. </s> <s>Not to mention <lb></lb>that I have ſhown ſome Friends a ſecret <lb></lb>kinde of ſaline Subſtance incomparably <lb></lb>ſubtler then <emph type="italics"></emph>Sal-Armoniack,<emph.end type="italics"></emph.end> which did <lb></lb>not onely eaſily enough aſcend it ſelf, but <lb></lb>carried up with it (and that in a very great <lb></lb>proportion) the ſolid and ponderous Bo<lb></lb>dy ev'n of uncalcin'd Gold in the form of <lb></lb>ſubtle exhalations, which did afterwards <lb></lb>faſten themſelves to the upper parts of <lb></lb>the Veſſels, and yet manifeſt themſelves <lb></lb>to continue Gold. </s> <s>We remember alſo, <lb></lb>that to try whether Water could be turn'd <lb></lb>into Air, we once took an <emph type="italics"></emph>Æolipile,<emph.end type="italics"></emph.end> into <lb></lb>which we had before convey'd ſome Wa<lb></lb>ter, and placing it upon kindled Coals <lb></lb>when the heat forc'd out a vehement <lb></lb>ſtream of aqueous Vapors; we ty'd about <lb></lb>the neck of it, that of a Bladder, which <lb></lb>we had before empty'd of Air; and find<lb></lb>ing the <emph type="italics"></emph>Æolipile<emph.end type="italics"></emph.end> after a while to blow up <lb></lb>the Bladder, we carefully ty'd it again <pb xlink:href="013/01/198.jpg" pagenum="168"></pb>that the included ſubſtance might not get <lb></lb>away. </s> <s>Then ſlipping it off from the <emph type="italics"></emph>Æo<lb></lb>lipile<emph.end type="italics"></emph.end> we convey'd it into our Receiver, to <lb></lb>try whether or no that which in part di<lb></lb>ſtended the Bladder would appear by its <lb></lb>Spring to be true Air: whereby we found <lb></lb>that upon the exſuction of the ambient <lb></lb>Air, the included ſubſtance expanded it <lb></lb>ſelf and the Bladder to a very much great<lb></lb>er bulk then it was of before. </s> <s>And for <lb></lb>further ſatisfaction, having again taken <lb></lb>out the Bladder, we ſuffer'd it to remain <lb></lb>ty'd up till next morning, to try whether <lb></lb>time, and the coldneſs of the night, would <lb></lb>make the contain'd ſubſtance relapſe in<lb></lb>to Water: But the next Morning we <lb></lb>found it little leſs tumid then before. </s> <s>I <lb></lb>remember, I ſay, that I once made this <lb></lb>Experiment; but I might ſay in anſwer <lb></lb>to it, that the chief reaſon of my men<lb></lb>tioning it, is, To let Your Lordſhip ſee <lb></lb>how requiſite it is to be circumſpect and <lb></lb>conſiderate, when we are to make and to <lb></lb>build upon nice Experiments. </s> <s>For though <lb></lb>I may ſeem to have uſed ſufficient cauti<lb></lb>on, yet afterward conſidering with my <lb></lb>ſelf that the <emph type="italics"></emph>Æolipile<emph.end type="italics"></emph.end> I had imploy'd was <lb></lb>a very large one, and that it required much <lb></lb>more care then one that has not try'd it <pb xlink:href="013/01/199.jpg" pagenum="169"></pb>would imagine, to drive out all the Air <lb></lb>from a large <emph type="italics"></emph>Æolipile,<emph.end type="italics"></emph.end> I eaſily ſuſpected <lb></lb>that the diſtenſion of the Bladder in our <lb></lb>pneumatical Veſſel, might proceed not <lb></lb>from the Watery ſteams that came out at <lb></lb>the narrow mouth of the <emph type="italics"></emph>Æolipile,<emph.end type="italics"></emph.end> and <lb></lb>had very much wetted the Bladder, but <lb></lb>from the rarified Air which in that ſort of <lb></lb>Veſſels is wont for a good while together <lb></lb>to come out with the rarified Water: and <lb></lb>accordingly having reiterated the Experi<lb></lb>ment I found it very difficult (by rea<lb></lb>ſon of the ſhrinking of the Bladders (up<lb></lb>on their being heated) and of other impe<lb></lb>diments) to make it ſo accurately as to de<lb></lb>duce from it, that Water may be rarified <lb></lb>into true Air. </s></p><p type="margin"> <s><margin.target id="marg26"></margin.target><emph type="italics"></emph>Natural & <lb></lb><gap></gap> Hiſt. <lb></lb><gap></gap> In<lb></lb><gap></gap>,<emph.end type="italics"></emph.end> Lib. 3. <lb></lb><gap></gap> 9.</s></p><p type="margin"> <s><margin.target id="marg27"></margin.target><emph type="italics"></emph>Geogr. </s> <s>Ge<lb></lb><gap></gap>ral.<emph.end type="italics"></emph.end></s><s> Lib. <lb></lb><gap></gap> 19.</s></p><p type="main"> <s>Againſt the four other above-mention'd <lb></lb>Conſiderations, we cannot ſpend time to <lb></lb>frame Objections, but muſt forth with <lb></lb>proceed to the mention of thoſe things <lb></lb>that ſeem to argue that Air (at leaſt ſuch <lb></lb>as produc'd our bubbles) maybe gene<lb></lb>rated of Water and other Bodies. </s></p><p type="main"> <s>Firſt then we have found by Experi<lb></lb>ence that a vapid Air, or Water rarified <lb></lb>into vapor, may at leaſt for a while emu<lb></lb>late the elaſtical power of that which is <lb></lb>generally acknowledg'd to be true Air. <pb xlink:href="013/01/200.jpg" pagenum="170"></pb>For if you take a good <emph type="italics"></emph>Æolipile,<emph.end type="italics"></emph.end> with a <lb></lb>moderately ſtrong and ſlender Neck, and <lb></lb>filling it with Water, lay it upon quick <lb></lb>Coals, you may after a while obſerve ſo <lb></lb>great a preſſure by ſome of the parts con<lb></lb>tain'd in the <emph type="italics"></emph>Æolipile<emph.end type="italics"></emph.end> upon others, that <lb></lb>the Water will ſometimes be thrown up <lb></lb>into the Air above three or four Foot <lb></lb>high; and if you then take the <emph type="italics"></emph>Æolipile<emph.end type="italics"></emph.end><lb></lb>almoſt red hot from off the Fire, you may <lb></lb>perceive that the Water will for a longer <lb></lb>time then one would eaſily imagine con<lb></lb>tinue to be ſpouted out in a violent <lb></lb>Stream. </s> <s>And if there remains but little <lb></lb>Water in the <emph type="italics"></emph>Æolipile<emph.end type="italics"></emph.end> when tis taken ve<lb></lb>ry hot from the Fire, immerfing the <lb></lb>Neck of it into cold Water, you will <lb></lb>finde, that after it begins to ſuck in ſome <lb></lb>Water, there will be made from time to <lb></lb>time ſtore of large bubbles in that Water <lb></lb>where into the neck was plunged. </s> <s>Which <lb></lb>bubbles ſeem manifeſtly to proceed from <lb></lb>hence, that for a while the heat in the <emph type="italics"></emph>Æ<lb></lb>olipile<emph.end type="italics"></emph.end> continues ſtrong enough to rarifie <lb></lb>part of the Water that is ſuck'd in, and <lb></lb>expel it in the form of Vapors through <lb></lb>the Water incumbent on the Pipe. </s> <s>If al<lb></lb>ſo when the <emph type="italics"></emph>Æolipile<emph.end type="italics"></emph.end> is almoſt full of wa<lb></lb>ter, and therefore can contain but little <pb xlink:href="013/01/201.jpg" pagenum="171"></pb>Air; you hold a Coal or Brand in that <lb></lb>ſtream of Vapors that iſſues out of the <lb></lb>narrow mouth of it, you will finde this <lb></lb>vapid or rorid Air, (if I may ſo call it) <lb></lb>to blow the Fire very ſtrongly and with a <lb></lb>roaring noiſe. </s> <s>And that it be not ſaid <lb></lb>that 'tis by the external Air which the a<lb></lb>queous ſteams drive before them, and <lb></lb>not by the Steams themſelves, that the <lb></lb>Blaſt is made and the Flame excited; it <lb></lb>has been obſerv'd, that by approaching <lb></lb>the Coal or Brand almoſt to the mouth <lb></lb>of the <emph type="italics"></emph>Æolipile,<emph.end type="italics"></emph.end> the winde appear'd more <lb></lb>vehement then if the Body to be kindled <lb></lb>were held ſome Inches off. </s></p><p type="main"> <s>But in regard the elaſtical power of the <lb></lb>Stream, iſſuing out of an <emph type="italics"></emph>Æolipile,<emph.end type="italics"></emph.end> ſeems <lb></lb>manifeſtly due to the heat that expands <lb></lb>and agitates the aqueous Particles where<lb></lb>of that Stream conſiſts, and that ſuch <lb></lb>rapid winds ſeem to be but water ſcatter'd <lb></lb>into little parts and ſet a moving; ſince <lb></lb>we finde, that holding a Knife, or any <lb></lb>ſolid, ſmooth and cloſe Body againſt the <lb></lb>ſtream that iſſues out of the Æolipile, the <lb></lb>vapors condenſing upon it, will preſently <lb></lb>cover it with water: It will be very per<lb></lb>tinent to ſubjoyn a notable Experiment <lb></lb>that I remember I have met with in the <pb xlink:href="013/01/202.jpg" pagenum="172"></pb>deſcription given us by the Induſtrious <lb></lb><emph type="italics"></emph>Kircher,<emph.end type="italics"></emph.end> of ſeveral Muſical Engines. </s> <s>And <lb></lb>(though it may ſeem ſomewhat prolix) <lb></lb>we will recite what he delivers in his own <lb></lb>words, which are theſe. </s></p><p type="main"> <s><emph type="italics"></emph>Cum codem tempore quo hæc ſcripſi<emph.end type="italics"></emph.end><lb></lb><arrow.to.target n="marg28"></arrow.to.target><lb></lb><emph type="italics"></emph>ſummi Pont: Innocentii<emph.end type="italics"></emph.end> X<emph type="sup"></emph>mi<emph.end type="sup"></emph.end> <emph type="italics"></emph>mandato or<lb></lb>gani hydraulici in horto Quirinali conſti<lb></lb>tuendi cur a mihi commendata eſſet; Æoliam <lb></lb>camer am inſigni ſane ſucceſſu conſtrui juſsi<lb></lb>mus, eá quæ ſequitur ratione.<emph.end type="italics"></emph.end></s></p><p type="margin"> <s><margin.target id="marg28"></margin.target><emph type="italics"></emph>Kirch: Art: <lb></lb>Mag: Con: <lb></lb>& Diſſon: <lb></lb>lib.<emph.end type="italics"></emph.end> 9. <lb></lb>p. 309.</s></p><p type="main"> <s><emph type="italics"></emph>Erat longitudo ſive altitudo cameræ<emph.end type="italics"></emph.end> AH <lb></lb>5 <emph type="italics"></emph>Pedum, Latitudine<emph.end type="italics"></emph.end> 3 <emph type="italics"></emph>fere ex lateribus<emph.end type="italics"></emph.end><lb></lb><arrow.to.target n="marg29"></arrow.to.target><lb></lb><emph type="italics"></emph>conſtructa; in medio duo tenebat Diaphrag<lb></lb>mata<emph.end type="italics"></emph.end> CD <emph type="italics"></emph>&<emph.end type="italics"></emph.end> EJ <emph type="italics"></emph>in modum cribri pluri<lb></lb>bus for aminibus pertuſa. </s> <s>Paulo infra ca<lb></lb>nalis<emph.end type="italics"></emph.end> G <emph type="italics"></emph>aquam advehens inſerebatur in<emph.end type="italics"></emph.end> H <lb></lb><emph type="italics"></emph>eidem epiſtomium par ab at exitum. </s> <s>Aqua <lb></lb>it áque per canalem<emph.end type="italics"></emph.end> G <emph type="italics"></emph>maximo impetu ruens <lb></lb>vehementiſsimum ventum mox intus exci<lb></lb>t ab at; qui ventus nimia humiditate imbu<lb></lb>tus, ut purior exiret ſiccior〈qué〉, Diaphrag<lb></lb>mata ill a in cribri modum pertuſa, or dinata <lb></lb>ſunt. </s> <s>Intra hæc enim aquæ vehemens agi<lb></lb>tatio rupta fracta〈qué〉 aerem puriorem per<emph.end type="italics"></emph.end> A <lb></lb><emph type="italics"></emph>canalem ſubtilioremque emittebat: Verum <lb></lb>cum poſtea <expan abbr="inventũ">inventum</expan> ſit <expan abbr="aerẽ">aerem</expan> plus æquo <expan abbr="humi-dũ">humi<lb></lb>dum</expan> interioribus Organi meatibus <expan abbr="maximũ">maximum</expan> <lb></lb>detrimentum inferre: Hinc ut aer aquoſus<emph.end type="italics"></emph.end><pb xlink:href="013/01/203.jpg" pagenum="173"></pb><emph type="italics"></emph>ſicciſsimam <expan abbr="cõſiſtentiam">conſiſtentiam</expan> acquireret, ordina<lb></lb>vimus canalem plumbeum<emph.end type="italics"></emph.end> QR <emph type="italics"></emph>in helicem <lb></lb>contortum vaſi<emph.end type="italics"></emph.end> S <emph type="italics"></emph>aliquantulum capaciori in <lb></lb>modum Urnæ efformato, inſertum. </s> <s>Intra <lb></lb>urnam enim plumbeam & canalem tortuo<lb></lb>ſum illiſus aer humidus, it a ab omni aquoſi<lb></lb>tate defæcabatur, ut ex furno in Organum <lb></lb>derivatus dici potuerit. </s> <s>Urna<emph.end type="italics"></emph.end> S <emph type="italics"></emph>canalis <lb></lb>tortuoſus<emph.end type="italics"></emph.end> QR <emph type="italics"></emph>ultimum orificium<emph.end type="italics"></emph.end> Q <emph type="italics"></emph>inſe<lb></lb>ritur anemothecæ organi. </s> <s>Et hunc modum <lb></lb>organis hydraulicis <expan abbr="omniũ">omnium</expan> <expan abbr="aptiſsimũ">aptiſsimum</expan> reperi.<emph.end type="italics"></emph.end></s></p><p type="margin"> <s><margin.target id="marg29"></margin.target><emph type="italics"></emph>See the fif<lb></lb>teenth Fi<lb></lb>gure.<emph.end type="italics"></emph.end></s></p><p type="main"> <s><emph type="italics"></emph>Debet autem cameræ illa ſituari in loco <lb></lb>quantum fieri poteſt ſicciori it a ut longo ca<lb></lb>nali aqua intr a eam derivetur ne locus hu<lb></lb>miditate ſua Organis officiat.<emph.end type="italics"></emph.end></s></p><p type="main"> <s>Thus far the Ingenious <emph type="italics"></emph>Kircherus,<emph.end type="italics"></emph.end> whom <lb></lb>I the rather cite, becauſe although I have <lb></lb>been informed of divers Ventiducts (as <lb></lb>they call them) by very knowing Tra<lb></lb>vellers that have obſerv'd them: Yet this <lb></lb>relation of our Author being very pun<lb></lb>ctual, and deliver'd upon his own particu<lb></lb>lar Experience, has, I confeſs, made me <lb></lb>wiſh I had had the good fortune when I <lb></lb>was at <emph type="italics"></emph>Rome,<emph.end type="italics"></emph.end> to take notice of theſe Or<lb></lb>gans; or that I had now the opportunity <lb></lb>of examining of ſuch an Experiment. <lb></lb></s> <s>For if upon a ſtrict inquiry I ſhould find <lb></lb>that the breath that blows the Organs <pb xlink:href="013/01/204.jpg" pagenum="174"></pb>does not really upon the ceaſing of its un<lb></lb>uſual agitation by little and little relapſe <lb></lb>into water, I ſhould ſtrongly ſuſpect that <lb></lb>'tis poſſible for Water to be eaſily turn'd <lb></lb>into Air. </s> <s>I remember indeed, that we <lb></lb>have formerly taught that there lurks an <lb></lb>interſperſed Air in the pores of ordinary <lb></lb>Water, which may poſſibly be ſtruck out <lb></lb>by the breaking of the Water in its fall <lb></lb>into the Æolian Chamber, (as he calls it.) <lb></lb>But in regard the Scheme ſeems to repre<lb></lb>ſent that Chamber as cloſely ſhut, and <lb></lb>thereby forbids us to ſuppoſe that any Air <lb></lb>is carried into it but what is latitant in the <lb></lb>Water, it will ſcarce ſeem probable to <lb></lb>him who remembers how ſmall a propor<lb></lb>tion of Air, that appear'd to be when its <lb></lb>rarification ſeaſed, which was conceal'd in <lb></lb>the Water we freed from bubbles in our <lb></lb>Receiver, that ſo little Air as is common<lb></lb>ly diſperſ'd through Water, ſhould be a<lb></lb>ble, in ſo little Water as was requiſite for <lb></lb>ſo ſmall a room, to make ſo vehement a <lb></lb>Wind as our Author here tells us of. </s> <s>I <lb></lb>have ſometime therefore ſuſpected, that <lb></lb>in this caſe the Wind may be produc'd by <lb></lb>ſmall particles of the water it ſelf, forci<lb></lb>bly expell'd out of the Chamber into the <lb></lb>Organs. </s> <s>And to the Objection to which <pb xlink:href="013/01/205.jpg" pagenum="175"></pb>I foreſaw this gheſs to be liable, namely, <lb></lb>That, no heat intervening, there appear'd <lb></lb>nothing that ſhould raiſe the Water into <lb></lb>exhalations and give them an impulſe. </s> <s>I <lb></lb>thought it might be ſaid that motion a<lb></lb>lone, if vehement enough, may, with<lb></lb>out ſenſible heat, ſuffice to break Water <lb></lb>into very minute parts, and make them aſ<lb></lb>cend upwards, if they can no where elſe <lb></lb>more eaſily continue their agitation. </s> <s>For <lb></lb>Iremember, that Travelling betwixt <emph type="italics"></emph>Ly<lb></lb>ons<emph.end type="italics"></emph.end> and <emph type="italics"></emph>Geneva,<emph.end type="italics"></emph.end> I ſaw, not very far out of <lb></lb>the Way, a place where the River of <lb></lb><emph type="italics"></emph>Rhone<emph.end type="italics"></emph.end> coming ſuddenly to be ſtreighten'd <lb></lb>betwixt two Rocks, ſo near each other, <lb></lb>that a Man may (if my Memory fail me <lb></lb>not) ſtand aſtride upon both at once: that <lb></lb>rapid Stream daſhing with great impetuo<lb></lb>ſity againſt its Rocky Boundaries, does <lb></lb>break part of its Water into ſuch minute <lb></lb>Corpuſcles, and put them into ſuch a mo<lb></lb>tion, that Paſſengers obſerve at a good di<lb></lb>ſtance off, as it were a Miſt ariſing from <lb></lb>that place, and aſcending a good way up <lb></lb>into the Air. </s> <s>Such, I ſay, was my ſuſ<lb></lb>picion touching the Wind we have been <lb></lb>conſidering, but it ſeems ſomething odde <lb></lb>that aqueous Vapors ſhould, like a dry <lb></lb>Wind, paſs through ſo long and tortu-<pb xlink:href="013/01/206.jpg" pagenum="176"></pb>ous a Pipe of Lead, as that deſcrib'd by <lb></lb>our Author, ſince we ſee in the Heads of <lb></lb>Stills, and the Necks of <emph type="italics"></emph>Æolipiles,<emph.end type="italics"></emph.end> how <lb></lb>quickly ſuch vapors are even by a very lit<lb></lb>tle cold recondenſed into Water. </s> <s>But <lb></lb>to this alſo ſomething may be ſpeciouſly <lb></lb>reply'd; wherefore contenting my ſelf to <lb></lb>have mention'd our Authors Experiment <lb></lb>as a plauſible, though not demonſtrative <lb></lb>proof, that Water may be tranſmuted in<lb></lb>to Air. </s> <s>We will paſs on to mention in <lb></lb>the third place another Experiment, which <lb></lb>we try'd in order to the ſame enquiry. </s></p><p type="main"> <s>We took a clear Glaſs bubble (capable <lb></lb>of containing by gheſs about three Oun<lb></lb>ces of Water) with a Neck ſomewhat <lb></lb>long and wide, of a Cylindrical form; <lb></lb>this we fill'd with Oyl of Vitriol and fair <lb></lb>water, of each almoſt a like quantity, and <lb></lb>caſting in half a dozen ſmall Iron Nails, <lb></lb>we ſtopt the mouth of the Glaſs (which <lb></lb>was top-full of Liquor) with a flat piece <lb></lb>of <emph type="italics"></emph>Diapalma<emph.end type="italics"></emph.end> provided for the purpoſe, <lb></lb>that accommodating it ſelf to the ſurface <lb></lb>of the water, the Air might be exqui<lb></lb>ſitely excluded: and ſpeedily inverting <lb></lb>the Viol, we put the Neck of it into a <lb></lb>ſmall wide-mouth'd Glaſs that ſtood rea<lb></lb>dy with more of the ſame Liquor in it, to <pb xlink:href="013/01/207.jpg" pagenum="177"></pb>receive it. </s> <s>As ſoon as the neck had reach'd <lb></lb>the bottom of the Liquor it was dipp'd <lb></lb>into, there appear'd at the upper part <lb></lb>(which was before the bottom) of the <lb></lb>Viol a bubble, of about the bigneſs of <lb></lb>a Pea, which ſeem'd rather to conſiſt of <lb></lb>ſmall and recent bubbles, produc'd by the <lb></lb>action of the diſſolving Liquor upon the <lb></lb>Iron, then any parcel of the external Air <lb></lb>that might be ſuſpected to have got in <lb></lb>upon the inverſion of the Glaſs, eſpeci<lb></lb>ally ſince we gave time to thoſe little <lb></lb>Particles of Air which were carried down <lb></lb>with the Nails into the Liquor to fly up <lb></lb>again. </s> <s>But whence this firſt bubble was <lb></lb>produced, is not ſo material to our Expe<lb></lb>riment, in regard it was ſo ſmall: For <lb></lb>ſoon after we perceiv'd the bubbles <lb></lb>produced by the action of the <emph type="italics"></emph>Men<lb></lb>ſtruum,<emph.end type="italics"></emph.end> upon the Metal aſcending co<lb></lb>piouſly to the bubble already named, and <lb></lb>breaking into it, did ſoon exceedingly in<lb></lb>creaſe it, and by degrees depreſs the wa<lb></lb>ter lower and lower, till at length the ſub<lb></lb>ſtance contain'd in theſe bubbles poſſeſſed <lb></lb>the whole cavity of the Glaſs Viol, and <lb></lb>almoſt of its Neck too, reaching much <lb></lb>lower in the Neck then the ſurface of the <lb></lb>ambient Liquor, wherewith the open<lb></lb>mouth'd Glaſs was by this means almoſt <pb xlink:href="013/01/208.jpg" pagenum="178"></pb>repleniſhed. </s> <s>And becauſe it might be <lb></lb>ſuſpected that the depreſſion of the Li<lb></lb>quor might proceed from the agitation <lb></lb>whereinto the exhaling and impriſon'd <lb></lb>ſteams were put, by that heat which is <lb></lb>wont to reſult from that action of corro<lb></lb>ſive ſalts upon Metals, we ſuffered both <lb></lb>the Viol and the open-mouthed Glaſs to <lb></lb>remain as they were, in a Window, for <lb></lb>three or four days and nights together; but <lb></lb>looking upou them ſeveral times during <lb></lb>that while, as well as at the expiration of <lb></lb>it, the whole cavity of the Glaſs bubble, <lb></lb>and moſt of its Neck, ſeem'd to be poſ<lb></lb>ſeſſ'd by Air, ſince by its ſpring it was a<lb></lb>ble for ſo long to hinder the expell'd and <lb></lb>ambient Liquor from regaining its former <lb></lb>place. </s> <s>And it was remarkable, that juſt <lb></lb>before we took the Glaſs bubble out of <lb></lb>the other Glaſs, upon the application <lb></lb>of a warm hand to the convex part of the <lb></lb>bubble; the Impriſon'd ſubſtance readily <lb></lb>dilated it ſelf like Air, and broke through <lb></lb>the Liquor in divers bubbles, ſucceeding <lb></lb>one another. </s></p><p type="main"> <s>Having alſo another time try'd the like <lb></lb>Experiment with a ſmall Viol, and with <lb></lb>Nails diſſolv'd in <emph type="italics"></emph>Aquafortis,<emph.end type="italics"></emph.end> we found <lb></lb>nothing incongruous to what we have <lb></lb>now deliver'd. </s> <s>And this Circumſtance <pb xlink:href="013/01/209.jpg" pagenum="179"></pb>we obſerv'd, that the newly generated <lb></lb>ſteams did not onely poſſeſs almoſt all the <lb></lb>whole cavity of the Glaſs, but divers <lb></lb>times without the aſſiſtance of the heat of <lb></lb>my hand, broke away in large bubbles <lb></lb>through the ambient Liquor into the o<lb></lb>pen Air: So that theſe Experiments <lb></lb>with corroſive Liquors, ſeem'd manifeſt<lb></lb>ly enough to prove, though not that Air <lb></lb>may be generated out of the Water, yet <lb></lb>that in general air may be generated anew. </s></p><p type="main"> <s>Laſtly, to the foregoing Arguments <lb></lb>from Experience we might eaſily ſubjoyn <lb></lb>the Authority of <emph type="italics"></emph>Ariſtotle,<emph.end type="italics"></emph.end> and of (his <lb></lb>followers) the Schools who are known to <lb></lb>have taught, that Air and Water being <lb></lb>Symbolizing Elements (in the quality of <lb></lb>moiſture) are eaſily tranſmutable into one <lb></lb>another. </s> <s>But we ſhall rather to the fore<lb></lb>going Argument adde this, drawn from <lb></lb>Reaſon, That if, as <emph type="italics"></emph>Leucippus, Democri<lb></lb>tus, Epieurus<emph.end type="italics"></emph.end> and others, follow'd by <lb></lb>divers modern Naturaliſts, have taught, <lb></lb>the difference of Bodies proceeds but <lb></lb>from the various Magnitudes, Figures, <lb></lb>Motions, and Textures of the ſmall <lb></lb>parts they conſiſt of, (all the quali<lb></lb>ties that make them differ, being de<lb></lb>ducible from thence) there appeares <pb xlink:href="013/01/210.jpg" pagenum="180"></pb>no reaſon why the minute parts of Wa<lb></lb>ter, and other Bodies, may not be ſo agi<lb></lb>tated or connected as to deſerve the name <lb></lb>of Air. </s> <s>For if we allow the <emph type="italics"></emph>Carteſian <lb></lb>Hypotheſis,<emph.end type="italics"></emph.end> according to which, as we no<lb></lb>ted at the beginning of this Letter, the <lb></lb>Air may conſiſt of any terrene or aqueous <lb></lb>Corpuſcles, provided they be kept ſwim<lb></lb>ming in the interfluent Celeſtial Matter; <lb></lb>it is obvious that Air may be as often ge<lb></lb>nerated, as Terreſtrial Particles minute <lb></lb>enough to be carried up and down, by the <lb></lb>Celeſtial Matter aſcend into the Atmo<lb></lb>ſphere. </s> <s>And if we will have the Air to <lb></lb>be a <emph type="italics"></emph>congeries<emph.end type="italics"></emph.end> of little ſlender Springs, it <lb></lb>ſeems not impoſſible, though it be diffi<lb></lb>cult, that the ſmall parts of divers Bo<lb></lb>dies may by a lucky concourſe of cauſes <lb></lb>be ſo connected as to conſtitute ſuch <lb></lb>little Springs, ſince (as we note in another <lb></lb>Treatiſe) Water in the Plants it nouriſhes <lb></lb>is uſually contriv'd into Springy Bodies, <lb></lb>and even the bare alter'd poſition and con<lb></lb>nexion of the parts of a Body may ſuf<lb></lb>fice to give it a Spring that it had not be<lb></lb>fore, as may be ſeen in a thin and fiexible <lb></lb>Plate of Silver; unto which, by ſome <lb></lb>ſtroaks of a Hammer, you may give a <lb></lb>Spring, and by onely heating it red hot <pb xlink:href="013/01/211.jpg" pagenum="181"></pb>you may make it again flexible as be<lb></lb>fore. </s></p><p type="main"> <s>Theſe, My Lord, are ſome of the <lb></lb>Conſiderations at preſent occurring to <lb></lb>my thoughts, by which it may be made <lb></lb>probable that Air may be generated a<lb></lb>new. </s> <s>And though it be not impoſſible <lb></lb>to propoſe Objections againſt theſe, as <lb></lb>well as againſt what has been repreſented <lb></lb>in favor of the contrary Doctrine; yet <lb></lb>having already almoſt tyr'd my ſelf, and <lb></lb>I fear more then almoſt tyr'd Your Lord<lb></lb>ſhip with ſo troubleſome an Enquiry af<lb></lb>ter the Nature of bubbles, I ſhall wil<lb></lb>lingly leave Your Lordſhip to judge of <lb></lb>the Arguments alledged on either ſide, <lb></lb>and I ſhould ſcarce have ventur'd to enter<lb></lb>tain You ſo long concerning ſuch empty <lb></lb>things as the Bubbles, which have occa<lb></lb>ſion'd all this Diſcourſe, but that I am <lb></lb>willing to invite You to take notice with <lb></lb>me of the obſcurity of things, or the dim<lb></lb>neſs of our created Intellects (which yet <lb></lb>of late too many ſo far preſume upon, as <lb></lb>either to Deny or Cenſure the Almighty <lb></lb>and Omniſcient Creator himſelf) and to <lb></lb>learn hence this Leſſon, That there are <lb></lb>very many Things in Nature that we diſ<lb></lb>dainfully over-look as obvious or deſpi-<pb xlink:href="013/01/212.jpg" pagenum="182"></pb>cable, each of which would exerciſe our <lb></lb>Underſtandings, if not poſe them too, if <lb></lb>we would but attentively enough conſider <lb></lb>it, and not ſuperficially contemplate, but <lb></lb>attempt ſatisfactorily to explicate the na<lb></lb>ture of it. </s></p><p type="main"> <s>SInce the writing of the twenty one and <lb></lb><arrow.to.target n="marg30"></arrow.to.target><lb></lb>twenty ſecond Experiments (and not<lb></lb>withſtanding all that hath been on their <lb></lb>occaſion deliver'd concerning bubbles) we <lb></lb>made ſome further tryals in proſecution <lb></lb>of the ſame inquiry whereto they were <lb></lb>deſigned. </s></p><p type="margin"> <s><margin.target id="marg30"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 23.</s></p><p type="main"> <s>We choſe then, amongſt thoſe Glaſſes <lb></lb>which Chymiſts are wont to call Philoſo<lb></lb>phical Eggs, one that containing about <lb></lb>nine Ounces of Water, had a Neck of <lb></lb>half an Inch in Diameter at the top, and <lb></lb>as we gheſt, almoſt an Inch at the bot<lb></lb>tom; which breadth we pitch'd upon for <lb></lb>a reaſon that will by and by appear: then <lb></lb>filling it with common Water to the <lb></lb>height of about a Foot and a half, ſo <lb></lb>that the upper part remain'd empty, we <lb></lb>ſhut it into the Receiver, and watch'd what <lb></lb>would follow upon pumping, which pro-<pb xlink:href="013/01/213.jpg" pagenum="183"></pb>ved that a great part of the Air being <lb></lb>drawn out, the bubbles began to diſcover <lb></lb>themſelves at the bottom and ſides of the <lb></lb>Glaſs; and increaſing, as the Air was <lb></lb>more and more drawn away, they did <lb></lb>from time to time aſcend copiouſly e<lb></lb>nough to the top of the Water, and there <lb></lb>quickly break: but by reaſon that the <lb></lb>wideneſs of the Glaſs allow'd them free <lb></lb>paſſage through the Water, they did not <lb></lb>appear as in the former Experiments to <lb></lb>make it ſwell: The Water ſcarce ever ri<lb></lb>ſing at all above the mark affixt to its up<lb></lb>per ſurface when it was put in, and upon <lb></lb>the return permitted to the outward Air, <lb></lb>and conſequently the ſhrinking in of the <lb></lb>remaining bubbles, the Water ſeem'd to <lb></lb>have loſt of its firſt extent, by the avo<lb></lb>lation of the formerly interſperſ'd Air. </s></p><p type="main"> <s>Being willing likewiſe to try whether <lb></lb>diſtilled Water were by having been di<lb></lb>vided into minute parts, and then re-uni<lb></lb>ted, more or leſs diſpoſ'd to expand it <lb></lb>ſelf then Water not diſtill'd: We took <lb></lb>out of our Laboratory ſome careful<lb></lb>ly diſtill'd Rain-water, and put about <lb></lb>two Ounces of it into a round Glaſs <pb xlink:href="013/01/214.jpg" pagenum="184"></pb>bubble with a very ſmall Neck (not ex<lb></lb>ceeding the ſixth part of an Inch in Dia<lb></lb>meter) which we fill'd half way to the <lb></lb>top, and then convey'd it into the Recei<lb></lb>ver; the iſſue was, That though we drew <lb></lb>out more then ordinary, yet there ap<lb></lb>pear'd not the leaſt intumeſcence of the <lb></lb>Water, nor any aſcending bubbles. </s></p><p type="main"> <s>But ſuſpecting that either the ſmall <lb></lb>quantity of the water or the Figure of the <lb></lb>Veſſel might have an intereſt in this odde <lb></lb><emph type="italics"></emph>Phænomenon,<emph.end type="italics"></emph.end> we took the lately mention'd <lb></lb>Philoſophical Egge, and another not <lb></lb>much differing from it; the former we <lb></lb>fill'd up with diſtill'd Rain-water to the <lb></lb>old mark, and into the latter we put a <lb></lb>long Cylinder or Rod of ſolid Glaſs to <lb></lb>ſtreighten the cavity of the Neck by al<lb></lb>moſt filling it up; and then pouring ſome <lb></lb>diſtilled Water into that alſo, till it <lb></lb>reach'd within ſome Fingers breadth of <lb></lb>the top, the Eggs were let down into the <lb></lb>Receiver. </s> <s>In this Experiment the Air <lb></lb>was ſo far drawn forth before there ap<lb></lb>pear'd any bubble in either of the Glaſſes, <lb></lb>that the diſparity betwixt this and com<lb></lb>mon water was manifeſt enough. </s> <s>But at <lb></lb>length, when the Air was almoſt quite <lb></lb>pump'd out, the bubbles began to diſ-<pb xlink:href="013/01/215.jpg" pagenum="185"></pb>cloſe themſelves, and to increaſe as the <lb></lb>preſſure of the Air in the Receiver de<lb></lb>creaſ'd. </s> <s>But whereas in the firſt men<lb></lb>tion'd Philoſophical Egge the bubbles <lb></lb>were very ſmall, and never able to ſwell <lb></lb>the Water, that we took notice of, at all <lb></lb>above the mark: In the other, whoſe <lb></lb>Neck, as we lately ſaid, was ſtraightned, <lb></lb>and their paſſage obſtructed, great num<lb></lb>bers of them, and bigger, faſtned them<lb></lb>ſelves to the lower end of the Glaſs ram<lb></lb>mer (if we may ſo call it) and gather'd in <lb></lb>ſuch numbers between that and the ſides <lb></lb>of the Neck, that the Water ſwell'd a<lb></lb>bout a Fingers breadth above the mark, <lb></lb>though upon the admitting of the exter<lb></lb>nal Air it relapſ'd to the former mark, or <lb></lb>rather fell ſomewhat below it. </s> <s>And al<lb></lb>though thereupon in the firſt nam'd Veſ<lb></lb>ſel all the bubbles preſently diſ-appear'd, <lb></lb>yet in the other we obſerv'd, that divers <lb></lb>remained faſtned to the lower part of the <lb></lb>Glaſs rammer, and continued there ſome<lb></lb>what to our wonder, for above an hour <lb></lb>after, but contracted in their Dimen<lb></lb>ſions. </s></p><p type="main"> <s>Moreover, having ſuffered the Glaſſes <lb></lb>to remain above twenty four hours in the <pb xlink:href="013/01/216.jpg" pagenum="186"></pb>Receiver, we afterwards repeated the Ex<lb></lb>periment, to try what change the exſucti<lb></lb>on of the external Air would produce in <lb></lb>the Water, after the internal and latitant <lb></lb>Air had (as is above recited) in great mea<lb></lb>ſure got away in bubbles, and whether or <lb></lb>no the Water would by ſtanding re-admit <lb></lb>any new particles of Air in the room of <lb></lb>thoſe that had forſaken it. </s> <s>But though <lb></lb>we exhauſted the Receiver very diligent<lb></lb>ly, yet we ſcarce ſaw a bubble in either <lb></lb>of the Glaſſes; notwithſtanding which, <lb></lb>we perceiv'd the Water to riſe about the <lb></lb>breadth of a Barly-corn, or more, in the <lb></lb>Neck of that Glaſs wherein the ſolid Cy<lb></lb>linder had been put; The Liquor in the <lb></lb>other Glaſs not ſenſibly ſwelling. </s></p><p type="main"> <s>And laſtly, upon the letting in of the <lb></lb>Air, the Water in the ſtraightned Neck <lb></lb>ſoon ſubſided to the mark above which <lb></lb>it had ſwollen, which whether it ought <lb></lb>to be aſcrib'd to the ſame ſmall expanſion <lb></lb>of the parts of the Water it ſelf, or to <lb></lb>the rarifaction of ſome yet latitant Air <lb></lb>broken into ſuch ſmall particles, as to e<lb></lb>ſcape our obſervation, ſeems not eaſily <lb></lb>determinable, without ſuch further tryals, <lb></lb>as would perhaps prove tedious to be re<lb></lb>cited as well as to be made; though I was <pb xlink:href="013/01/217.jpg" pagenum="187"></pb>content to ſet down thoſe already men<lb></lb>tion'd, that it might appear how requi<lb></lb>ſite it is in nice Experiments to conſider <lb></lb>variety of Circumſtances. </s></p><p type="main"> <s>AFter having thus diſcover'd what ope<lb></lb><arrow.to.target n="marg31"></arrow.to.target><lb></lb>ration the exſuction of the ambient <lb></lb>Air had upon Water, we thought good <lb></lb>to try alſo what changes would happen in <lb></lb>other Liquors upon the like taking off the <lb></lb>preſſure of the external Air. </s> <s>We took <lb></lb>then a Glaſs Egge, ſomewhat bigger then <lb></lb>a Turkey Egge, which had a long Neck <lb></lb>or Stem of about a 1/3 part of an Inch in <lb></lb>Diameter; and filling it up with Sallet <lb></lb>Oyl until it reach'd above half way to the <lb></lb>top of the Neck, we incloſ'd it in the Re<lb></lb>ceiver together with common Water in <lb></lb>a reſembling Veſſel, that we might the <lb></lb>better compare together the operation of <lb></lb>the exſuction of the Air upon thoſe two <lb></lb>Liquors. </s> <s>The Pump being ſet a work there <lb></lb>began to appear bubbles in the Oyl much <lb></lb>ſooner then in the Water, and afterwards <lb></lb>they alſo aſcended much more copiouſly <lb></lb>in the former Liquor then the latter: Nay, <lb></lb>and when by having quite tired the Pum<lb></lb>per, and almoſt our own patience, we <pb xlink:href="013/01/218.jpg" pagenum="188"></pb>gave over, the bubbles riſe almoſt (if <lb></lb>not altogether) in as great numbers <lb></lb>as ever, inſomuch as none of the various <lb></lb>Liquors we tryed either before or ſince, <lb></lb>ſeem'd to abound more with Aerial Parti<lb></lb>cles then did this Oyl. </s> <s>In which it was <lb></lb>further remarkable, that between the time <lb></lb>it was ſet into the Receiver, and that at <lb></lb>which we could get ready to Pump, it ſub<lb></lb>ſided notably (by gheſs about half an <lb></lb>Inch) below the mark it reach'd before it <lb></lb>was put in. </s></p><p type="margin"> <s><margin.target id="marg31"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 24.</s></p><p type="main"> <s>After this expreſſ'd Oyl, we made tryal <lb></lb>of a diſtill'd one, and for that purpoſe <lb></lb>made choice of the common Oyl or Spi<lb></lb>rit (for in the Shops where it is ſold, the <lb></lb>ſame Liquor is promiſcuouſly call'd by ei<lb></lb>ther name) of Turpentine; becauſe 'twas <lb></lb>onely of that Chymical Oyl, we had a <lb></lb>ſufficient quantity: which, being put in<lb></lb>to a ſmall Glaſs bubble with a ſlender <lb></lb>Neck, ſo as to fill it to about two Inches <lb></lb>from the top, did, upon the evacuating <lb></lb>of the Receiver, preſent us with great <lb></lb>ſtore of bubbles; moſt of which riſing <lb></lb>from the bottom, expanded themſelves <lb></lb>exceedingly in their aſcent, and made the <lb></lb>Liquor in the Neck to ſwell ſo much by <lb></lb>degrees, that at length it divers times ran <pb xlink:href="013/01/219.jpg" pagenum="189"></pb>over at the top: by which means, we <lb></lb>were hindred from being able to diſcern <lb></lb>upon the letting in of the Air, how much <lb></lb>the ſubſidence of the Oyl below the firſt <lb></lb>mark was due to the receſs of the bub<lb></lb>bles. </s></p><p type="main"> <s>Having likewiſe a minde to try whe<lb></lb>ther as ſtrong a ſolution of Salt of Tartar <lb></lb>in fair Water as could be made (we ha<lb></lb>ving then no Oyl of Tartar <emph type="italics"></emph>per deliqui<lb></lb>um<emph.end type="italics"></emph.end> at hand) though it be accounted, <lb></lb>Quick-ſilver excepted, the heavieſt of <lb></lb>Liquors would afford us any bubbles; we <lb></lb>put in a Glaſs Egge full of it at the ſame <lb></lb>time, with other Liquors, and found that <lb></lb>they did long yield ſtore of bubbles be<lb></lb>fore any diſcovered themſelves in the <lb></lb>Liquor of Tartar; and having purſued <lb></lb>the Experiment, it appear'd, That of all <lb></lb>the Liquors we made tryal of, this afford<lb></lb>ed the feweſt and the ſmalleſt Bubbles. </s></p><p type="main"> <s>Spirit of Vinager being try'd after the <lb></lb>ſame manner, exhibited a moderate num<lb></lb>ber of bubbles, but ſcarce any thing elſe <lb></lb>worth the mentioning. </s></p><p type="main"> <s>Nor could we in red Wine, try'd in a <lb></lb>Glaſs Egge, take notice of any thing ve<lb></lb>ry obſervable. </s> <s>For though upon the ex<lb></lb>ſuction of the Air the bubbles aſcended <pb xlink:href="013/01/220.jpg" pagenum="190"></pb>in this Liquor, as it were in ſholes, <lb></lb>and ſhifted places among themſelves in <lb></lb>their aſcent; yet the Intumeſcence of the <lb></lb>whole bulk of the Liquor was ſcarce at all <lb></lb>ſenſible, the bubbles moſt commonly <lb></lb>breaking very ſoon after their arrival at <lb></lb>the top, where during their ſtay, they <lb></lb>compoſ'd a kinde of ſhallow froth, which <lb></lb>alone appear'd higher in the Neck of the <lb></lb>Glaſs, then was the Wine when it was <lb></lb>firſt let down. </s> <s>Neither yet did Milk, con<lb></lb>vey'd into our Pneumatical Veſſel, pre<lb></lb>ſent us with any thing memorable, ſave <lb></lb>that (as it ſeem'd by reaſon of ſome un<lb></lb>ctuouſneſs of the Liquor) the bubbles <lb></lb>not eaſily breaking at the top, and thruſt<lb></lb>ing up one another made the intumeſcence <lb></lb>appear much greater then that of common <lb></lb>Water. </s></p><p type="main"> <s>We likewiſe convey'd Hens Eggs into <lb></lb>the Receiver, but, after the exſuction of <lb></lb>the Air, took them out whole again. </s> <s>That <lb></lb>which invited us to put them in, was, That <lb></lb>(as perhaps we mention in other Papers) <lb></lb>we had among other Experiments of <lb></lb>cold, made Eggs burſt, by freezing them <lb></lb>within doors with Snow and Salt: The <lb></lb>Ice, into which the aqueous parts of the <lb></lb>Egge were turned by the cold, ſo diſtend-<pb xlink:href="013/01/221.jpg" pagenum="191"></pb>ing (probably by reaſon of the numerous <lb></lb>bubbles wont to be obſervable in Ice) the <lb></lb>outward parts of the Egge, that it uſually <lb></lb>crack'd the ſhell, though the inner Mem<lb></lb>brane that involv'd the ſeveral Liquors <lb></lb>of the Egge, becauſe it would ſtretch <lb></lb>and yield, remain d unbroken, And here<lb></lb>upon we imagin'd that in our Engine it <lb></lb>might appear whether or no there were <lb></lb>any conſiderable Spring, either in any of <lb></lb>the Liquors, or in any other more ſpiri<lb></lb>tuous ſubſtance included in the Egge. </s></p><p type="main"> <s>We took alſo ſome Spirit of Urine, <lb></lb>careleſly enough deflegmed, and put it in<lb></lb>to the ſame Glaſs (firſt carefully ſcowr'd <lb></lb>and cleanſ'd) wherein we had put the Oyl<lb></lb>olive above mention'd: We took alſo an<lb></lb>other Glaſs, differing from a Glaſs Egge, <lb></lb>onely in that its bottom was ſlat, and fill'd <lb></lb>it up to about 2/3 of the Neck (which was <lb></lb>wider then that of the Egge) with rectifi<lb></lb>ed Spirit of Wine. </s></p><p type="main"> <s>We took alſo another Glaſs Egge, and <lb></lb>having fill'd it with common Water till it <lb></lb>reach'd to the middle of the Neck, we <lb></lb>pour'd to it of the ſame Spirit of Wine, <lb></lb>till it reach'd about an Inch higher. </s></p><p type="main"> <s>Theſe three Glaſſes having marks ſet <lb></lb>on them, over againſt the edges of the <pb xlink:href="013/01/222.jpg" pagenum="192"></pb>contain'd Liquors were put into the Re<lb></lb>ceiver, and that beginning to be evacua<lb></lb>ted, the bubbles in all the three Liquors <lb></lb>began to appear. </s> <s>The mixture of the <lb></lb>Spirit of Wine and Water diſcloſ'd a <lb></lb>great ſtore of bubbles, eſpecially towards <lb></lb>the top; but ſcarce afforded us any thing <lb></lb>worth remem bring. </s> <s>The Spirit of Urine <lb></lb>appear'd to ſwell near an Inch and an half <lb></lb>above the mark; and beſides that, ſent <lb></lb>forth ſtore of bubbles, which made a <lb></lb>kinde of froth at the upper part of it. </s> <s>And <lb></lb>above that ſpume there appear'd eight or <lb></lb>ten great bubbles one above another, in a <lb></lb>very decent order, each of them conſtitu<lb></lb>ting, as it were, a Cylinder of about half <lb></lb>an Inch high, and as broad as the internal <lb></lb>cavity of the Neck: So that all the upper <lb></lb>part of the Neck (for theſe bubbles reach'd <lb></lb>to the top) ſeem'd to be divided into al<lb></lb>moſt equal parts, by certain Diaphrag<lb></lb>mes, conſiſting of the coats of the bub<lb></lb>bles, whoſe edges appear'd like ſo many <lb></lb>Rings ſuſpended one above another. </s></p><p type="main"> <s>In the Spirit of Wine there did ariſe a <lb></lb>great multitude of bubbles, even till <lb></lb>wearineſs did make us give over the Ex<lb></lb>periment. </s> <s>And in theſe bubbles two or <lb></lb>three things were remarkable; as firſt, <pb xlink:href="013/01/223.jpg" pagenum="193"></pb>That they aſcended with a very notable <lb></lb>celerity: Next, That being arriv'd at the <lb></lb>top, they made no ſtay there, and yet, <lb></lb>notwithſtanding the great thinneſs and <lb></lb>ſpitituouſneſs of the Liquor, did, before <lb></lb>they broke, lift up the upper ſurface of <lb></lb>it, and for a moment or two form thereof <lb></lb>a thin film or skin which appear'd protu<lb></lb>berant above the reſt of the ſuperficies <lb></lb>like a ſmall Hemiſphere. </s> <s>Thirdly, That <lb></lb>they aſcended ſtraight up, whereas thoſe <lb></lb>produc'd at the lower part of the Veſſel, <lb></lb>containing the mixture of the Water and <lb></lb>Spirit of Wine, aſcended with a waver<lb></lb>ing or wrigling motion, whereby they <lb></lb>deſcrib'd an indented Line. </s> <s>Laſtly, It <lb></lb>was obſervable in the Spirit of Wine (and <lb></lb>we took notice of the like in the Oyl of <lb></lb>Turpentine lately mention'd) that not <lb></lb>onely the bubbles ſeem'd to riſe from cer<lb></lb>tain determinate places at the bottom of <lb></lb>the Glaſs, but that in their aſcenſion they <lb></lb>kept an almoſt equal diſtance from each <lb></lb>other, and follow'd one another in a cer<lb></lb>tain order, whereby they ſeem'd part of <lb></lb>ſmall Bracelets, conſiſting of equally lit<lb></lb>tle incontiguous Beads: the lower end of <lb></lb>each Bracelet, being as it were, faſten'd to <lb></lb>a certain point at the bottom of the Glaſs. </s></p><pb xlink:href="013/01/224.jpg" pagenum="194"></pb><p type="main"> <s>The Air being ſparingly let into the <lb></lb>Receiver, the great bubbles formerly <lb></lb>mention'd as incumbent upon one ano<lb></lb>ther, in that Glaſs that contain'd the Spi<lb></lb>rit of Urine, were by orderly degrees <lb></lb>leſſen'd, till at length they wholly ſubſi<lb></lb>ded, notwithſtanding the receſs of ſo ma<lb></lb>ny bubbles as broke on the top of the <lb></lb>Spirit of Urine, during all the time of the <lb></lb>Experiment; yet it ſcarcely appear'd at all <lb></lb>to be ſunk below the mark: Nor did the <lb></lb>mixture of Spirit of Wine and Water <lb></lb>conſiderably ſubſide. </s> <s>But that is no<lb></lb>thing to what we obſerv'd in the Spirit <lb></lb>of Wine, for not onely it conſpicuouſly <lb></lb>expanded it ſelf in the Neck of the <lb></lb>Veſſel that contain'd it, notwithſtand<lb></lb>ing the largeneſs of it; and that the <lb></lb>bubbles were about to break at the <lb></lb>top of it almoſt aſſoon as they arriv'd <lb></lb>there: but upon the re-admiſſion of <lb></lb>the external Air, the Spirit of Wine <lb></lb>retain'd its newly acquired expanſion. <lb></lb></s> <s>And though we let it alone for near <lb></lb>an hour together, in expectation that it <lb></lb>might ſubſide; yet when we took it <lb></lb>out, we found it ſtill ſwell'd between a <lb></lb>quarter and half an Inch above the <lb></lb>mark; and although it was not eaſily <pb xlink:href="013/01/225.jpg" pagenum="195"></pb>imaginable how this <emph type="italics"></emph>Phænomenon<emph.end type="italics"></emph.end> could <lb></lb>proceed from any miſtake in trying <lb></lb>the Experiment, yet the ſtrangeneſſe <lb></lb>of it invited me to repeat it with freſh <lb></lb>Spirit of Wine; which, ſwelling in the <lb></lb>Neck as formerly, I left all Night in <lb></lb>the Receiver, allowing free acceſs to the <lb></lb>external Air at the Stop-cock, and the <lb></lb>next day found it ſtill expanded as be<lb></lb>fore, ſave that it ſeem'd a little lower: <lb></lb>which decrement perhaps proceeded from <lb></lb>the avolation of ſome of the fugitive <lb></lb>parts of ſo volatile a Liquor. </s> <s>And for <lb></lb>better ſatisfaction having taken out the <lb></lb>Glaſs, and conſider'd it in the open Air, <lb></lb>and at a Window, I could not finde that <lb></lb>there was any remaining Bubbles that <lb></lb>could occaſion the perſevering and ad<lb></lb>mir'd expanſion. </s></p><p type="main"> <s>BEing deſirous to diſcover what diffe<lb></lb><arrow.to.target n="marg32"></arrow.to.target><lb></lb>rence there might be as to gravity and <lb></lb>levity, between Air expanded under Wa<lb></lb>ter, and it ſelfe before ſuch expanſion; we <lb></lb>took two very ſmall Viols, ſuch as Chy<lb></lb>mical Eſſences (as they call them) are wont <lb></lb>to be kept in, and of the ſize and ſhape ex<lb></lb>preſſed by the 8<emph type="sup"></emph>th<emph.end type="sup"></emph.end> Figure: into one of theſe <pb xlink:href="013/01/226.jpg" pagenum="196"></pb>we put ſo much of a certain ponderous <lb></lb>Mercurial mixture (hapning to be then at <lb></lb>hand) that the mouth being ſtopt with a <lb></lb>little ſoft Wax, the Glaſs would juſt ſink <lb></lb>in Water and no more; this we let fall to <lb></lb>the bottom of a wide-mouth'd Cryſtal <lb></lb>Jar, fill'd with about half a pint of com<lb></lb>mon Water, and into the ſame Veſſel we <lb></lb>ſunk the other Eſſence Glaſs unſtopp'd, <lb></lb>with as much Water in it as was more <lb></lb>then ſufficient to make it ſubſide. </s> <s>Both <lb></lb>theſe ſunk with their mouthes downward, <lb></lb>the former being about three quarters full <lb></lb>of Air, the latter containing in it a bub<lb></lb>ble of Air that was gheſſ'd to be of the <lb></lb>bigneſs of half a Pea: This done, the <lb></lb>wide-mouth'd Glaſs was let down into <lb></lb>the Receiver, and the way of imploy<lb></lb>ing the Engine was carefully made uſe <lb></lb>of. </s></p><p type="margin"> <s><margin.target id="marg32"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 25.</s></p><p type="main"> <s>The ſucceſs was, That having drawn <lb></lb>out a pretty quantity of Air, the bubbles <lb></lb>began to diſcloſe themſelves in the Wa<lb></lb>ter, as in the former Experiments; and <lb></lb>though for a good while after the bubbles <lb></lb>aſcended in ſwarms from the lower parts <lb></lb>of the Water, and haſtily broke at the <lb></lb>top; yet we proſecuted the Experiment <lb></lb>ſo long without ſeeing any effect wrought <pb xlink:href="013/01/227.jpg" pagenum="197"></pb>upon the Eſſence: Bottles, that we began <lb></lb>to diſpair of ſeeing either of them riſe, but <lb></lb>continuing to ply the Pump, that little <lb></lb>Glaſs, whoſe mouth was open'd, came to <lb></lb>the top of the Water, being, as it were, <lb></lb>boy'd up thither by a great number of <lb></lb>bubbles that had faſtned themſelves to <lb></lb>the ſides of it; ſwimming thus with the <lb></lb>mouth downward, we could eaſily per<lb></lb>ceive that the internal Air above men<lb></lb>tion'd had much delated it ſelf, and there<lb></lb>by ſeem'd to have contributed to the e<lb></lb>merging of the Glaſs, which remain'd <lb></lb>floating, notwithſtanding the breaking <lb></lb>and vaniſhing of moſt of the contiguous <lb></lb>bubbles: being hereby incouraged to per<lb></lb>ſiſt in pumping, we obſerved with ſome <lb></lb>pleaſure, that at each time we turn'd the <lb></lb>Key, the Air in the little Glaſs did mani<lb></lb>feſtly expand it ſelf and thruſt out the wa<lb></lb>ter, generally retaining a very protuberant <lb></lb>ſurface where it was contiguous to the re<lb></lb>maining Water. </s> <s>And when after divers <lb></lb>exſuctions of the Air in the Receiver, <lb></lb>that in the little Viol ſo dilated it ſelf as <lb></lb>to expel almoſt all the Water, it turn'd <lb></lb>up its mouth towards the ſurface of the <lb></lb>Water in the Jar, and there deliver'd a <lb></lb>large bubble, and then relapſed into its <pb xlink:href="013/01/228.jpg" pagenum="198"></pb>formér floating poſture: And this Expe<lb></lb>riment taught us, among other things, <lb></lb>that it was a work of more time and la<lb></lb>bor then we imagin'd, to exhauſt our En<lb></lb>gine as much as it may be exhauſted: for <lb></lb>although before the emerging of the ſmall <lb></lb>Viol, we did (as has been touch'd alrea<lb></lb>dy) think we had very conſiderably em<lb></lb>ptyed the Receiver, becauſe there ſeem'd <lb></lb>to come out but very little or almoſt <lb></lb>no ſenſible Air at each exſuction into <lb></lb>and out of the Cylinder; yet after<lb></lb>wards, at each drawing down the Suc<lb></lb>ker, the Air included in the Viol did <lb></lb>manifeſtly dilate it ſelf, ſo long, that <lb></lb>it did no leſs then nine times turn its <lb></lb>mouth upwards, and diſcharge a bub<lb></lb>ble by conjecture about the bigneſs of <lb></lb>a Pea, after the manner newly recited. <lb></lb></s> <s>But as for that Violl which had the <lb></lb>weight in it, it roſe not at all. </s> <s>So <lb></lb>that being not able by quick pumping <lb></lb>to gain another bubble from the Air <lb></lb>in the ſwimming Glaſs, which proceed<lb></lb>ed from ſome ſmall leak in the Veſſel, <lb></lb>though it held in this Experiment more <lb></lb>ſtanch then was uſual, we thought fit <lb></lb>to let in leaſurely the Air from with<lb></lb>out, upon whoſe admiſſion that with-<pb xlink:href="013/01/229.jpg" pagenum="199"></pb>in the Viol ſhrinking into a very nar<lb></lb>row compaſs, the Glaſs did, as we expe<lb></lb>cted, fall down to the bottom of the <lb></lb>Jar. </s></p><p type="main"> <s>But being deſirous before we proceed<lb></lb>ed to any new. </s> <s>Experiment, to try once <lb></lb>more whether the little Glaſs that had <lb></lb>the weight in it might not alſo be raiſ'd. <lb></lb></s> <s>After we had ſuffer'd the Engine to re<lb></lb>main cloſ'd as it was, for five or ſix <lb></lb>hours, the Pump was again ply'd with <lb></lb>ſo much obſtinacy, that not onely a<lb></lb>bout the upper part of the Jar there ap<lb></lb>pear'd a good number of bubbles (but <lb></lb>very much ſmaller then thoſe we ſaw <lb></lb>the firſt time) but afterwards there <lb></lb>came from the bottom of the Jar, bub<lb></lb>bles about the bigneſs of ſmal Peas: which <lb></lb>the Pump being ſtill kept going, fol<lb></lb>low'd one another, to the number of forty, <lb></lb>coming from the ſtopp'd Violl; whoſe <lb></lb>mouth, it ſeems, had not been ſhut ſo <lb></lb>ſtrongly and cloſely, but that the included <lb></lb>Air, dilating it ſelf by its own ſpring, made <lb></lb>itſelf ſome little paſſage betwixt the Wall <lb></lb>and the Glaſs, and got away in theſe bub<lb></lb>bles; after which, the unſtopp'd Glaſs be<lb></lb>gan to float again, the Air ſhut up in it <pb xlink:href="013/01/230.jpg" pagenum="200"></pb>being manifeſtly ſo dilated as to expel a <lb></lb>good part of the Water, but not ſo much <lb></lb>as to break quite thorow. </s> <s>And at length, <lb></lb>when our expectation of it was almoſt ti<lb></lb>red out, the heavier of the two Viols be<lb></lb>gan to come aloft, and immediately to <lb></lb>ſubſide again, which appear'd to be oc<lb></lb>caſion'd by the Air within it, whoſe bulk <lb></lb>and ſpring being weaken'd by the receſs <lb></lb>of the forty bubbles before-mention'd, it <lb></lb>was no longer able, as formerly, to break <lb></lb>forcibly through the incumbent Water; <lb></lb>but forming a bubble at the mouth of the <lb></lb>Glaſs, boyed it up towards the top, and <lb></lb>there getting away, left it to ſink again <lb></lb>till the preſſure of the Air in the Recei<lb></lb>ver being further taken off, the Air in the <lb></lb>Viol was permitted to expand it ſelf fur<lb></lb>ther, and to create another bubble, by <lb></lb>which it was again for a while carried up. <lb></lb></s> <s>And it was remarkable, that though after <lb></lb>having emptyed the Receiver as far as <lb></lb>well we could, we ceaſ'd from pumping; <lb></lb>yet the Veſſel continuing more ſtanch <lb></lb>then it was wont, this aſcent and fall of <lb></lb>the Viol was repeated to the ninth time; <lb></lb>the included Air, by reaſon of the ſmal<lb></lb>neſs of the vent at which it muſt paſs out, <lb></lb>being not able to get away otherwiſe then <pb xlink:href="013/01/231.jpg" pagenum="201"></pb>little by little; and conſequently, in divers <lb></lb>ſuch parcels as were able to conſtitute <lb></lb>bubbles, each of them big enough to <lb></lb>raiſe the Viol and keep it aloft until the <lb></lb>avolation of that bubble. </s> <s>Whereby it <lb></lb>may appear, that the grand rule in <emph type="italics"></emph>Hy<lb></lb>droſtaticks,<emph.end type="italics"></emph.end> That a Body will ſwim in the <lb></lb>Water, in caſe it be lighter then as much <lb></lb>of that Water that equals it in bulk, will <lb></lb>hold likewiſe when the preſſure of the At<lb></lb>moſphere is in very great meaſure, if not <lb></lb>when it is totally taken off from the Li<lb></lb>quor and the Body: though it were worth <lb></lb>inquiring what it is that ſo plentifully <lb></lb>concurs to fill the bubbles made in our <lb></lb>Experiment by the ſo much expanded <lb></lb>Air, for to ſay with the old Peripatetick <lb></lb>Schools, That the Air, in Rarefaction, <lb></lb>may acquire a new extent, without the <lb></lb>admiſſion of any new ſubſtance, would <lb></lb>be an account of the <emph type="italics"></emph>Phænomenon<emph.end type="italics"></emph.end> very <lb></lb>much out of date, and which, I ſuppoſe, <lb></lb>our Modern Naturaliſts would neither <lb></lb>give, nor acquieſs in. </s></p><p type="main"> <s>I know not whether it may be requiſite <lb></lb>to adde, that in this Experiment, as in <lb></lb>the former, the outward Air being let in <lb></lb>did ſoon precipitate the floating Viol. </s> <s>But <lb></lb>I think it will not be amiſs to note, that <pb xlink:href="013/01/232.jpg" pagenum="202"></pb>(congruouſly to what hath been above <lb></lb>recorded of the vaſt expanſion of the Air) <lb></lb>the Water which in the heavier Viol ſuc<lb></lb>ceeded in the room of thoſe forty odde, if <lb></lb>not fifty great bubbles of Air, which at <lb></lb>ſeveral times got out of it, amounted but <lb></lb>to a very inconſiderable bigneſs. </s></p><p type="main"> <s>IT having been obſerv'd by thoſe that <lb></lb><arrow.to.target n="marg33"></arrow.to.target><lb></lb>have conſider'd what belongs to <emph type="italics"></emph>Pendu<lb></lb>lums<emph.end type="italics"></emph.end> (a Speculation that may, in my <lb></lb>poor judgement, be highly uſeful to the <lb></lb>Naturaliſts) that their Vibrations are <lb></lb>more ſlowly made, and that their moti<lb></lb>on laſts leſs in a thicker, then in a thinner <lb></lb>Medium: We thought it not amiſs to <lb></lb>try if a <emph type="italics"></emph>Pendulum<emph.end type="italics"></emph.end> would ſwing faſter, or <lb></lb>continue ſwinging longer in our Receiver, <lb></lb>in caſe of the exſuction of the Air, then <lb></lb>otherwiſe. </s> <s>Wherefore we took a couple <lb></lb>of round and poliſh'd <emph type="italics"></emph>Pendulums<emph.end type="italics"></emph.end> of Iron <lb></lb>or Steel, of equal bigneſs, as near as we <lb></lb>could get the Artificer to make them, and <lb></lb>weighing each of them twenty Dragmes, <lb></lb>wanting as many Grains. </s> <s>One of theſe <lb></lb>we ſuſpended in the cavity of the Recei<lb></lb>ver by a very ſlender ſilken ſtring, of a<lb></lb>bout ſeven Inches and a half in length <pb xlink:href="013/01/233.jpg" pagenum="203"></pb>from the cover of the Receiver to which <lb></lb>it was faſten'd. </s> <s>Then (by inclining the <lb></lb>Engine) we made the <emph type="italics"></emph>Pendulum<emph.end type="italics"></emph.end> ſwing too <lb></lb>and fro in it, and deſcrib'd as long Arches <lb></lb>as in the capacity of ſo brittle a Veſſel we <lb></lb>thought ſafe and convenient. </s> <s>And one of <lb></lb>the Aſſiſtants telling the recurſions of the <lb></lb>other <emph type="italics"></emph>Pendulum<emph.end type="italics"></emph.end> hanging in the free Air, <lb></lb>by a ſtring of about the ſame length, we <lb></lb>ſhorten'd and lengthen'd this other <emph type="italics"></emph>Pen<lb></lb>dulum,<emph.end type="italics"></emph.end> till it appear'd to keep the ſame <lb></lb>pace in its Vibrations, with that ſhut up in <lb></lb>the Receiver. </s> <s>Then having carefully <lb></lb>drawn away the Air, we did again ſet the <lb></lb><emph type="italics"></emph>Pendulum<emph.end type="italics"></emph.end> in the Receiver a vibrating; <lb></lb>and giving the other <emph type="italics"></emph>Pendulum<emph.end type="italics"></emph.end> ſuch a mo<lb></lb>tion as made it deſcribe an Arch, accord<lb></lb>ing to ones gheſs, equal to that of the in<lb></lb>cluded <emph type="italics"></emph>Pendulum;<emph.end type="italics"></emph.end> we reckon'd, one of <lb></lb>us, the Recurſions of that <emph type="italics"></emph>Pendulum<emph.end type="italics"></emph.end> which <lb></lb>was ſwinging within the Receiver; and <lb></lb>another of us that which was moving in <lb></lb>(that which one would think a much more <lb></lb>reſiſting <emph type="italics"></emph>medinm<emph.end type="italics"></emph.end>) the Air. </s> <s>But once, one <lb></lb>of us reckon'd near two and twenty Re<lb></lb>curſions of the included <emph type="italics"></emph>Pendulum,<emph.end type="italics"></emph.end> whilſt <lb></lb>the other reckon'd but twenty of the <emph type="italics"></emph>Pen<lb></lb>dulum<emph.end type="italics"></emph.end> that vibrated without. </s> <s>And an<lb></lb>other time alſo, the former of theſe <emph type="italics"></emph>Pen-<emph.end type="italics"></emph.end><pb xlink:href="013/01/234.jpg" pagenum="204"></pb><emph type="italics"></emph>dula<emph.end type="italics"></emph.end> was reckon'd to have made one and <lb></lb>twenty Recurſions, wherein the other <lb></lb>made but twenty: Yet this Experiment <lb></lb>ſeem'd to teach us little, ſave that the dif<lb></lb>ference betwixt the motion of ſuch a <emph type="italics"></emph>Pen<lb></lb>dulum<emph.end type="italics"></emph.end> in the common Air, and in one ex<lb></lb>ceedingly rarified, is ſcarce ſenſible in <lb></lb>Veſſels no bigger then our Receiver; e<lb></lb>ſpecially ſince though during this Expe<lb></lb>riment it held very well, yet we could <lb></lb>not ſuppoſe it to be altogether devoid of <lb></lb>Air. </s> <s>We obſerv'd alſo, that when the <lb></lb>Receiver was full of Air, the included <lb></lb><emph type="italics"></emph>Pendulum<emph.end type="italics"></emph.end> continu'd its Recurſions about <lb></lb>fifteen minutes (or a quarter of an hour) <lb></lb>before it left off ſwinging; and that after <lb></lb>the exſuction of the Air, the Vibration <lb></lb>of the ſame <emph type="italics"></emph>Pendulum<emph.end type="italics"></emph.end> (being freſh put in<lb></lb>to motion) appear'd not (by a minutes <lb></lb>Watch) to laſt ſenſibly longer. </s> <s>So that <lb></lb>the event of this Experiment being other <lb></lb>then we expected, ſcarce afforded us any <lb></lb>other ſatisfaction, then that of our not <lb></lb>having omitted to try it. </s> <s>And whether <lb></lb>in caſe the tryal be made with a <emph type="italics"></emph>Pendulum<emph.end type="italics"></emph.end><lb></lb>much leſs diſproportionate to the Air then <lb></lb>Steel is, the event will much better an<lb></lb>ſwer expectation, experience may be con<lb></lb>ſulted. </s></p><pb xlink:href="013/01/235.jpg" pagenum="205"></pb><p type="margin"> <s><margin.target id="marg33"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 26.</s></p><p type="main"> <s>THat the Air is the medium whereby <lb></lb>ſounds are convey'd to the Ear, has <lb></lb><arrow.to.target n="marg34"></arrow.to.target><lb></lb>been for many Ages, and is yet the com<lb></lb>mon Doctrine of the Schools. </s> <s>But this <lb></lb>Received Opinion has been of late op<lb></lb>poſ'd by ſome Philoſophers upon the ac<lb></lb>count of an Experiment made by the <lb></lb>Induſtrious <emph type="italics"></emph>Kircher,<emph.end type="italics"></emph.end> and other Learned <lb></lb>Men, who have (as they aſſure us) ob<lb></lb>ſerv'd, That if a Bell, with a Steel Clap<lb></lb>per, be ſo faſten'd to the inſide of a Tube, <lb></lb>that upon the making the Experiment <emph type="italics"></emph>De <lb></lb>Vacuo<emph.end type="italics"></emph.end> with that Tube, the Bell remain'd <lb></lb>ſuſpended in the deſerted ſpace at the up<lb></lb>per end of the Tube: And if alſo a vi<lb></lb>gorous Load-ſtone be apply'd on the out<lb></lb>ſide of the Tube to the Bell, it will at<lb></lb>tract the Clapper, which upon the Remo<lb></lb>val of the Load-ſtone falling back, will <lb></lb>ſtrike againſt the oppoſite ſide of the <lb></lb>Bell, and thereby produce a very audible <lb></lb>ſound, whence divers have concluded, <lb></lb>That 'tis not the Air, but ſome more ſub<lb></lb>tle Body that is the medium of ſounds. <lb></lb></s> <s>But becauſe we conceiv'd that, to invali<lb></lb>date ſuch a conſequence from this ingeni<lb></lb>ous Experiment (though the moſt lucife-<pb xlink:href="013/01/236.jpg" pagenum="206"></pb>rous, that could well be made without <lb></lb>ſome ſuch Engine as ours) ſome things <lb></lb>might be ſpeciouſly enough alleadg'd; we <lb></lb>thought fit to make a tryal or two, in or<lb></lb>der to the Diſcovery of what the Air does <lb></lb>in conveying of ſounds, reſerving divers <lb></lb>other Experiments tryable in our Engine <lb></lb>concerning ſounds, till we can obtain more <lb></lb>leaſure to proſecute them. </s> <s>Conceiving it <lb></lb>then the beſt way to make our tryal with <lb></lb>ſuch a noiſe as might not be loud enough <lb></lb>to make it difficult to diſcern ſlighter va<lb></lb>riations in it, but rather might be, both <lb></lb>laſting, that we might take notice by what <lb></lb>degrees it decreaſ'd; and ſo ſmall, that <lb></lb>it could not grow much weaker with<lb></lb>out becoming imperceptible. </s> <s>We took <lb></lb>a Watch, whoſe Caſe we open'd, that <lb></lb>the contain'd Air might have free egreſs <lb></lb>into that of the Receiver. </s> <s>And this Watch <lb></lb>was ſuſpended in the cavity of the Veſſel <lb></lb>onely by a Pack-thred, as the unlikelieſt <lb></lb>thing to convey a ſound to the top of the <lb></lb>Receiver: And then cloſing up the Veſ<lb></lb>ſel with melted Plaiſter, we liſten'd near <lb></lb>the ſides of it, and plainly enough heard <lb></lb>the noiſe made by the ballance. </s> <s>Thoſe al<lb></lb>ſo of us, that watch'd for that Circum<lb></lb>ſtance, obſerv'd, that the noiſe ſeem'd to <pb xlink:href="013/01/237.jpg" pagenum="207"></pb>come directly in a ſtraight Line from the <lb></lb>Watch unto the Ear. </s> <s>And it was obſerva<lb></lb>ble to this purpoſe, that we found a mani<lb></lb>feſt diſparity of noiſe, by holding our Ears <lb></lb>near the ſides of the Receiver, and near the <lb></lb>Cover of it: which difference ſeem'd to <lb></lb>proceed from that of the Texture of the <lb></lb>Glaſs, from the ſtructure of the cover (and <lb></lb>of the Cement) through which the ſound <lb></lb>was propagated from the Watch to the <lb></lb>Ear. </s> <s>But let us proſecute our Experiment. <lb></lb></s> <s>The Pump after this being imployd, it <lb></lb>ſeemd that from time to time the ſound <lb></lb>grew fainter and fainter; ſo that when the <lb></lb>Rec iver was empty'd as much as it uſ'd <lb></lb>to be for the foregoing Experiments, nei<lb></lb>ther we, nor ſome ſtrangers that chanc'd <lb></lb>to be then in the room, could, by applying <lb></lb>our Ears to the very ſides, hear any noiſe <lb></lb>from within; though we could eaſily per<lb></lb>ceive that by the moving of the hand <lb></lb>which mark'd the ſecond minutes, and by <lb></lb>that of the ballance, that the Watch nei<lb></lb>ther ſtood ſtil, nor remarkably varied from <lb></lb>its wonted motion. </s> <s>And to ſatisfie our <lb></lb>ſelvs further that it was indeed the abſence <lb></lb>of the Air about the Watch that hinder'd <lb></lb>us from hearing it, we let in the external <lb></lb>Air at the Stop-cock, and then though we <pb xlink:href="013/01/238.jpg" pagenum="208"></pb>turn'd the Key and ſtopt the Valve, yet we <lb></lb>could plainly hear the noiſe made by the <lb></lb>ballance, though we held our Ears ſome<lb></lb>times at two Foot diſtance from the out<lb></lb>ſide of the Receiver. </s> <s>And this Experi<lb></lb>ment being reiterated in another place, <lb></lb>ſucceded after the like manner. </s> <s>Which <lb></lb>ſeems to prove, that whether or no the <lb></lb>Air be the onely, it is at leaſt, the princi<lb></lb>pal medium of Sounds. </s> <s>And by the way <lb></lb>it is very well worth noting, that in a Veſ<lb></lb>ſel ſo well cloſ'd as our Receiver, ſo weak <lb></lb>a pulſe as that of the ballance of a Watch <lb></lb>ſhould propagate a motion to the Ear in a <lb></lb>Phiſically ſtraight Line, notwithſtanding <lb></lb>the interpoſition of ſo cloſe a Body as <lb></lb>Glaſs, eſpecially Glaſs of ſuch thickneſs <lb></lb>as that of our Receiver; ſince by this it <lb></lb>ſeems that the air impriſon'd in the Glaſs, <lb></lb>muſt, by the motion of the ballance, be <lb></lb>made to beat againſt the concave part of <lb></lb>the Receiver, ſtrongly enough to make <lb></lb>its convex part beat upon the contiguous <lb></lb>Air, and ſo propagate the motion to the <lb></lb>Liſtners ears. </s> <s>I know this cannot but <lb></lb>ſeem ſtrange to thoſe, who, with an emi<lb></lb>nent Modern Philoſopher, will not allow <lb></lb>that a Sound, made in the cavity of a <lb></lb>Room, or other place ſo cloſ'd, that there <pb xlink:href="013/01/239.jpg" pagenum="209"></pb>is no intercourſe betwixt the external and <lb></lb>internal Air, can be heard by thoſe with<lb></lb>out, unleſs the ſounding Body do imme<lb></lb>diately ſtrike againſt ſome part of the in<lb></lb>cloſing Body. </s> <s>But not having now time <lb></lb>to handle Controverſies, we ſhall onely <lb></lb>annex, That after the foregoing Experi<lb></lb>ment, we took a Bell of about two Inches <lb></lb>in Diameter at the bottom, which was <lb></lb>ſupported in the midſt of the cavity of <lb></lb>the Receiver by a bent ſtick, which by <lb></lb>reaſon of its Spring preſſ'd with its two <lb></lb>ends againſt the oppoſite parts of the in<lb></lb>ſide of the Veſſel: in which, when it was <lb></lb>cloſ'd up, we obſerv'd that the Bell ſeem'd <lb></lb>to ſound more dead then it did when juſt <lb></lb>before it ſounded in the open Air. </s> <s>And <lb></lb>yet, when afterwards we had as formerly <lb></lb>emptyed the Receiver, we could not diſ<lb></lb>cern any conſiderable change (for ſome <lb></lb>ſaid they obſerv'd a ſmall one) in the loud<lb></lb>neſs of the ſound, whereby it ſeem'd that <lb></lb>though the Air be the principal medium <lb></lb>of ſound, yet either a more ſubtle mat<lb></lb>ter may be alſo a medium of it, or elſe an <lb></lb>ambient Body that contains but very <lb></lb>few particles of Air, in compariſon of <lb></lb>thoſe it is eaſily capable of, is ſufficient <lb></lb>for that purpoſe. </s> <s>And this, among o-<pb xlink:href="013/01/240.jpg" pagenum="210"></pb>ther things, invited us to conſider, whether <lb></lb>in the above-mention'd Experiment made <lb></lb>with the Bell and the Load-ſtone, there <lb></lb>might not in the deſerted part of the Tube <lb></lb>remain Air enough to produce a ſound: <lb></lb>ſince the Tubes for the Experiment <emph type="italics"></emph>De <lb></lb>Vacuo<emph.end type="italics"></emph.end> (not to mention the uſual thin<lb></lb>neſs of the Glaſs) being ſeldom made <lb></lb>greater then is requiſite, a little Air might <lb></lb>bear a not inconſiderable proportion to <lb></lb>the deſerted ſpace. </s> <s>And that alſo, in the <lb></lb>Experiment <emph type="italics"></emph>De Vacuo,<emph.end type="italics"></emph.end> as it is wont to be <lb></lb>made, there is generally ſome little Air <lb></lb>that gets in from without, or at leaſt ſtore <lb></lb>of bubbles that ariſe from the Body of <lb></lb>the Quick-ſilver, or other Liquor it ſelf, <lb></lb>Obſervations heedfully made have fre<lb></lb>quently informed us: And it may alſo <lb></lb>appear, by what has been formerly deli<lb></lb>vered concerning the <emph type="italics"></emph>Torricellian<emph.end type="italics"></emph.end> Experi<lb></lb>ment. </s></p><p type="margin"> <s><margin.target id="marg34"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 27.</s></p><p type="main"> <s>On the occaſion of this Experiment <lb></lb>concerning ſounds, we may adde in this <lb></lb>place, That when we try'd the Experiment <lb></lb>formerly mention'd, of firing Gun-pow<lb></lb>der with a Piſtol in our evacuated Recei<lb></lb>ver, the noiſe made by the ſtriking of the <lb></lb>Flint againſt the Steel, was exceeding <lb></lb>languid in compariſon of what it would <pb xlink:href="013/01/241.jpg" pagenum="211"></pb>have been in the open Air. </s> <s>And on di<lb></lb>vers other occaſions it appear'd that the <lb></lb>ſounds created within our exhauſted <lb></lb>Glaſs, if they were not loſt before they <lb></lb>reach'd the Ear, ſeem'd at leaſt to arrive <lb></lb>there very much weaken'd. </s> <s>We intended <lb></lb>to try whether or no the Wire-ſtring of an <lb></lb>Inſtrument ſhut up into our Receiver, <lb></lb>would, when the ambient Air was ſuck'd <lb></lb>out, at all tremble, if in another Inſtrument <lb></lb>held cloſe to it, but without the Receiver <lb></lb>a ſtring tun'd (as Muſicians ſpeak, how <lb></lb>properly I now examine not) to an Uniſon <lb></lb>with it, were briskly toucht, and ſet a Vi<lb></lb>brating. </s> <s>This, I ſay, we purpoſ'd to try <lb></lb>to ſee how the motion made in the Air <lb></lb>without, would be propagated through the <lb></lb>cavity of our evacuated Receiver. </s> <s>But <lb></lb>when the Inſtrument wherewith the tryal <lb></lb>was to be made came to be imploy'd, it <lb></lb>prov'd too big to go into the Pneumatical <lb></lb>Veſſel, and we have not now the conveni<lb></lb>ency to have a fitter made. </s></p><p type="main"> <s>We thought likewiſe to convey into <lb></lb>the Receiver a long and ſlender pair of <lb></lb>Bellows, made after the faſhion of thoſe <lb></lb>uſually employ'd to blow Organs, and fur<lb></lb>niſh'd with a ſmall Muſical inſtead of an <pb xlink:href="013/01/242.jpg" pagenum="212"></pb>ordinary Pipe. </s> <s>For we hop'd, that by <lb></lb>means of a ſtring faſtned to the upper <lb></lb>part of the Bellows, and to the moveable <lb></lb>ſtopple that makes a part of the Cover <lb></lb>of our Receiver, we ſhould, by frequent<lb></lb>ly turning round that ſtopple, and the an<lb></lb>nexed ſtring, after the manner already <lb></lb>often recited, be able to lift up and diſtend <lb></lb>the Bellows; and by the help of a com<lb></lb>petent weight faſten'd to the ſame upper <lb></lb>part of the Bellows, we ſhould likewiſe <lb></lb>be able, at pleaſure, to compreſs them: <lb></lb>and by conſequence, try whether that <lb></lb>ſubtler matter then Air (which, accord<lb></lb>ing to thoſe that deny a <emph type="italics"></emph>Vacuum,<emph.end type="italics"></emph.end> muſt be <lb></lb>ſuppoſ'd to fill the exhauſted Receiver) <lb></lb>would be able to produce a ſound in the <lb></lb>Muſical Pipe; or in a Pipe like that of or<lb></lb>dinary Bellows, to beget a Wind capable <lb></lb>to turn or ſet a moving ſome very light <lb></lb>matter, either ſhap'd like the Sails of a <lb></lb>Wind-Mill, or of ſome other conveni<lb></lb>ent form, and expoſ'd to its Orifice. </s> <s>This <lb></lb>Experiment, I ſay, we thought to make, <lb></lb>but have not yet actually made it for want <lb></lb>of an Artificer to make us ſuch a pair of <lb></lb>Bellows as it requires. </s></p><p type="main"> <s>We had thoughts alſo of trying whe<lb></lb>ther or no, as Sounds made by Bodies in <pb xlink:href="013/01/243.jpg" pagenum="213"></pb>our Receiver become much more languid <lb></lb>then ordinary, by reaſon of the want of <lb></lb>Air, ſo they would grow ſtronger, in caſe <lb></lb>there were an unuſual quantity of Air <lb></lb>crouded and ſhut up in the ſame Veſſel, <lb></lb>which may be done (though not without <lb></lb>ſome difficulty) by the help of the Pump, <lb></lb>provided the Cover and Stopple be ſo <lb></lb>firmly faſten'd (by binding and Cement, <lb></lb>or otherwiſe) to the Glaſs; and to each <lb></lb>other, that there be no danger of the <lb></lb>condenſ'd Airs blowing of either of them <lb></lb>away, or its breaking through the jun<lb></lb>ctures. </s> <s>Theſe thoughts, My Lord, as I <lb></lb>was ſaying, we entertain'd; but for want <lb></lb>of leaſure, as, of as good Receivers as <lb></lb>ours, to ſubſtitute in its place, in caſe we <lb></lb>ſhould break it before we learn'd the skill <lb></lb>of condencing the Air in it, we durſt not <lb></lb>put them in practice: Yet, on this occa<lb></lb>ſion, give me leave to advertiſe Your <lb></lb>Lordſhip once for all, That though for <lb></lb>the reaſons newly intimated, we have, <lb></lb>Onely in the ſeventeenth Experiment, <lb></lb>taken notice, that by the help of our En<lb></lb>gine the Air may be condenſ'd as well as <lb></lb>rarified; yet there are divers other of our <lb></lb>Experiments, whoſe <emph type="italics"></emph>Phænomena<emph.end type="italics"></emph.end> it were <pb xlink:href="013/01/244.jpg" pagenum="214"></pb>worth while to try to vary, by means of <lb></lb>the compreſſion of the Air. </s></p><p type="main"> <s>WE taught, among divers other <lb></lb><arrow.to.target n="marg35"></arrow.to.target><lb></lb>things, when we diſcourſ'd of our <lb></lb>firſt Experiment, That the Air ſhut up in <lb></lb>our Receiver, preſſeth as ſtrongly upon <lb></lb>the Bodies ſhut up with it, as if they <lb></lb>were expoſ'd to the preſſure of the whole <lb></lb>Atmoſphere. </s> <s>That this was not incon<lb></lb>ſiderately propounded, we hope Your <lb></lb>Lordſhip has gather'd from divers of the <lb></lb>things already recited: But yet perhaps it <lb></lb>will not be amiſs to ſubjoyn, by way of <lb></lb>further confirmation of the ſame truth, the <lb></lb>following Experiment, which ſhould have <lb></lb>accompanied the 20<emph type="sup"></emph>th<emph.end type="sup"></emph.end>, but the Paper where <lb></lb>in the one was written chanc'd not to beat <lb></lb>hand, when the other was ſent away. </s></p><p type="margin"> <s><margin.target id="marg35"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 28.</s></p><p type="main"> <s>We convey'd into the Receiver a new <lb></lb>Glaſs Viol, capable of holding about 6 or <lb></lb>7 ounces of Water, into which we had <lb></lb>before put 2 or 3 Spoon-fulls of that Li<lb></lb>quor, and ſtopt it cloſe with a fit Cork. <lb></lb></s> <s>The Pneumatical Veſſel being empty'd, <lb></lb>there appear'd not any change in the in<lb></lb>cloſ'd Water, the Air impriſon'd with it, <lb></lb>not having the force to blow out the ſtop-<pb xlink:href="013/01/245.jpg" pagenum="215"></pb>ple, which event, though it were no other <lb></lb>then we expected, was differing from what <lb></lb>we deſir'd. </s> <s>For we would gladly have ſeen <lb></lb>what change would have appear'd in the <lb></lb>Water upon the Bottles being ſuddenly <lb></lb>unſtopp'd, in a place where the ambient <lb></lb>Body was ſo differing from our common <lb></lb>Air. </s> <s>Wherefore we did again put in the <lb></lb>Viol, but leſs ſtrongly cloſ'd then for<lb></lb>merly, though as ſtrongly ſtopt as ſeem'd <lb></lb>requiſite on ordinary occaſions: But when <lb></lb>the Air was pump'd out of the Receiver, <lb></lb>that within the Viol did quickly, as we <lb></lb>expected, find or make it ſelf little paſſa<lb></lb>ges to get out at: as we argu'd, from this, <lb></lb>That whereas when the Viol was put in <lb></lb>the time before, the Water remain'd all <lb></lb>the while perfectly free from bubbles; at <lb></lb>this time the bottom of the Glaſs ap<lb></lb>pear'd all cover'd with them, and they, <lb></lb>upon the regreſs of the excluded Air into <lb></lb>the Receiver, did preſently flag and ſhrink <lb></lb>up. </s></p><p type="main"> <s>From theſe tryals it ſeem'd deducible <lb></lb>enough, that whil'ſt the Viol continu'd <lb></lb>to be well ſtopt, the included Water <lb></lb>did, from the Air, ſhut up with it, <lb></lb>ſuſtain a preſſure equal to that of the <lb></lb>Atmoſphere; ſince till the Air could get <pb xlink:href="013/01/246.jpg" pagenum="216"></pb>out of the Glaſs, there appear'd no bub<lb></lb>bles in the Water, notwithſtanding the <lb></lb>want of preſſure in the ambient Body. </s></p><p type="main"> <s>But to be ſure to reach the chief end of <lb></lb>our Experiment, we made uſe of this o<lb></lb>ther expedient: We cauſ'd a convenient <lb></lb>quantity of Water to be put, and Her<lb></lb>metically ſhut up into a Glaſs Egge, to <lb></lb>whoſe long Neck (which was purpoſely <lb></lb>made of an unequal thickneſs) was fa<lb></lb>ſten'd to one end of a ſtring, whoſe o<lb></lb>ther end was ty'd to the Cover of our <lb></lb>Receiver, after the manner elſewhere men<lb></lb>tion'd already: Then the Egge being <lb></lb>convey'd into the Pneumatical Veſſel, <lb></lb>and that being evacuated, we did, by <lb></lb>turning the braſs Stopple formerly de<lb></lb>ſcrib'd amongſt the parts of our En<lb></lb>gine, ſo ſhorten the ſtring as to break the <lb></lb>Glaſs; whereby liberty being given to <lb></lb>the Air impriſon'd in the Egge, to paſs <lb></lb>into the capacity of the Receiver, the ſud<lb></lb>den receſs of the Air made the bubbles in <lb></lb>a trice appear ſo numerous, and aſcend <lb></lb>ſo ſwiftly in the Water, that their motion <lb></lb>look'd like that of a violent ſhower of <lb></lb>Rain; ſave that the bubbles did not, like <lb></lb>the drops of Rain, tend downwards, but <lb></lb>upwards, which made me reſemble this <pb xlink:href="013/01/247.jpg" pagenum="217"></pb><emph type="italics"></emph>Phænomenon<emph.end type="italics"></emph.end> to what I have ſeen happen <lb></lb>in the diſſolution of Seed-Pearl in ſome <lb></lb>acid <emph type="italics"></emph>Menſtruum,<emph.end type="italics"></emph.end> in which, if a good quan<lb></lb>tity of the little Pearls be caſt whole, they <lb></lb>will at firſt, if the <emph type="italics"></emph>Menſtruum<emph.end type="italics"></emph.end> be ſharp e<lb></lb>nough, be carryed in ſwarms from the <lb></lb>bottom to the top of the Liquor. </s> <s>We <lb></lb>will adde, that without ſealing up the <lb></lb>Glaſs, this Experiment may be try'd in <lb></lb>one of our ſmalleſt Receivers, for there <lb></lb>the exſuction of the ambient Air may be <lb></lb>perform'd ſo nimbly, that immediately <lb></lb>the bubbles lurking in the Water are al<lb></lb>low'd to diſplay themſelves, and aſcend <lb></lb>in throngs; inſomuch, as having in ſuch <lb></lb>a Receiver try'd the Experiment with <lb></lb>Wine (as a more ſpirituous Liquor) in<lb></lb>ſtead of Water, the Red-Wine appear'd <lb></lb>all cover'd, with a copious, but vaniſhing <lb></lb>white Froth, almoſt as if a Veſſel full of <lb></lb>bottl'd drink had been unwarily open'd. </s></p><p type="main"> <s>IT may not a little conduce to the clear<lb></lb><arrow.to.target n="marg36"></arrow.to.target><lb></lb>er explication of divers Points in the <lb></lb>Doctrine of Meteors, and perhaps of <lb></lb>ſome other Phyſiological difficulties, to <lb></lb>diſcover what the Air does to the motion <lb></lb>of thoſe Steams or Exhalations that aſ-<pb xlink:href="013/01/248.jpg" pagenum="218"></pb>cend into it, namely, Whether they mount <lb></lb>upwards by vertue of any ſuch <emph type="italics"></emph>poſitive le<lb></lb>vity<emph.end type="italics"></emph.end> (as ſome Peripateticks ſpeak) ac<lb></lb>quir'd together with their Aërial nature, <lb></lb>as inables them to pierce through part of <lb></lb>the Atmoſphere, and over-come its re<lb></lb>ſiſtance. </s> <s>Or elſe, whether theſe ſteams <lb></lb>being once raiſ'd above the Earth by their <lb></lb>agitation, have their aſcent and ſuſtenta<lb></lb>tion aloft, rather promoted then hindred <lb></lb>by the Air: as the inferior parts of that, <lb></lb>being thicker and heavier then the ſupe<lb></lb>rior, the ſteams can more eaſily continue <lb></lb>for a while their agitation upwards then <lb></lb>downwards; And afterwards are by the <lb></lb>ſame fluidity and thickneſs of the Air, <lb></lb>carried to and fro in it, and kept from re<lb></lb>lapſing to the Earth, as in the Sea water <lb></lb>the ſaline parts are kept from ſubſiding by <lb></lb>thoſe aqueous ones wherewith they are <lb></lb>aſſociated. </s></p><p type="margin"> <s><margin.target id="marg36"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 29</s></p><p type="main"> <s>We hop'd to illuſtrate this matter, by <lb></lb>obſerving the motion of the ſmoke, pro<lb></lb>ceeding from kindled or flaming Bodies in <lb></lb>our exhauſted Receiver. </s> <s>But as we for<lb></lb>merly noted, upon the exſuction of the <lb></lb>Air, the ſmoking of thoſe Bodies pre<lb></lb>ſently ceaſ'd. </s> <s>We had thoughts alſo of <lb></lb>conveying into our Pneumatical Glaſs a <pb xlink:href="013/01/249.jpg" pagenum="219"></pb>hot Iron, with ſome Body eaſie to be <lb></lb>diſſipated into ſmoke ſet upon it, but con<lb></lb>ſider'd, that neither was that way free <lb></lb>from inconveniencies; eſpecially this, that <lb></lb>the hot Body would make the Impriſon'd <lb></lb>Air circulate within the Receiver, and <lb></lb>conſequently make it queſtionable whe<lb></lb>ther the aſcent of the ſteams would not <lb></lb>be due to the new and acquired motion of <lb></lb>the Air. </s></p><p type="main"> <s>Wherefore I bethought my ſelf of an<lb></lb>other way to ſatisfie in ſome meaſure my <lb></lb>curioſity, to wit, by means of a certain <lb></lb>Liquor, which I call'd to minde that ſome <lb></lb>years ago I had (for a deſign that belongs <lb></lb>not to our preſent purpoſe) prepar'd; <lb></lb>which, I ſuppoſe, I ſhew'd Your Lord<lb></lb>ſhip, and which had the luck to be ta<lb></lb>ken notice of by divers very Ingenious <lb></lb>and Famous Men. </s> <s>For this Liquor, <lb></lb>though moſt of its Ingredients be Metals, <lb></lb>and all of them ponderous enough, is yet <lb></lb>of that nature, that whilſt the Viol where<lb></lb>in it is kept is ſtopt (how ſlight a Cover <lb></lb>ſoever) both the Liquor and the Glaſs <lb></lb>are tranſparent; and ſo is that upper half <lb></lb>of the Glaſs to which the Liquor reaches <lb></lb>not. </s> <s>But aſſoon as ever the ſtopple is ta<lb></lb>ken out, and full acceſs is given to the ex-<pb xlink:href="013/01/250.jpg" pagenum="220"></pb>ternal Air, both the inward part of the <lb></lb>Cork, and the Liquor it ſelf, do preſent<lb></lb>ly ſend upwards, and ſcatter abroad a <lb></lb>fume as thick and white, as if there were <lb></lb>a quantity of Alablaſter-duſt thrown up <lb></lb>into the Air: And this ſmoking of the <lb></lb>Liquor laſts till my unwillingneſs to waſte <lb></lb>it, invites me ſtop it again; and then the <lb></lb>aſcenſion of the fumes ſuddenly ceaſes, till <lb></lb>the Viol be again unſtop'd. </s></p><p type="main"> <s>This fuming Liquor then I thought <lb></lb>would much conduce to the diſcovery I <lb></lb>deſir'd to make, ſince it ſav'd me the need <lb></lb>of conveying any hot Body with it into <lb></lb>the Receiver, and would not darken it <lb></lb>with fumes before the time. </s> <s>Wherefore <lb></lb>having ty'd to the Viol a great weight of <lb></lb>Lead, to keep it from being lifted up by <lb></lb>the drawing out of the Cork; and having <lb></lb>ty'd to the ſtopple one end of a ſtring, of <lb></lb>which the other end was made faſt to the <lb></lb>Cover of the Pneumatical Glaſs, the Li<lb></lb>quor was carefully cloſ'd up after the <lb></lb>wonted manner; then the Air being dili<lb></lb>gently pump'd out, the Viol was unſtopt <lb></lb>in the empty'd Receiver: and though <lb></lb>immediately, npon the drawing out of the <lb></lb>Cork, there appear'd to be as it were <lb></lb>thrown up ſome white fumes, which <pb xlink:href="013/01/251.jpg" pagenum="221"></pb>ſeem'd to proceed from the Air before <lb></lb>impriſon'd in the Viol, and diffuſing it <lb></lb>ſelf ſuddenly into the capicity of the <lb></lb>Receiver. </s> <s>Yet we afterward obſerv'd, <lb></lb>as we expected, That the fumes did not <lb></lb>mount and diſperſe themſelves as they <lb></lb>uſe to do in the open Air, but that, when <lb></lb>by reaſon of the agitation of the Cor<lb></lb>puſcles of the Liquor, which could not <lb></lb>continue their motion in ſo narrow a <lb></lb>ſpace as the Viol afforded them, and were <lb></lb>therefore reduc'd to thruſt one another <lb></lb>out of it; when, I ſay, by theſe aſſi<lb></lb>ſtances the fumes were aſcended to the lip <lb></lb>of the Viol, they mounted no higher, <lb></lb>but ran down along the out-ſide of the <lb></lb>Viol to the bottom of it; and thence <lb></lb>along, a long and inclining piece of Lead, <lb></lb>on which the Viol reſted, like a little <lb></lb>Stream (not very much bigger then a <lb></lb>Swans Quill) whoſe nature it ſeemd to e<lb></lb>mulate ſo well, that it quitted not the Viol <lb></lb>till it was come to the bottom of it, and <lb></lb>then forſook it in ſuch a manner as a <lb></lb>ſtream of Water of the ſame bigneſs <lb></lb>would have done. </s> <s>And this ſtream laſted <lb></lb>a pretty while, and would probably have <lb></lb>laſted longer, but that being loath to waſte <lb></lb>my Liquor, I let in at the Stop-cock a <pb xlink:href="013/01/252.jpg" pagenum="222"></pb>pretty deal of the external Air; notwith<lb></lb>ſtanding which, finding after a while the <lb></lb>ſtream did run afreſh; though, as it ſeem'd, <lb></lb>not altogether ſo copious as before: I let <lb></lb>as much more Air, as would, come in, and <lb></lb>found (ſomewhat to my wonder) that <lb></lb>though the ſtream formerly mention'd <lb></lb>diſ-appear'd, yet there appear'd not any <lb></lb>white fumes to ariſe, either from the Cork, <lb></lb>or out of the Viol it ſelf, no not when <lb></lb>the Cover was remov'd from the Recei<lb></lb>ver; though not onely after a while there <lb></lb>aſcended white Fumes from the Receiver: <lb></lb>but having forthwith taken out the Viol <lb></lb>into the open Air, it emitted white ex<lb></lb>halations as before; and having preſently <lb></lb>after unſtop'd it in an open Window, we <lb></lb>found both it and the Cork immediatly <lb></lb>to ſend forth a yet much more plentiful <lb></lb>ſmoak. </s> <s>Though it be now divers years <lb></lb>ſince this Numerical Liquor was prepa<lb></lb>red, after the manner mention'd either <lb></lb>by <emph type="italics"></emph>Carneiades<emph.end type="italics"></emph.end> or <emph type="italics"></emph>Eleutherius<emph.end type="italics"></emph.end> (for I do not <lb></lb>well remember which) in thoſe Dialogues <lb></lb>concerning Heat and Flame that have a<lb></lb>bove been mention'd. </s></p><p type="main"> <s>More Circumſtances concerning theſe <lb></lb>Fumes we might have obſerv'd, had we <lb></lb>not been deterr'd by an Indiſpoſition in <pb xlink:href="013/01/253.jpg" pagenum="223"></pb>point of health, from having much to do <lb></lb>with ſteams of ſo dangerous a nature, as by <lb></lb>that of the Ingredients of this Liquor <lb></lb>theſe ſeem likely to be of. </s></p><p type="main"> <s>The Reflections that may be made up<lb></lb>on this Experiment, we have not now the <lb></lb>leaſure to proſecute, and therefore ſhall <lb></lb>content our ſelves to recommend the ſe<lb></lb>veral Circumſtances of it to Your Lord<lb></lb>ſhips ſerious conſideration; and to take <lb></lb>notice <emph type="italics"></emph>(en paſſant)<emph.end type="italics"></emph.end> that ſteams in an am<lb></lb>bient Body, or a medium thinner then <lb></lb>themſelves, may both tend downwards, <lb></lb>and otherwiſe emulate the nature of a <lb></lb>Liquor; which I therefore point at, that <lb></lb>it may appear the leſs ſtrange, if we ſome<lb></lb>times ſpeak of the Atmoſphere as of a <lb></lb>kinde of Liquor, in compariſon of that <lb></lb>more thin and ſubtle Celeſtial Matter that <lb></lb>ſurrounds it. </s></p><p type="main"> <s>And though it might perchance ſuf<lb></lb>fice to have on this occaſion intima<lb></lb>ted thus much; yet, leſt this way <lb></lb>of ſpeaking of the Atmoſphere ſhould <lb></lb>be thought too bold and extra<lb></lb>vagant, I am content to borrow an <lb></lb>Experiment of the Diſcourſe former-<pb xlink:href="013/01/254.jpg" pagenum="224"></pb>ly mention'd (touching fluidity and firm<lb></lb>neſs) and ſubjoyn it here with alterations <lb></lb>ſuitable to the contrivance of our Engine; <lb></lb>and this the rather, becauſe I hope it may <lb></lb>conduce to the diſcovery of the nature of <lb></lb>the Atmoſphere: for which reaſon it <lb></lb>might have been annext to what has been <lb></lb>noted either upon the firſt, or eighteenth <lb></lb>Experiment, but that when they were <lb></lb>written and ſent away, it came not into <lb></lb>my minde. </s> <s>The Experiment then as we <lb></lb>try'd in our Engine, was as follows. </s></p><p type="main"> <s>WE took one of the ſmall Receivers, <lb></lb><arrow.to.target n="marg37"></arrow.to.target><lb></lb>often mention'd already, and into it <lb></lb>we convey'd a piece of well lighted Match; <lb></lb>and letting it remain there till it had fill'd <lb></lb>the Receiver with ſmoak, we took it out <lb></lb>and haſtily cloſ'd again the Receiver, that <lb></lb>the ſmoak might not get away. </s> <s>Then <lb></lb>ſtaying awhile to let theſe fumes leiſurely <lb></lb>ſubſide, we found, as we expected, that <lb></lb>after ſome time they ſetled themſelves in <lb></lb>the lower half of the Receiver, in a dark<lb></lb>iſh Body, leaving the upper half of the <lb></lb>Receiver tranſparent, and as to ſight, full <lb></lb>of nought but clear Air. </s> <s>Now to mani<lb></lb>feſt that this ſmoak thus ſetled emulated <pb xlink:href="013/01/255.jpg" pagenum="225"></pb>a Liquor, we inclin'd the Engine that con<lb></lb>tain'd it, ſometimes to one ſide, and ſome<lb></lb>times to the other; and obſerv'd the <lb></lb>ſmoak to keep its ſurface almoſt Hori<lb></lb>zontal, notwithſtanding the ſtooping of <lb></lb>the Veſſel that held it, as Water or an<lb></lb>other Liquor would in the like caſe have <lb></lb>done. </s> <s>And if by a quicker rocking of the <lb></lb>Engine the ſmoke were more ſwiftly ſha<lb></lb>ken, it would, like Water, either Vibrate <lb></lb>to and fro from one ſide to the other of <lb></lb>the Glaſs, or elſe have its ſurface manifeſt<lb></lb>ly curll'd with Waves, but preſerve its <lb></lb>ſelf in an intire and diſtinct Body from the <lb></lb>incumbent Air; and being permitted to <lb></lb>reſt awhile, would ſoon recover its for<lb></lb>mer ſmooth and level <emph type="italics"></emph>ſuperficies:<emph.end type="italics"></emph.end> If alſo <lb></lb>the Key were turn'd and the Valve un<lb></lb>ſtopp'd, ſo that there was a free, though <lb></lb>but a narrow paſſage open'd betwixt the <lb></lb>external Air and the cavity of the Recei<lb></lb>ver, then would ſome of this ſmoak fall <lb></lb>down, as it were, in a ſtream into the ſub<lb></lb>jacent Cylinder, and a proportionate <lb></lb>quantity of the outward Air, would ma<lb></lb>nifeſtly aſcend through it into the incum<lb></lb>bent Air, much after the ſame manner as <lb></lb>if you invert a Viol with a long Neck, and <lb></lb>well fill'd with Red-Wine, into a Glaſs <pb xlink:href="013/01/256.jpg" pagenum="226"></pb>full of fair water, you ſhall ſee the Water <lb></lb>and Wine by degrees mingle with one an<lb></lb>other; the one falling downe as it were in <lb></lb>little colour'd ſtreames, and the other aſ<lb></lb>cending into its room in the like curled <lb></lb>ſtreames, ſometimes preceded by round <lb></lb>parcels of water, which, by reaſon of their <lb></lb>tranſparency, looke almoſt like bubbles. <lb></lb></s> <s>The other circumſtances of this Experi<lb></lb>ment, belonging not all of them to our <lb></lb>preſent purpoſe, we ſhall content our <lb></lb>ſelves with taking notice of one which <lb></lb>ſeemes the moſt important, and may illu<lb></lb>ſtrate and confirme ſome things former<lb></lb>ly delivered. </s> <s>And it was, That if, when <lb></lb>the <emph type="italics"></emph>ſuperficies<emph.end type="italics"></emph.end> of our Smoke lay ſmooth <lb></lb>and horizontal, a hot iron were held near <lb></lb>the our ſide of the Receiver, the Neigh<lb></lb>bouring part of the included fumes (for <lb></lb>the reſt did not very much alter their for<lb></lb>mer <emph type="italics"></emph>ſuperficies<emph.end type="italics"></emph.end>) being rarified by the heat, <lb></lb>would readily aſcend in a large Pillar of <lb></lb>ſmoke to the very top of the Receiver, <lb></lb>yet without ſeeming to looſe a diſtinct <lb></lb><emph type="italics"></emph>ſuperficies,<emph.end type="italics"></emph.end> or to be confounded with Air; <lb></lb>below which, upon the receſs of the ad<lb></lb>ventitious heat that by agitating it im<lb></lb>pell'd it upward, it would againe ſub<lb></lb>ſide. </s></p><pb xlink:href="013/01/257.jpg" pagenum="227"></pb><p type="margin"> <s><margin.target id="marg37"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 30.</s></p><p type="main"> <s>All which being added to the late Ex<lb></lb>periment of the ſmoking Liquor, and <lb></lb>to what may be from that which has been <lb></lb>elſewhere ſayd, gather'd to the ſame pur<lb></lb>poſe, will, I hope, keep it at leaſt from ap<lb></lb>pearing abſur'd: If ſince we ſee that there <lb></lb>is ſo great an inequality in the denſity and <lb></lb>weight of Liquors, that water is neere 14 <lb></lb>times thinner or lighter than Quick-ſilver <lb></lb>of the ſame bulk, and well dephlegm'd; <lb></lb>Spirit of Wine yet much lighter than wa<lb></lb>ter; we venter to ſpeak ſometimes of the <lb></lb>Atmoſphere, as if it were a peculiar kind <lb></lb>of thin and halituous Liquor (if I may ſo <lb></lb>call it) much lighter than Spirit of Wine. </s></p><p type="main"> <s>To theſe things I know not whether it <lb></lb>will be requiſite to add, that as we late<lb></lb>ly took notice of conſpicuous waves that <lb></lb>appear'd upon the <emph type="italics"></emph>ſuperficies<emph.end type="italics"></emph.end> of our agi<lb></lb>tated ſmoke. </s> <s>So ſome ſuch thing may <lb></lb>not abſurdly be conjectur'd to happen <lb></lb>on the <emph type="italics"></emph>ſuperficies<emph.end type="italics"></emph.end> of the Atmoſphere, <lb></lb>by thoſe ſtrange ruggedneſſes that ap<lb></lb>peare (eſpecially in the Spring and Fall, <lb></lb>when exhalations and vapours are wont to <lb></lb>aſcend moſt plentifully) upon the Limb <lb></lb>or Edge of the Riſing and Setting Sun. </s> <s>I <lb></lb>ſpeake thus diffidently upon this occaſion <lb></lb>becauſe I know that by the Fluctuation or <pb xlink:href="013/01/258.jpg" pagenum="228"></pb>Boyling of the Sun's own <emph type="italics"></emph>ſuperficies<emph.end type="italics"></emph.end> di<lb></lb>verſe eminent Mathematicians have plau<lb></lb>ſibly enough (but how truly I leave <lb></lb>your Lordſhip to Judge) endeavour'd to <lb></lb>give an Account of it. </s> <s>But if we will joine <lb></lb>with thoſe that have aſcrib'd of late this <lb></lb><emph type="italics"></emph>Phænomenon<emph.end type="italics"></emph.end> to the Refraction the Sun<lb></lb>Beames fuffer in our vapid Air; we may, <lb></lb>as hath been intimated, promote their Do<lb></lb>ctrin by deducing from it, that probably <lb></lb>the ſurface Atmoſphere is oftentimes (if <lb></lb>not alwayes) exceedingly curl'd or wav'd. <lb></lb></s> <s>And certainly it is ſomewhat wonderfull <lb></lb>as well as very pleaſant to behold, how, <lb></lb>to him that looks upon the ſetting Sun <lb></lb>through a long & excellent Teleſcope, <lb></lb>there will not only appeare ſtrange ine<lb></lb>qualities in the edge of it (inſomuch that <lb></lb>I have often ſeen it more indented than a <lb></lb>Saw) but thoſe inequalities will vaniſh in <lb></lb>one place and preſently appeare in ano<lb></lb>ther, and ſeem perfectly to move like <lb></lb>waves ſucceeding and deſtroying one an<lb></lb>other; ſave that their Motion oftentimes <lb></lb>ſeemes to be quickeſt as if in that vaſt ſea <lb></lb>they were carried on by a current, or at <lb></lb>leaſt by a tide. </s> <s>And this (as we elſe <lb></lb>where note) appear's to the eye not on<lb></lb>ly when it looks directly through the te-<pb xlink:href="013/01/259.jpg" pagenum="229"></pb>leſcope upon the ſunne; but alſo when a <lb></lb>large and well defin'd image of the ſunne <lb></lb>is by the ſame teleſcope brought into a <lb></lb>roome and caſt upon a ſheet of white pa<lb></lb>per. </s> <s>But to inſiſt on this were to digreſs: <lb></lb>and therefore I will proceed to experi<lb></lb>ments of another kind. </s></p><p type="main"> <s>IT has been admir'd by very ingenious <lb></lb><arrow.to.target n="marg38"></arrow.to.target><lb></lb>Men, that if the exquiſitly poliſh'd <lb></lb>ſurfaces of two flat peeces of marble be ſo <lb></lb>congruous to each other that from their <lb></lb>mutuall application there will reſult an <lb></lb>immediate contact, they will ſtick ſo faſt <lb></lb>together, that he that lifts up the upper<lb></lb>moſt, ſhall, if the undermoſt be not ex<lb></lb>ceeding heavy, lift up that too, and ſuſ<lb></lb>taine it aloft in the free aire. </s> <s>A proba<lb></lb>ble cauſe of this ſo cloſe adheſion we have <lb></lb>elſewhere endeavour'd to deduce from the <lb></lb>unequall preſſure of the Air upon the un<lb></lb>dermoſt ſtone; For the lower <emph type="italics"></emph>ſuperficies<emph.end type="italics"></emph.end><lb></lb>of that ſtone being freely expos'd to the <lb></lb>Air is preſſ'd upon by it, whereas the up<lb></lb>permoſt ſurface, being contiguous to the <lb></lb>ſuperiour ſtone, is thereby defended from <lb></lb>the preſſure of the Air which conſequent<lb></lb>ly preſſing the lower ſtone againſt the up-<pb xlink:href="013/01/260.jpg" pagenum="230"></pb>per, hinders it from falling, as we have <lb></lb>elſewhere more fully declar'd. </s> <s>Upon <lb></lb>theſe grounds we conjectur'd that in caſe <lb></lb>we could procure two marbles exactly <lb></lb>ground to one another; and in caſe we <lb></lb>could alſo ſufficiently evacuate our Re<lb></lb>ceiver, the lower ſtone would, for want <lb></lb>of the wonted and ſuſtaining preſſure of <lb></lb>the Air, fall from the upper. </s> <s>But the <lb></lb>further tryal of this Experiment we muſt, <lb></lb>unleſs your Lordſhip think it worth Your <lb></lb>making at <emph type="italics"></emph>Paris,<emph.end type="italics"></emph.end> put off till a fitter <lb></lb>opportunity. </s> <s>For where we now are, we <lb></lb>cannot procure marbles ſo exactly ground, <lb></lb>that they will ſuſtaine one another in the <lb></lb>Air, above a minute or two, which is a <lb></lb>much ſhorter time than the emptying of <lb></lb>our Receiver requires. </s> <s>We did indeed <lb></lb>try to make our marbles ſtick cloſe to<lb></lb>gether by moiſtening their polliſhed ſur<lb></lb>faces with rectifi'd ſpirit of Wine, in re<lb></lb>gard that Liquor by its ſudden avolation <lb></lb>from marble, if powr'd thereon, without <lb></lb>leaving it moiſt or leſs ſmooth, ſeem'd <lb></lb>unable to ſuſtaine them together after the <lb></lb>manner of a glutinous body, and yet <lb></lb>ſeem'd ſufficient to exclude and keep out <lb></lb>the Air. </s> <s>But this we try'd to little pur<lb></lb>poſe, for having convey'd into the Recei-<pb xlink:href="013/01/261.jpg" pagenum="231"></pb>ver two black ſquare marbles (the one of <lb></lb>two inches and a third in length or <lb></lb>breadth, and ſomewhat more than halfe <lb></lb>an inch in thickneſs: The other of the ſame <lb></lb>extent, but not much above halfe ſo <lb></lb>thick) faſten'd together by the interven<lb></lb>tion of pure Spirit of Wine; and having <lb></lb>ſuſpended the thicker by a ſtring from the <lb></lb>cover, we found not that the exſuction of <lb></lb>the ambient Air would ſeparate them, <lb></lb>though a weight amounting to four oun<lb></lb>ces were faſten'd to the lowermoſt mar<lb></lb>ble to facilitate it's falling off. </s></p><p type="margin"> <s><margin.target id="marg38"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 31,</s></p><p type="main"> <s>I would gladly have the Experiment <lb></lb>try'd with marble ſo well polliſh't as to <lb></lb>need no Liquor whatſoever to make them <lb></lb>cohere, and in a Veſſel out of which the <lb></lb>Air may be more perfectly drawn than it <lb></lb>was out of ours. </s> <s>But in the mean time <lb></lb>though we will not determin whether the <lb></lb>Spirit of wine did contribute to the ſtrong <lb></lb>coheſion of theſe ſtones, otherwiſe than <lb></lb>by keeping ev'n the ſubtl'ſt parts of the <lb></lb>Air from getting in between them, yet it <lb></lb>ſeemed that the not falling downe of the <lb></lb>lowermoſt marble might without impro<lb></lb>bability be aſcrib'd to the preſſure of the <lb></lb>Air remaining in the Receiver; which as <lb></lb>we formerly noted having been able <pb xlink:href="013/01/262.jpg" pagenum="232"></pb>to keep a Cylinder of water of above <lb></lb>a Foot in height from falling to the bot<lb></lb>tom of the Tube, may well enough be <lb></lb>ſuppoſ'd capable of keeping ſo broad a flat <lb></lb>Marble from deſcending. </s> <s>And though this <lb></lb>may ſeem a ſtrange proof of the ſtrength of <lb></lb>the ſpring of Air, ev'n when rarified, yet it <lb></lb>will ſcarce ſeem incredible to him that has <lb></lb>obſerv'd how exceeding ſtrong a coheſion <lb></lb>may be made betwixt broad Bodies, one<lb></lb>ly by their immediate touching one ano<lb></lb>ther. </s> <s>A notable inſtance of which, I <lb></lb>have met with in this ſhort Narrative of <lb></lb><arrow.to.target n="marg39"></arrow.to.target><lb></lb>the Learned <emph type="italics"></emph>Zucchius. </s> <s>Fuveni<emph.end type="italics"></emph.end> (ſays he) <lb></lb><emph type="italics"></emph>lacertorum ſuorum robur: jactanti propo<lb></lb>ſita ſemel eſt lamina ærea, per anſam in <lb></lb>medio extantem apprehenſam elevanda è <lb></lb>tabula marmorea, cui optime congruebat: <lb></lb>qui primo tanquam rem ludicr am puero <lb></lb>committendam contempſit: tum inſtanti<lb></lb>bus amicis manum utrámque admovens, <lb></lb>cum luctatus diu hærentem non removiſſet, <lb></lb>excuſavit impotentiam, objecta perigrini <lb></lb>& potentiſsimi glutinis interpoſitione, quo <lb></lb>fortiſsime copulante nequiret divelli; do<lb></lb>nec vidit ab alio per tabulam facilimè lami<lb></lb>nam deduci, & ad extrema product am, & <lb></lb>actam in tranſverſum inàe deportari.<emph.end type="italics"></emph.end></s><s> But <lb></lb>that we may learn from our own Engine, <pb xlink:href="013/01/263.jpg" pagenum="233"></pb>that two Bodies, though they touch each <lb></lb>other but in a ſmall part of their ſurfaces, <lb></lb>may be made to cohere very ſtrongly, <lb></lb>onely by this, That the Air preſſes much <lb></lb>more forcibly upon the inferior ſuperfi<lb></lb>cies of the lowermoſt Body, then upon <lb></lb>the upper ſurface of the ſame: We will <lb></lb>hereunto annex the following Experi<lb></lb>ment, though out of the order wherein <lb></lb>they were made. <lb></lb><arrow.to.target n="marg40"></arrow.to.target></s></p><p type="margin"> <s><margin.target id="marg39"></margin.target><emph type="italics"></emph>P. Nic. <lb></lb></s> <s>Zucchius <lb></lb>opal Schot: <lb></lb>part<emph.end type="italics"></emph.end> 1. <lb></lb><gap></gap></s></p><p type="margin"> <s><margin.target id="marg40"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 32.</s></p><p type="main"> <s>I remember I have, in a Diſcourſe con<lb></lb>cerning Fluidity and Firmneſs, made <lb></lb>mention of my having, by the exſuction <lb></lb>of the Air out of a Glaſs Veſſel, made <lb></lb>that Veſſel take up, or ſuck up (to ſpeak in <lb></lb>the common Language) a Body weighing <lb></lb>divers Ounces; but our Engine affording <lb></lb>us the opportunity of making conſider<lb></lb>abler Experiments of that kinde, We <lb></lb>thought fit to make a further tryal of the <lb></lb>force of the Atmoſphere's preſſure up<lb></lb>wards, after the following manner. </s></p><p type="main"> <s>The Receiver having been exquiſitely <lb></lb>cloſ'd, as we have often taught already, <lb></lb>and the Air being in a good meaſure drawn <lb></lb>out of it, it was remov'd from off the <lb></lb>Pump: and to the lower Branch of the <pb xlink:href="013/01/264.jpg" pagenum="234"></pb>Stop-cock, there was ſpeedily apply'd a <lb></lb>tapering Valve of braſs, ſuch as is deſcrib'd <lb></lb>in the 9<emph type="sup"></emph>th<emph.end type="sup"></emph.end> fig: made fit to go with its nar<lb></lb>rower end into the cavity of the branch, <lb></lb>and to fill the orifice of that cavity with <lb></lb>its broader part. </s> <s>And that the Air might <lb></lb>not get in at the litle intervals, left here <lb></lb>and there between the convex ſurface of <lb></lb>the ſtopple and the internall edge of the <lb></lb>branch, thoſe intervals were ſtop't with <lb></lb>a little Diachylon. </s> <s>And to the doore, <lb></lb>or, (if you pleaſe) that part of the Valve <lb></lb>which was to move to and fro, and in <lb></lb>this Experiment hung perpendicular to <lb></lb>the Horizon, there was, at a button of <lb></lb>braſs belonging to the Valve faſten'd a <lb></lb>broad ſcale wherein weights were to be <lb></lb>put. </s> <s>This done the key of the Stop-cock <lb></lb>was turn'd, and the externall Air beating <lb></lb>like a forcible ſtreame upon the Valve <lb></lb>to get in there, it did ſuddenly both ſhut <lb></lb>the Valve and keep it ſhut ſo ſtrongly, <lb></lb>that we had time to caſt in diverſe weights <lb></lb>one after another into the Scale; till at <lb></lb>length the weight overpowering the preſ<lb></lb>ſure of the Atmoſphere, drew downe the <lb></lb>Valve by the ſtringes that ty'd the Scale <lb></lb>to it, and gave liberty to the outward Air <lb></lb>to ruſh into the Receiver. </s> <s>Though a-<pb xlink:href="013/01/265.jpg" pagenum="235"></pb>nother time, when the Valve had but lit<lb></lb>tle weight hanging at it, being, by I know <lb></lb>not what accident, drawn down beneath its <lb></lb>former place, it was by the impetuous <lb></lb>current of the outward Air ſuddenly im<lb></lb>pell'd up into it again, and kept there. <lb></lb></s> <s>But in the former Experiment it is re<lb></lb>markable, That though the Receiver were <lb></lb>not well exhauſted, and though it leak'd <lb></lb>whil'ſt the reſt of the Experiment was in <lb></lb>proſecution, and though the Valve <lb></lb>whereon the Cylinder of the Atmoſphere <lb></lb>could preſs, were not above an Inch and <lb></lb>a half in Diameter, yet the weight kept <lb></lb>up by ſuction, or rather ſupported by the <lb></lb>Air, namely the Valve, the Seal and <lb></lb>what was caſt into it, being ſent to be <lb></lb>weigh'd, amounted to about ten of our <lb></lb>common Pounds, conſiſting of ſixteen <lb></lb>Ounces apiece: So that we doubted not <lb></lb>but that, had the Experiment been made <lb></lb>with favorable Circumſtances, the Air <lb></lb>endeavoring to preſs in at the Orifice of <lb></lb>the Stop-cock, would have kept a very <lb></lb>much greater weight from falling out of <lb></lb>it; I ſay the Air, becauſe we found, by <lb></lb>tryal purpoſely made, that neither the <lb></lb>imperfect contact of the Valve and the <lb></lb>Stop-cock, nor the Diachylon that was <pb xlink:href="013/01/266.jpg" pagenum="236"></pb>employ'd to fill up the little Crannies left <lb></lb>betwixt them, were conſiderable in this <lb></lb>Experiment; by which may among other <lb></lb>things appear, that I did not without <lb></lb>cauſe in the above-nam'd Diſcourſe touch<lb></lb>ing Fluidity and Firmneſs, aſcribe a great <lb></lb>force, ev'n to ſuch Pillars of Air as may <lb></lb>be ſuppoſ'd to begin at the top of the <lb></lb>Atmoſphere, and recoyling from the <lb></lb>ground to terminate on the Bodies on <lb></lb>which they preſs: ſince in the preſent Ex<lb></lb>periment ſuch a weight was ſupported by <lb></lb>ſo ſlender a Cylinder of Air, rebounding <lb></lb>from the Earth to the Valve whereon it <lb></lb>did bear. </s></p><p type="main"> <s>BUt in regard we have not yet been <lb></lb><arrow.to.target n="marg41"></arrow.to.target><lb></lb>able to empty ſo great a Veſſel as our <lb></lb>Receiver, ſo well as we can the Cylinder <lb></lb>it ſelf; our Pump alone may afford us a <lb></lb>nobler inſtance of the fotce of the Air we <lb></lb>live in, inſomuch, that by help of this <lb></lb>part of our Engine, we may give a pretty <lb></lb>near gheſs at the ſtrength of the Atmo<lb></lb>ſphere, computed as a weight. </s> <s>And the <lb></lb>way may be this; Firſt, the Sucker be<lb></lb>ing brought to move eaſily up and down <lb></lb>the Cylinder, is to be impell'd to the top <pb xlink:href="013/01/267.jpg" pagenum="237"></pb>of it: Then the Receiver muſt be taken <lb></lb>off from the Pump, that the upper Ori<lb></lb>fice of the Cylinder remaining open, the <lb></lb>Air may freely ſucceed the Sucker, and <lb></lb>therefore readily yield to its motion <lb></lb>downward. </s> <s>This done, there muſt be <lb></lb>faſten'd to one of the Iron Teeth of the <lb></lb>Sucker, ſuch a weight as may juſt ſuffice <lb></lb>to draw it to the bottom of the Cylinder. <lb></lb></s> <s>And having thus examin'd what weight is <lb></lb>neceſſary to draw down the Sucker, when <lb></lb>the Atmoſphere makes no other then the <lb></lb>ordinary reſiſtance of the Air againſt its <lb></lb>deſcent; the Sucker muſt be again forc'd <lb></lb>to the top of the Cylinder, whoſe upper <lb></lb>Orifice muſt now be exactly cloſed; and <lb></lb>then (the firſt weight remaining) we eaſi<lb></lb>ly may, by hanging a Scale to the above<lb></lb>mention'd Iron (that makes part of the <lb></lb>Sucker) caſt in known weights ſo long, <lb></lb>till in ſpight of the reluctancy of the At<lb></lb>moſphere the Sucker be drawn down. </s> <s>For <lb></lb>to theſe weights in the Scale, that of the <lb></lb>Scale it ſelf being added, the ſum will give <lb></lb>us the weight of a Column of Air, equal <lb></lb>in Diameter to the Sucker, or to the ca<lb></lb>vity of the Cylinder; and in length to <lb></lb>the heighth of the Atmoſphere. </s></p><p type="margin"> <s><margin.target id="marg41"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 33.</s></p><p type="main"> <s>According to this method we did, ſince <pb xlink:href="013/01/268.jpg" pagenum="238"></pb>the writing of the laſt Experiment, at<lb></lb>tempt to meaſure the preſſure of the At<lb></lb>moſphere, but found it more difficult then <lb></lb>we expected, to perform it with any ac<lb></lb>curateneſs; for though by the help of the <lb></lb><emph type="italics"></emph>Manubrium<emph.end type="italics"></emph.end> the Sucker moved up and <lb></lb>down with ſo much eaſe, that one would <lb></lb>have thought that both its convex ſurface, <lb></lb>and the concave one of the Cylinder were <lb></lb>exquiſitely ſmooth, & as it were ſlippery; <lb></lb>yet when the Sucker came to be moved <lb></lb>onely with a dead weight or preſſure (that <lb></lb>was not (like the force of him that <lb></lb>pump'd) intended as occaſion required) <lb></lb>we found that the little rufneſſes, or other <lb></lb>inequalities, and perhaps too, the unequal <lb></lb>preſſure of the Leather againſt the cavity <lb></lb>of the Cylinder, were able now and then <lb></lb>to put a ſtop to the deſcent or aſcent of <lb></lb>the Sucker, though a very little external <lb></lb>help would eaſily ſurmount that impedi<lb></lb>ment; and then the Sucker would, for a <lb></lb>while, continue its formerly interrupted <lb></lb>motion, though that aſſiſtance were with<lb></lb>drawn. </s> <s>But this diſcouragement did not <lb></lb>deterre us from proſecuting our Experi<lb></lb>ment, and endeavoring, by a careful trial, <lb></lb>to make it as inſtructive as we could. <lb></lb></s> <s>We found then that a Leaden Weight, <pb xlink:href="013/01/269.jpg" pagenum="239"></pb>of 28 pounds (each conſiſting of ſixteen <lb></lb>Ounces) being faſtned to one of the teeth <lb></lb>of the Sucker, drew it down ſlowly e<lb></lb>nough; when the upper Orifice of the <lb></lb>Cylinder was left open, though by the <lb></lb>help of Oyl and Water, and by the fre<lb></lb>quent moving the Sucker up and down <lb></lb>with the <emph type="italics"></emph>Manubrium,<emph.end type="italics"></emph.end> its motion in the <lb></lb>Cylinder had been before purpoſely faci<lb></lb>litated. </s> <s>This done, the upper Orifice of <lb></lb>the Cylinder was very carefully and cloſe<lb></lb>ly ſtopp'd, the Valve being likewiſe ſhut <lb></lb>with its wonted Stopple well oyl'd, af<lb></lb>ter the Sucker had been again impell'd <lb></lb>up to the top of the Cylinder. </s> <s>Then to <lb></lb>the precedent twenty eight pound, we <lb></lb>added a hundred and twelve pounds more, <lb></lb>which forcing down the Sucker, though <lb></lb>but leiſurely, we took off the twenty <lb></lb>eight pound weight; and being unable to <lb></lb>procure juſt ſuch weights as we would <lb></lb>have had, we hung on, inſtead of it, one <lb></lb>of fourteen pound, but found that, with <lb></lb>the reſt, unable to carry down the Sucker. <lb></lb></s> <s>And to ſatisfie our ſelves, and the Spe<lb></lb>ctators, that it was the reſiſtance of the <lb></lb>ambient Air that hinder'd the deſcent of <lb></lb>ſo great a weight, after that we had try'd <lb></lb>that upon unſtopping the Valve, and <pb xlink:href="013/01/270.jpg" pagenum="240"></pb>thereby opening an acceſs to the external <lb></lb>Air, the Sucker would be immediately <lb></lb>drawn down: After this, I ſay, we made <lb></lb>this further Experiment, That having by <lb></lb>a Man's ſtrength forcibly depreſſ'd the <lb></lb>Sucker to the bottom of the Cylinder, <lb></lb>and then faſtned weights to the above<lb></lb>named Iron that makes part of that Suc<lb></lb>ker, the preſſure of the external Air find<lb></lb>ing little or nothing in the cavity of the <lb></lb>evacuated Cylinder to reſiſt it, did pre<lb></lb>ſently begin to impell the Sucker, with <lb></lb>the weights that clogg'd it, towards the <lb></lb>upper part of the Cylinder, till ſome <lb></lb>ſuch accidental Impediment as we former<lb></lb>ly mention'd, check'd its courſe; and <lb></lb>when that rub, which eaſily might be, was <lb></lb>taken out of the way, it would continue <lb></lb>its aſcent to the top, to the no ſmall won<lb></lb>der of thoſe By ſtanders, that could not <lb></lb>comprehend how ſuch a weight could aſ<lb></lb>cend, as it were, of it ſelf; that is, with<lb></lb>out any viſible force, or ſo much as Su<lb></lb>ction to lift it up. </s> <s>And indeed it is very <lb></lb>conſiderable, that though poſſibly there <lb></lb>might remain ſome particles of Air in the <lb></lb>Cylinder, after the drawing down of the <lb></lb>Sucker; yet the preſſure of a Cylinder of <lb></lb>the Atmoſphere, ſomewhat leſs then <pb xlink:href="013/01/271.jpg" pagenum="241"></pb>three Inches in Diameter (for, as it was <lb></lb>ſaid in the deſcription of our Engine, the <lb></lb>cavity of the Cylinder was no broader) <lb></lb>was able, uncompreſſ'd, not only to ſuſtain, <lb></lb>but even to drive up a weight of an hun<lb></lb>dred and odde pounds: for beſides the <lb></lb>weight of the whole Sucker it ſelf, which <lb></lb>amounts to ſome pounds, the weights an<lb></lb>nexed to it made up a hundred and three <lb></lb>pounds, beſides an Iron Bar, that by con<lb></lb>jecture weighed two pounds more; and <lb></lb>yet all theſe together fall ſomewhat ſhort <lb></lb>of the weight which we lately mention'd, <lb></lb>the reſiſtance of the Air to have held ſu<lb></lb>ſpended in the cavity of the Cylinder. </s></p><p type="main"> <s>And though (as hath been already ac<lb></lb>knowledg'd) we cannot, peradventure, <lb></lb>obtain by the recited means ſo exact an <lb></lb>account as were to be wiſh'd, of what we <lb></lb>would diſcover: Yet, if it ſerve us to <lb></lb>ground Conjectures more approaching to <lb></lb>the Truth, then we have hitherto met <lb></lb>with, I hope it will be conſider'd (which <lb></lb>a famous Poet judiciouſly ſays) </s></p><p type="main"> <s><emph type="center"></emph><emph type="italics"></emph>Eſt quoddam prodire tenus, ſi non da<lb></lb>tur ultra.<emph.end type="italics"></emph.end><emph.end type="center"></emph.end></s></p><p type="main"> <s>Peradventure it will not be imperti-<pb xlink:href="013/01/272.jpg" pagenum="242"></pb>nent to annex to the other Circumſtances <lb></lb>that have been already ſee down concern<lb></lb>ing this Experiment, That it was made in <lb></lb>Winter, in Weather neither Froſty nor <lb></lb>Rainy, about the change of the Moon, <lb></lb>and at a place whoſe latitude is near about <lb></lb>51<emph type="sup"></emph>d<emph.end type="sup"></emph.end> and a half: For perhaps the force or <lb></lb>preſſure of the Air may vary, according <lb></lb>to the Seaſons of the Year, the tempera<lb></lb>ture of the Weather, the elevation of the <lb></lb>Pole, or the phaſes of the Moon; all, or <lb></lb>even any of them ſeeming capable to al<lb></lb>ter either the heighth or conſiſtence of the <lb></lb>incumbent Atmoſphere: And therefore <lb></lb>it would not be amiſs if this Experiment <lb></lb>were carefully tryd at ſeveral times and <lb></lb>places, with variety of Circumſtances. </s> <s>It <lb></lb>might alſo be try'd with Cylinders of ſe<lb></lb>veral Diameters, exquiſitely fitted with <lb></lb>Suckers, that we might know what pro<lb></lb>portion ſeveral Pillars of the Atmoſphere <lb></lb>bear, to the Weights they are able to ſu<lb></lb>ſtain or lift up; and conſequently, whe<lb></lb>ther the increaſe or decrement of the re<lb></lb>ſiſtance of the ambient Air, can be re<lb></lb>duc'd to any regular proportion to the <lb></lb>Diameters of the Suckers: Theſe, and <lb></lb>divers other ſuch things which may be <lb></lb>try'd with this Cylinder, might moſt of <pb xlink:href="013/01/273.jpg" pagenum="243"></pb>them bemore exactly try'd by the Tori<lb></lb>cellian Experiment, if we could get Tubes <lb></lb>ſo accurately blown and drawn, that the <lb></lb>Cavity were perfectly Cylindrical. </s></p><p type="main"> <s>To dwell upon all the ſeveral Refle<lb></lb>ctions, that a ſpeculative Wit might <lb></lb>make upon this and the foregoing Expe<lb></lb>riment: (I mean the thirty third and thir<lb></lb>ty ſecond, would require almoſt a Vo<lb></lb>lume, whereas our occaſions will ſcarce <lb></lb>allow us time to touch upon three or <lb></lb>four of the chief Inferences that ſeem de<lb></lb>ducible from them, and therefore we ſhall <lb></lb>content our ſelves to point at thoſe <lb></lb>few. </s></p><p type="main"> <s>And firſt, as many other <emph type="italics"></emph>Phænomena<emph.end type="italics"></emph.end><lb></lb>of our Engine, ſo eſpecially, the two <lb></lb>lately mention'd Experiments, ſeem ve<lb></lb>ry much to call in queſtion the receiv'd <lb></lb>Opinion of the Nature or Cauſe of Su<lb></lb>ction. </s> <s>For 'tis true indeed, that when men <lb></lb>ſuck, they commonly uſe ſome manifeſt <lb></lb>endeavour by a peculiar motion of their <lb></lb>Mouthes, Cheſts, and ſome other conſpi<lb></lb>ring parts, to convey to them the body <lb></lb>to be ſuckt in. </s> <s>And hence perhaps they <lb></lb>have taken occaſion, to think that in all <pb xlink:href="013/01/274.jpg" pagenum="244"></pb>Suction there muſt be ſome Endeavour <lb></lb>or motion in the ſucking to attract the <lb></lb>ſucked Body. </s> <s>But in our laſt Experi<lb></lb>ment it appeares not at all how the up<lb></lb>per part of the empty'd Cylinder that re<lb></lb>maines moveleſs all the while, or any <lb></lb>part of it, does at all endeavour to draw <lb></lb>to it the depreſſed Sucker and the an<lb></lb>nex'd weights. </s> <s>And yet thoſe that be<lb></lb>hold the aſcention of the Sucker, without <lb></lb>ſeriouſly conſidering the cauſe of it, doe <lb></lb>readily conclude it to be rayſ'd by ſome<lb></lb>thing that powerfully Sucks or attracts <lb></lb>it, though they ſee not what that may <lb></lb>be or where it lurks. </s> <s>So that it ſeemes <lb></lb>not abſolutely neceſſary to Suction, that <lb></lb>there be in the Body, which is ſaid to ſuck, <lb></lb>an endeavor or motion in order thereun<lb></lb>to, but rather that Suction may be at leaſt <lb></lb>for the moſt part reduc'd to Pulſion, and <lb></lb>its effects aſcrib'd to ſuch a preſſure of <lb></lb>the neighboring air upon thoſe Bodies <lb></lb>(whther aërial, or of other Natures) that <lb></lb>are contiguous to the Body that is ſayd to <lb></lb>attract them, as is ſtronger than that Sub<lb></lb>ſtance which poſſeſſes the cavity of that <lb></lb>ſucking Body is able to reſiſt. </s> <s>To ob<lb></lb>ject here, that it was ſome particles of <lb></lb>Air remaining in the empty'd Cylin-<pb xlink:href="013/01/275.jpg" pagenum="245"></pb>der that attracted this weight to obviate <lb></lb>a <emph type="italics"></emph>Vacuum,<emph.end type="italics"></emph.end> will ſcarce be ſatisfactory; un<lb></lb>leſs it can be cleerly made out by what li<lb></lb>tle hooks, or other grappling Inſtruments, <lb></lb>the internal Air could take hold of the <lb></lb>Sucker; how ſo litle of it obtain'd the <lb></lb>force to lift up ſo great a weight; and why <lb></lb>alſo, upon the letting in of a litle more <lb></lb>Air into one of our evacuated Veſ<lb></lb>ſels, the attraction is, inſtead of being <lb></lb>ſtrengthen'd, much weaken'd, though, <lb></lb>if there were danger of a <emph type="italics"></emph>Vacuum<emph.end type="italics"></emph.end> be<lb></lb>fore, it would remain, notwithſtanding <lb></lb>this ingreſs of a little Air. </s> <s>For that ſtill <lb></lb>there remain'd in the capacity of the ex<lb></lb>hauſted Cylinder ſtore of little rooms, <lb></lb>or ſpaces empty or devoid of Air, may <lb></lb>appear by the great violence wherewith <lb></lb>the air ruſhes in, if any way be open'd to it. <lb></lb></s> <s>And that 'tis not ſo much the decrement <lb></lb>of the <emph type="italics"></emph>Vacuum<emph.end type="italics"></emph.end> within the cavity of the <lb></lb>veſſel that debilitates the attraction, as the <lb></lb>ſpring of the included air (whoſe preſence <lb></lb>makes the decrement) that does it by <lb></lb>reſiſting the preſſure of the external Air, <lb></lb>ſeems probable, partly from the Diſabi<lb></lb>lity of vacuities, whether greater or leſſer, <lb></lb>to reſiſt the preſſure of the Air; and part<lb></lb>ly by ſome of the <emph type="italics"></emph>Phænomena<emph.end type="italics"></emph.end> of our Ex-<pb xlink:href="013/01/276.jpg" pagenum="246"></pb>periments, and particularly by this Cir<lb></lb>cumſtance of the three and Thirtieth, <lb></lb>that the Sucker was by the preſſure of the <lb></lb>Ambient Air impell'd upwards, with its <lb></lb>weight hanging at it, not only when it <lb></lb>was at the bottome of the Cylinder, and <lb></lb>conſequently left a great <emph type="italics"></emph>Vacuum<emph.end type="italics"></emph.end> in the <lb></lb>cavity of it; but when the Sucker had <lb></lb>been already impel'd almoſt to the top of <lb></lb>the Cylinder, and conſequently, when the <lb></lb><emph type="italics"></emph>Vacuum<emph.end type="italics"></emph.end> that remain'd was become very <lb></lb>litle in compariſon of that which preceded <lb></lb>the beginning of the Sucker's aſcention. </s></p><p type="main"> <s>In the next place, theſe Experiments <lb></lb>may teach us, what to judge of the vul<lb></lb>gar Axiom receiv'd for ſo many Ages <lb></lb>as an undoubted Truth in the Peripate<lb></lb>tick Schools; That Nature abhorres <lb></lb>and flys a <emph type="italics"></emph>Vacuum,<emph.end type="italics"></emph.end> and that to ſuch a de<lb></lb>gree, that no humane power (to go no <lb></lb>higher) is able to make one in the Uni<lb></lb>verſe; wherein Heaven and Earth would <lb></lb>change places, and all its other Bodyes <lb></lb>rather act contrary to their own Nature, <lb></lb>than ſuffer it. </s> <s>For, if by a <emph type="italics"></emph>Vacuum<emph.end type="italics"></emph.end> we <lb></lb>will underſtand a place perfectly devoid <lb></lb>of all corporeal Subſtance, it may be in<lb></lb>deed then, as we formerly noted be plau<lb></lb>ſibly enough maintain'd, that there is <pb xlink:href="013/01/277.jpg" pagenum="247"></pb>no ſuch thing in the world; but that the <lb></lb>generality of the Pleniſts, (eſpecially till <lb></lb>of late yeares ſome of them grew more <lb></lb>wary) did not take a <emph type="italics"></emph>Vacuum<emph.end type="italics"></emph.end> in ſo ſtrict <lb></lb>a Senſe, may appear by the Experiments <lb></lb>formerly, and ev'n to this Day imploy'd <lb></lb>by the Deniers of a Vacuum, to prove it <lb></lb>impoſſible that there can be any made. <lb></lb></s> <s>For when they alleadge (for Inſtance) <lb></lb>that when a man ſucks Water through a <lb></lb>long Pipe, that heavy Liquor, contrary <lb></lb>to its Nature, aſcends into the Sucker's <lb></lb>mouth, only, to fill up that room made <lb></lb>by the Dilatation of his Breſt and <lb></lb>Lungs, which otherwiſe will in part be <lb></lb>empty. </s> <s>And when they tell us, that the <lb></lb>reaſon why if a long Pipe exactly <lb></lb>clos'd at one end be fill'd top-ful <lb></lb>of Water, and then inverted, no Liquor <lb></lb>will fall out of the open Orifice; Or, to <lb></lb>uſe a more familiar Example, when they <lb></lb>teach, that the cauſe why in a Gardiner's <lb></lb>watering Pot ſhap'd conically, or like a <lb></lb>Sugar-Loaf fill'd with Water, no Liquor <lb></lb>fals down through the numerous holes <lb></lb>at the bottome, whilſt the Gardiner keeps <lb></lb>his Thumb upon the Orifice of the litle <lb></lb>hole at the top, and no longer, muſt be <lb></lb>that it in the caſe propoſed the Water <pb xlink:href="013/01/278.jpg" pagenum="248"></pb>ſhould deſcend, the Air being unable to <lb></lb>ſucceed it, there would be left at the up<lb></lb>per and deſerted part of the Veſſel a <emph type="italics"></emph>Va<lb></lb>cuum,<emph.end type="italics"></emph.end> that would be avoided if the hole <lb></lb>at the top were open'd. </s> <s>When (I ſay) <lb></lb>they alleadge ſuch Experiments, the <lb></lb>Tendency of them ſeems plainly to im<lb></lb>port, that they mean, by a <emph type="italics"></emph>Vacuum,<emph.end type="italics"></emph.end> any <lb></lb>ſpace here below that is not fill'd with a <lb></lb>viſible body, or at leaſt with Air; though <lb></lb>it be not quite devoy'd of all Body what<lb></lb>ſoever. </s> <s>For why ſhould Nature, out of <lb></lb>her deteſtation of a <emph type="italics"></emph>Vacuum,<emph.end type="italics"></emph.end> make Bo<lb></lb>dies act contrary to their own Tendency, <lb></lb>that a place may be fill'd with Air, if its <lb></lb>being ſo were not neceſſary to the avoi<lb></lb>ding of a <emph type="italics"></emph>Vacuum.<emph.end type="italics"></emph.end></s></p><p type="main"> <s>Taking then a <emph type="italics"></emph>Vacuum<emph.end type="italics"></emph.end> in this vulgar <lb></lb>and obvious ſence, the common opinion <lb></lb>about it ſeems lyable to ſeveral Exce<lb></lb>ptions, whereof ſome of the chief are <lb></lb>ſuggeſted to us by our Engine. </s></p><p type="main"> <s>It will not eaſily then be intelligibly <lb></lb>made out, how hatred or averſation, <lb></lb>which is a paſſion of the Soule, can either <lb></lb>for a <emph type="italics"></emph>Vacuum,<emph.end type="italics"></emph.end> or any other object, be ſup<lb></lb>pos'd to be in Water, or ſuch like inani<lb></lb>mate Body, which cannot be preſum'd <lb></lb>to know when a <emph type="italics"></emph>Vacuum<emph.end type="italics"></emph.end> would enſue; if <pb xlink:href="013/01/279.jpg" pagenum="249"></pb>they did not beſtirre themſelves to pre<lb></lb>vent it, nor to be ſo generous as to act <lb></lb>contrary to what is moſt conducive to <lb></lb>their own particular preſervation for the <lb></lb>publique good of the Univerſe. </s> <s>As much <lb></lb>then of intelligible and probable Truth, <lb></lb>as is contain'd in this Metaphoricall Ex<lb></lb>preſſion, ſeems to amount but to this; <lb></lb>That by the Wiſe Author of Nature <lb></lb>(who is juſtly ſayd to have made all <lb></lb>things in number, weight, and meaſure,) <lb></lb>the Univerſe, and the parts of it, are ſo <lb></lb>contriv'd, that it is as hard to make a <emph type="italics"></emph>Va<lb></lb>cuum<emph.end type="italics"></emph.end> in it, as if they ſtudiouſly conſpir'd <lb></lb>to prevent it. </s> <s>And how far this it ſelfe <lb></lb>may be granted, deſerves to be further <lb></lb>conſider'd. </s></p><p type="main"> <s>For in the next place, our Experiments <lb></lb>ſeem to teach, that the ſuppoſed Averſa<lb></lb>tion of Nature to a <emph type="italics"></emph>Vacuum<emph.end type="italics"></emph.end> is but acci<lb></lb>dental, or in conſequence partly of the <lb></lb>Weight and Fluidity, or, at leaſt, Fluxi<lb></lb>lity of the Bodies here below; and partly, <lb></lb>and perhaps principally, of the Spring of <lb></lb>the air, whoſe reſtleſs endeavor to expand <lb></lb>it ſelfe every way, makes it either ruth <lb></lb>in it ſelfe, or compel the interpos'd bo<lb></lb>dys into all ſpaces, where it finds no grea<lb></lb>ter reſiſtance than it can ſurmount. </s> <s>And <pb xlink:href="013/01/280.jpg" pagenum="250"></pb>that in thoſe motions which are made <emph type="italics"></emph>ob<lb></lb>fugamVacui<emph.end type="italics"></emph.end> (as the common phraſe is) Bo<lb></lb>dys act without ſuch generoſity & Con<lb></lb>ſideration, as is wont to be aſcrib'd to <lb></lb>them, is apparent enough in our 32<emph type="sup"></emph>d<emph.end type="sup"></emph.end> Ex<lb></lb>periment, where the torrent of Air, that <lb></lb>ſeem'd to ſtrive to get into the Empty'd <lb></lb>Receiver, did plainly prevent its own <lb></lb>Deſigne, by ſo impelling the Value, as <lb></lb>to make it ſhut the only Orifice the Air <lb></lb>was to get in at. </s> <s>And if afterwards ei<lb></lb>ther Nature, or the internal Air, had a de<lb></lb>ſigne the external Air ſhould be attra<lb></lb>cted, they ſeem'd to proſecute very un<lb></lb>wiſely by continuing to ſuck the Valve <lb></lb>ſo ſtrongly, when they found that by <lb></lb>that Sucction the Valve it ſelfe could not <lb></lb>be drawn in: Whereas by forbearing to <lb></lb>ſuck, the Valve would by it's own weight <lb></lb>have fall'n down, and ſuffer'd the exclu<lb></lb>ded Air to returne freely, and to fill <lb></lb>again the exhauſted Veſſel. </s></p><p type="main"> <s>And this minds me to take notice of <lb></lb>another deficiency, pointed at by our Ex<lb></lb>periments in the common Doctrine of <lb></lb>thoſe Pleniſts we reaſon with; for many <lb></lb>of thoſe unuſual motions in Bodies, that <lb></lb>are ſayd to be made to eſcape a <emph type="italics"></emph>Vacuum,<emph.end type="italics"></emph.end><lb></lb>ſeem rather made to fill it. </s> <s>For why, <pb xlink:href="013/01/281.jpg" pagenum="251"></pb>to inſtance in our newly mention'd Ex<lb></lb>periment, aſſoon as the Valve was de<lb></lb>preſs'd by the weight we hung at it, <lb></lb>ſhould the Air ſo impetuouſly and copi<lb></lb>ouſly ruſh into the cavity of the Receiver; <lb></lb>if there were before no vacant room there <lb></lb>to receive it? </s> <s>and if there were, then all the <lb></lb>while the Valve kept out the Air, thoſe <lb></lb>litle ſpaces in the Receiver, which the <lb></lb>corpuſcles of that Air afterwards fill'd, <lb></lb>may be concluded to have remain'd em<lb></lb>pty. </s> <s>So that the ſeeming violence, <lb></lb>imploy'd by Nature on the occaſion of <lb></lb>the evacuating of the Veſſel, ſeems to <lb></lb>have come too late to hinder the making <lb></lb>of Vacuities in the Receiver, and only <lb></lb>to have, aſſoon as we permitted, fill'd <lb></lb>up with Air thoſe that were already <lb></lb>made. </s></p><p type="main"> <s>And as for the Care of the Publique <lb></lb>Good of the Univerſe aſcrib'd to dead <lb></lb>and ſtupid Bodies, wee ſhall only de<lb></lb>mand, why in our 19<emph type="sup"></emph>th<emph.end type="sup"></emph.end> Experiment, upon <lb></lb>the Exſuction of the ambient Air, the <lb></lb>Water deſerted the upper half of the <lb></lb>Glaſs-Tube; and did not aſcend to fill <lb></lb>it up, till the external Air was let in upon <lb></lb>it: whereas by its eaſy and ſudden regai<lb></lb>ning that upper part of the Tube, it <pb xlink:href="013/01/282.jpg" pagenum="252"></pb>appear'd both that there was there much <lb></lb>ſpace devoid of Air, and that the Water <lb></lb>might with ſmall or no reſiſtance have <lb></lb>aſcended into it, if it could have done ſo <lb></lb>without the impulſion of the readmitted <lb></lb>Air; which, it ſeems, was neceſſary to <lb></lb>mind the Water of its formerly neglected <lb></lb>Duty to the Univerſe. </s></p><p type="main"> <s>Nay, for ought appeares, ev'n when <lb></lb>the excluded Air, aſſoon as 'twas per<lb></lb>mitted, ruſht violently into our exhau<lb></lb>ſted Receiver, that flowing in of the <lb></lb>Air proceeded rather from the deter<lb></lb>minate Force of the Spring of the <lb></lb>neighbouring Air, then from any endea<lb></lb>vour to fill up, much leſs to prevent va<lb></lb>cuity's. </s> <s>For though when as much Air as <lb></lb>will, is gotten into our Receiver our pre<lb></lb>ſent Opponents take it for granted that <lb></lb>it is full of Air; yet if it be remembred <lb></lb>that when we made our 17<emph type="sup"></emph>th<emph.end type="sup"></emph.end> Experiment <lb></lb>we crouded in more Air to our Receiver <lb></lb>than it uſually holds; and if we alſo con<lb></lb>ſider (which is much more) the Air of <lb></lb>the ſame conſiſtence with that in our <lb></lb>Receiver may in wind guns, as is known, <lb></lb>and as we have try'd, be compreſſed at <lb></lb>leaſt into halfe its wonted room (I ſay at <lb></lb>leaſt, becauſe ſome affirme, that the Air <pb xlink:href="013/01/283.jpg" pagenum="253"></pb>may be thruſt into an 8<emph type="sup"></emph>th<emph.end type="sup"></emph.end>, or a yet ſmaller <lb></lb>part of its ordinary extent) it ſeems ne<lb></lb>ceſſary to admit either a notion of conden<lb></lb>ſation & rarefaction that is not intelligi<lb></lb>ble, or that in the capacity of our Recei<lb></lb>ver when preſum'd to be full of Air, there <lb></lb>yet remain'd as much of ſpace as was ta<lb></lb>ken up by all the aërial corpuſcles unpoſ<lb></lb>ſeſſed by the Air. </s> <s>Which ſeemes plainly, <lb></lb>to infer that the Air that ruſh'd into our <lb></lb>empty'd veſſel did not doe it preciſely <lb></lb>to fill up the Vacuities of it, ſince it left ſo <lb></lb>many unfill'd, but rather was thruſt in by <lb></lb>the preſſure of the contiguous Air; which <lb></lb>as it could not, but be always ready to ex<lb></lb>pand it ſelfe, where it found leaſt reſi<lb></lb>ſtance, ſo was it unable to fill the Recei<lb></lb>ver any more, then until the Air within <lb></lb>was reduc'd to the ſame meaſure of Com<lb></lb>pactneſs with that without. </s></p><p type="main"> <s>We may alſo from our two already of<lb></lb>ten mention'd Experiments further de<lb></lb>duce, that, (ſince Natures hatred of a <lb></lb><emph type="italics"></emph>Vacuum<emph.end type="italics"></emph.end> is but Metaphorical and Ac<lb></lb>cidental, being but a conſequence or re<lb></lb>ſult of the preſſure of the Air and of the <lb></lb>Gravity, and partly alſo of the Fluxility <lb></lb>of ſome other bodies) The power ſhee <lb></lb>makes uſe of to hinder a Vacuum, is not <pb xlink:href="013/01/284.jpg" pagenum="254"></pb>(as we have elſe-where alſo noted) any <lb></lb>ſuch boundleſs thing as men have been <lb></lb>pleas'd to imagine. </s> <s>And the reaſon, why <lb></lb>in the former Experiments, mentioned <lb></lb>in favour of the Pleniſts, Bodies ſeem to <lb></lb>forget their own Natures to ſhun a <emph type="italics"></emph>Va<lb></lb>cuum,<emph.end type="italics"></emph.end> ſeems to be but this; That in the <lb></lb>alleadged caſes the weight of that Wa<lb></lb>ter that was either kept from falling or <lb></lb>impell'd up, was not great enough to <lb></lb>ſurmount the preſſure of the contiguous <lb></lb>Air; which, if it had been, the Water <lb></lb>would have ſubſided, though no Air could <lb></lb>have ſucceeded. </s> <s>For not to repeat that <lb></lb>Experiment of Monſieur <emph type="italics"></emph>Paſchal<emph.end type="italics"></emph.end> (for<lb></lb>merly mention'd to have been try'd in a <lb></lb>Glaſs exceeding 32 Foot) wherein the <lb></lb>inverted Pipe being long enough to con<lb></lb>tain a competent weight of Water, that <lb></lb>Liquor freely ran out at the lower Orifice: <lb></lb>Not to mention this (I ſay) we ſaw in <lb></lb>our nineteenth Experiment, that when <lb></lb>the preſſure of the ambient Air was ſuffi<lb></lb>ciently weaken'd, the Water would fall <lb></lb>out apace at the Orifice even of a ſhort <lb></lb>Pipe, though the Air could not ſucceed <lb></lb>into the room deſerted by it. </s> <s>And it were <lb></lb>not amiſs if tryal were made on the tops <lb></lb>of very high Mountains, to diſcover with <pb xlink:href="013/01/285.jpg" pagenum="255"></pb>what eaſe a <emph type="italics"></emph>Vacuum<emph.end type="italics"></emph.end> could be made near <lb></lb>the confines of the Atmoſphere, where <lb></lb>the Air is probably but light in compari<lb></lb>ſon of what it is here below. </s> <s>But our <lb></lb>preſent (three and thirtieth) Experiment <lb></lb>ſeems to manifeſt, not onely that the <lb></lb>power, exerciſ'd by Nature, to ſhun or re<lb></lb>pleniſh a <emph type="italics"></emph>Vacuum,<emph.end type="italics"></emph.end> is limited, but that it <lb></lb>may be determin'd even to Pounds and <lb></lb>Ounces: Inſomuch that we might ſay, <lb></lb>ſuch a weight Nature will ſuſtain or will <lb></lb>lift up to reſiſt a <emph type="italics"></emph>Vacuum<emph.end type="italics"></emph.end> in our Engine; <lb></lb>but if an Ounce more be added to that <lb></lb>weight, it will ſurmount Her ſo much <lb></lb>magnifi'd deteſtation of Vacuities. </s> <s>And <lb></lb>thus, My Lord, our Experiments may <lb></lb>not onely anſwer thoſe of the Pleniſts, <lb></lb>but enable us to retort their Arguments <lb></lb>againſt themſelves: ſince, if that be true <lb></lb>which they alleadge, that, when Water <lb></lb>falls not down according to its nature, in <lb></lb>a Body wherein no Air can ſucceed to fill <lb></lb>up the place it muſt leave, the ſuſpenſi<lb></lb>on of the Liquor is made <emph type="italics"></emph>Ne detur Vacu<lb></lb>um,<emph.end type="italics"></emph.end> (as they ſpeak) it will follow, that <lb></lb>if the Water can be brought to ſubſide <lb></lb>in ſuch a caſe, that deſerted ſpace may be <lb></lb>deem'd empty, according to their own <lb></lb>Doctrine; eſpecially, ſince Nature (as <pb xlink:href="013/01/286.jpg" pagenum="256"></pb>they would perſwade us) beſtirs her ſelf <lb></lb>ſo mightily to keep it from being de<lb></lb>ſerted. </s></p><p type="main"> <s>I hope I ſhall not need to reminde Your <lb></lb>Lordſhip, that I have all this while been <lb></lb>ſpeaking of a <emph type="italics"></emph>Vacuum,<emph.end type="italics"></emph.end> not in the ſtrict <lb></lb>and Philoſophical ſenſe, but in that more <lb></lb>obvious and familiar one that has been <lb></lb>formerly declar'd. </s></p><p type="main"> <s>And therefore I ſhall now proceed to <lb></lb>obſerve in the laſt place, that our 33<emph type="sup"></emph>d<emph.end type="sup"></emph.end> Ex<lb></lb>periment affords us a notable proof of the <lb></lb>unheeded ſtrength of that preſſure which <lb></lb>is ſuſtain'd by the Corpuſcles of what we <lb></lb>call the free Air, and preſume to be un<lb></lb>compreſſ'd. </s> <s>For, as fluid and yielding a <lb></lb>Body as it is, our Experiment teaches us, <lb></lb>That ev'n in our Climate, and without <lb></lb>any other compreſſion then what is (at <lb></lb>leaſt here below) Natural, or (to ſpeak <lb></lb>more properly) ordinary to it, it bears ſo <lb></lb>ſtrongly upon the Bodies whereunto it is <lb></lb>contiguous, that a Cylinder of this free <lb></lb>Air, not exceeding three Inches in Dia<lb></lb>meter is able to raiſe and carry up a <lb></lb>weight, amounting to between ſixteen <lb></lb>and ſeventeen hundred Ounces. </s> <s>I ſaid, <pb xlink:href="013/01/287.jpg" pagenum="257"></pb>even in our Climate, becauſe that is tem<lb></lb><arrow.to.target n="marg42"></arrow.to.target><lb></lb>perate enough; and as far as my obſer<lb></lb>vations aſſiſt me to conjecture, the Air in <lb></lb>many other more Northern Countries <lb></lb>may be much thicker, and able to ſupport <lb></lb>a greater weight: which is not to be <lb></lb>doubted of, if there be no miſtake in <lb></lb>what is Recorded concerning the <emph type="italics"></emph>Hollan<lb></lb>ders,<emph.end type="italics"></emph.end> that were forc'd by the Ice to Win<lb></lb>ter in <emph type="italics"></emph>Nova Zembla,<emph.end type="italics"></emph.end> namely, That <lb></lb>they found there ſo condenſ'd an Air, that <lb></lb>they could not make their Clock goe, <lb></lb>ev'n by a very great addition to the <lb></lb>weights that were wont to move it. </s></p><p type="margin"> <s><margin.target id="marg42"></margin.target><emph type="italics"></emph>Aere frigi<lb></lb>do exiſtente <lb></lb>tardius mo<lb></lb>ventur Au<lb></lb>tomata <expan abbr="quã">quam</expan> <lb></lb>aere ca<gap></gap>ida, <lb></lb>adco qui<lb></lb>dem ut Au<lb></lb>tomaton <lb></lb>quod Belgæ <lb></lb>in Nova <lb></lb>Zembla a<lb></lb>gentes in æ<lb></lb>dibus ſuis <lb></lb>collocave<lb></lb>runt, omni<lb></lb>no à motis <lb></lb>ceſſaverit <lb></lb>etſi multo <lb></lb>maius toa<lb></lb>dus ei addidiſſent quam antea ferre ſolebat.<emph.end type="italics"></emph.end></s><s> Varenius Geo: Genevat <lb></lb></s> <s>111. Propo: 7. pag. </s> <s>648.</s></p><p type="main"> <s>I ſuppoſe Your Lordſhip will readily <lb></lb>take notice, that I might very eaſily have <lb></lb>diſcourſed much more fully and accuratly <lb></lb>then I have done, againſt the common o<lb></lb>pinion touching Suction, and touching na<lb></lb>tures hatred of a <emph type="italics"></emph>Vacuum.<emph.end type="italics"></emph.end></s><s> But I was willing <lb></lb>to keep my ſelf to thoſe conſiderations <lb></lb>touching theſe matters, that might be ve<lb></lb>rifi'd by our Engine it ſelf, eſpecially, ſince, <lb></lb>as I ſaid at firſt, it would take up too much <lb></lb>time to inſiſt particularly upon all the Re<lb></lb>flections that may be made even upon our <lb></lb>two laſt Experiments. </s> <s>And therefore, <pb xlink:href="013/01/288.jpg" pagenum="258"></pb>paſſing to the next, I ſhall leave it to your <lb></lb>Lordſhip to conſider how far theſe tryals <lb></lb>of ours will either confirm or disfavor <lb></lb>the new Doctrine of ſeveral eminent Na<lb></lb>turaliſts, who teach, That in all motion <lb></lb>there is neceſſarily a Circle of Bodies, as <lb></lb>they ſpeak, moving together; and whe<lb></lb>ther the Circles in ſuch motion be an Ac<lb></lb>cidental or Conſequential thing or no. </s></p><p type="main"> <s>TIs a known thing to thoſe that are con<lb></lb><arrow.to.target n="marg43"></arrow.to.target><lb></lb>verſant in the Hydroſtaticks, That <lb></lb>two Bodies which in the Air are of equal <lb></lb>weight, but of unequal bulk, as Gold, <lb></lb>for inſtance and Iron, being afterwards <lb></lb>weighed in Water, will loſe their <emph type="italics"></emph>Æqui<lb></lb>librium<emph.end type="italics"></emph.end> upon the change of the ambient <lb></lb>Body, ſo that the Gold will ſink lower <lb></lb>then the Iron; which, by reaſon of its <lb></lb>greater bulk, has more Water to lift <lb></lb>or diſplace, that it may ſink. </s> <s>By Analogy <lb></lb>to this Experiment, it ſeem'd probable, <lb></lb>that if two weights did in our Engine <lb></lb>ballance each other, when the Glaſs was <lb></lb>full of Air; upon the exſuction of a <lb></lb>great part of that Air, ſo notable a change <lb></lb>in the conſiſtence of the ambient Body, <pb xlink:href="013/01/289.jpg" pagenum="259"></pb>would make them loſe their <emph type="italics"></emph>Æquili<lb></lb>brium.<emph.end type="italics"></emph.end></s></p><p type="margin"> <s><margin.target id="marg43"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 34.</s></p><p type="main"> <s>But being deſirous at the ſame time to <lb></lb>make a tryal, for a certain Deſign that <lb></lb>needs not here be mention'd, we took <lb></lb>for one of our weights a dry Bladder, <lb></lb>ſtrongly tyed at the Neck, and about <lb></lb>half fill'd with Air (that being a weight <lb></lb>both ſlight, and that would expand it <lb></lb>ſelf in the evacuated Glaſs) and faſtning <lb></lb>that to one part of our formerly menti<lb></lb>on'd exact ballance (which turns with the <lb></lb>32<emph type="sup"></emph>d<emph.end type="sup"></emph.end> part of a Grain) we put a Metalline <lb></lb>counterpoiſe into the oppoſite Scale; and <lb></lb>ſo the two weights being brought to an <lb></lb><emph type="italics"></emph>Æquilibrium,<emph.end type="italics"></emph.end> the ballance was convey'd <lb></lb>into the Receiver, and ſuſpended from the <lb></lb>Cover of it. </s></p><p type="main"> <s>But before we proceed further, we muſt <lb></lb>note, That preſently after the laying on <lb></lb>of the Cover, the Bladder appear'd to <lb></lb>preponderate, whereupon the Scales being <lb></lb>taken out, and reduc'd very near to an <emph type="italics"></emph>Æ<lb></lb>quilibrium,<emph.end type="italics"></emph.end> yet ſo, that a little advantage <lb></lb>remain'd on that ſide to which the Metal<lb></lb>line weight belong'd; they were again let <lb></lb>down into the Receiver, which was pre<lb></lb>ſently made faſt with Plaiſter, and a hot <lb></lb>Iron: Soon after which, before the Pump <pb xlink:href="013/01/290.jpg" pagenum="260"></pb>was employ'd, the Bladder ſeem'd again <lb></lb>a little to preponderate. </s> <s>Afterwards <lb></lb>the Air in the Glaſs being begun to be <lb></lb>drawn out, the Biadder began (according <lb></lb>to the formerly mention'd Obſervations) <lb></lb>to expand it ſelf, and manifeſtly to out<lb></lb>weigh the oppoſite weight, drawing <lb></lb>down the Scale to which it was faſtned <lb></lb>very much beneath the other, eſpecially <lb></lb>when the Air had ſwell'd it to its full ex<lb></lb>tent. </s></p><p type="main"> <s>This done, we very leiſurely let in the <lb></lb>external Air; and obſerv'd, that upon <lb></lb>the flagging of the Bladder, the Scale <lb></lb>whereto it was faſtned, not onely by de<lb></lb>grees return'd to an <emph type="italics"></emph>Æquilibrium<emph.end type="italics"></emph.end> with the <lb></lb>other, but at length was a little out<lb></lb>weighed by it. </s></p><p type="main"> <s>But becauſe we ſuſpected there <lb></lb>might have interven'd ſome unheeded <lb></lb>Circumſtance in this laſt part of the Ex<lb></lb>periment, we would not preſently take <lb></lb>out the Scales, nor meddle with the Co<lb></lb>ver, but leaving things as they were, we <lb></lb>perceiv'd, that after a little while the <lb></lb>Bladder began again to preponderate, and <lb></lb>by degrees to ſink lower and lower for <lb></lb>divers hours; wherefore, leaving the <lb></lb>Veſſel cloſ'd up all night, we repair'd to it <pb xlink:href="013/01/291.jpg" pagenum="261"></pb>next Morning, and found the Bladder <lb></lb>fallen yet lower. </s> <s>As if the very ſubſtance <lb></lb>of it, had imbibed ſome of the moiſture <lb></lb>wherewith the Air (the Seaſon being ve<lb></lb>ry rainy) did then abound: As Lute<lb></lb>ſtrings, which are made likewiſe of the <lb></lb>Membranous parts of Guts, ſtrongly <lb></lb>wreath'd, are known to ſwell ſo much, <lb></lb>oftentimes as to break in rainy and wet <lb></lb>weather. </s> <s>Which conjecture is the more to <lb></lb>beregarded, becauſe congruouſly unto it <lb></lb>one of the company having a little warm'd <lb></lb>the Bladder, found it then lighter then <lb></lb>the oppoſite weight. </s> <s>But this muſt be <lb></lb>look'd upon as a bare conjecture, till we <lb></lb>can gain time to make further tryals about <lb></lb>it. </s> <s>In the mean while we ſhall adde, that <lb></lb>without removing the Scales or the Co<lb></lb>ver of the Receiver, we again cauſ'd the <lb></lb>Air to be drawn out (the weather conti<lb></lb>ing very moiſt) but found not any manifeſt <lb></lb>alteration in the ballance; whether be<lb></lb>cauſe the <emph type="italics"></emph>Æquilibrium<emph.end type="italics"></emph.end> was too far loſt to <lb></lb>let a ſmall change appear, we determine <lb></lb>not. </s></p><p type="main"> <s>But to make the Experiment with a <lb></lb>Body leſs apt to be altered by the tempe<lb></lb>rature of the Air, then was the Bladder; <lb></lb>we brought the Scales again to an <emph type="italics"></emph>Æqui-<emph.end type="italics"></emph.end><pb xlink:href="013/01/292.jpg" pagenum="262"></pb><emph type="italics"></emph>librium<emph.end type="italics"></emph.end> with two weights, whereof the <lb></lb>one was of Lead, the other of Cork. </s> <s>And <lb></lb>having evacuated the Receiver, we obſer<lb></lb>ved, that both upon the exſuction, and <lb></lb>after the return of the Air, the Cork did <lb></lb>manifeſtly preponderate, and much more <lb></lb>a while after the Air had been let in again, <lb></lb>then whilſt it was kept out. </s> <s>Wherefore, <lb></lb>in the room of the Cork, we ſubſtituted <lb></lb>a piece of Char-coal, as leſs likely to im<lb></lb>bibe any moiſture from the Air, but the <lb></lb>event proved much the ſame with that <lb></lb>newly related: So that this Experiment <lb></lb>ſeems more liable to Caſualties then any, <lb></lb>excepting one we have made in our En<lb></lb>gine. </s> <s>And as it is difficult to prevent <lb></lb>them, ſo it ſeems not very eaſie to diſ<lb></lb>cover the cauſes of them, whereof we <lb></lb>ſhall therefore at preſent forbear mention<lb></lb>ing our Conjectures. </s></p><p type="main"> <s>SOme Learned Mathematicians have of <lb></lb><arrow.to.target n="marg44"></arrow.to.target><lb></lb>late ingenioùſly endeavored to reduce <lb></lb>Filters to <emph type="italics"></emph>Siphons;<emph.end type="italics"></emph.end> but ſtill the true cauſe <lb></lb>of the aſcenſion of Water, and other Li<lb></lb>quors, both in <emph type="italics"></emph>Siphons<emph.end type="italics"></emph.end> and in Filtration, <lb></lb>needing (for ought we have yet found) a <lb></lb>clearer Diſcovery and Explication, we <pb xlink:href="013/01/293.jpg" pagenum="263"></pb>were deſirous to try whether or no the <lb></lb>preſſure of the Air might reaſonably be <lb></lb>ſuppoſ'd to have either the principal, or at <lb></lb>leaſt a conſiderable Intereſt in the raiſing <lb></lb>of thoſe Liquors. </s> <s>But becauſe we found <lb></lb>that we could not yet ſo evacuate our Re<lb></lb>ceiver, but that the remaining Air, <lb></lb>though but little in compariſon of the <lb></lb>exhauſted, would be able to impell the <lb></lb>the Water to a greater height then is <lb></lb>uſual in ordinary Filtrations: we reſolved, <lb></lb>inſtead of a Liſt of Cotton, or the like <lb></lb>Filtre, to make uſe of a <emph type="italics"></emph>Siphon<emph.end type="italics"></emph.end> of Glaſs, <lb></lb>delineated in the third Figure, conſiſt<lb></lb>ing of three pieces, two ſtraight, and <lb></lb>the third crooked to joyn them toge<lb></lb>ther; whoſe Junctures were diligently <lb></lb>cloſ'd, that no Air might finde entrance <lb></lb>at them. </s> <s>One of the Legs of this <emph type="italics"></emph>Si<lb></lb>phon<emph.end type="italics"></emph.end> was (as it ſhould be) ſomewhat <lb></lb>longer then the other, and was pervious <lb></lb>at the bottom of it onely, by a hole al<lb></lb>moſt as ſlender as a hair, that the <lb></lb>Water might but very leaſurely drop <lb></lb>out of it, leſt it ſhould all run out <lb></lb>before the Experiment were compleat<lb></lb>ed. </s> <s>The other and ſhorter Leg of <lb></lb>the <emph type="italics"></emph>Siphon<emph.end type="italics"></emph.end> was quite open at the end, <lb></lb>and of the ſame wideneſſe with the <pb xlink:href="013/01/294.jpg" pagenum="264"></pb>reſt of the Pipe, whoſe bore was about <gap></gap>/4 <lb></lb>of an Inch. </s> <s>The whole Siphon made <lb></lb>up of theſe ſeveral pieces put together, <lb></lb>was deſign'd to be about a Foot and a <lb></lb>half long; that the remaining Air, when <lb></lb>the Veſſel was exhauſted after the wont<lb></lb>ed manner, might not be able to impell <lb></lb>the Water to the top of the <emph type="italics"></emph>Siphon;<emph.end type="italics"></emph.end><lb></lb>which being inverted, was fill'd with Wa<lb></lb>ter, and of which the Shorter leg being <lb></lb>let down two or three Inches deep into a <lb></lb>Glaſs Veſſel full of Water, and the up<lb></lb>per parts of it being faſten'd to the inſide <lb></lb>of the Cover of the Receiver, we pro<lb></lb>ceeded to cloſe firſt, and then to empty <lb></lb>the Veſſel. </s></p><p type="margin"> <s><margin.target id="marg44"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 35.</s></p><p type="main"> <s>The effect of the tryal was this, that <lb></lb>till a pretty quantity of Air had been <lb></lb>drawn out, the Water dropp'd freely out <lb></lb>at the lower end of the lower leg of the <lb></lb><emph type="italics"></emph>Siphon,<emph.end type="italics"></emph.end> as if the Experiment had been <lb></lb>performed in the free Air. </s> <s>But afterwards, <lb></lb>the Bubbles (as had been apprehended) <lb></lb>began to diſcloſe themſelves in the Wa<lb></lb>ter, and aſcending to the top of the <emph type="italics"></emph>Si<lb></lb>phon,<emph.end type="italics"></emph.end> imbodyed themſelves there into <lb></lb>one, which was augmented little by little <lb></lb>by the riſing of other bubbles that from <lb></lb>time to time broke into it, but much <pb xlink:href="013/01/295.jpg" pagenum="265"></pb> more by its own dilatation, which en-<lb></lb>creaſ'd proportionably to the exſuction<lb></lb> that was made of the Air out of the Re-<lb></lb>ceiver.</s> <s>So that at length the Water in<lb></lb> the ſhorter Leg of the <emph type="italics"></emph>Siphon<emph.end type="italics"></emph.end>was re-<lb></lb>duc'd partly by the extraction of the am-<lb></lb>bient Air, and partly by the expanſion<lb></lb> of the great Bubble at the upper part of<lb></lb> the <emph type="italics"></emph>Siphon<emph.end type="italics"></emph.end>, to be but about a Foot high,<lb></lb> if ſo much; wherby it came to paſs,<lb></lb> that the courſe of the Water in the <emph type="italics"></emph>Si-<lb></lb>phon<emph.end type="italics"></emph.end> was interrupted, and that which re-<lb></lb>main'd in the longer Leg of it, continu'd<lb></lb> ſuſpended there without dropping any<lb></lb> longer.</s> <s>But upon the turning of the<lb></lb> Stop-cock, the outward Air (being t<lb></lb> into the Receiver) got into the <emph type="italics"></emph>Siphon<emph.end type="italics"></emph.end> by<lb></lb> the little hole at which the Water former-<lb></lb>ly dropt out; and traverſing all the in-<lb></lb>cumbent Cylinder of Water, in the form<lb></lb> of Bubbles, joyn'd it ſelf with that Air<lb></lb> that before poſlongs;eſlongs;'d the top of the <emph type="italics"></emph>Si-<lb></lb>phon<emph.end type="italics"></emph.end>.</s></p> <p type="main"><s>To prevent the inconveniences ariſing<lb></lb> from theſe Bubbles, two Glaſs Pipes, like <lb></lb> the former; were ſo placed; as to termi-<lb></lb>nate together in the midſt of the Belly of<lb></lb> a Glaſs Viol, into whoſe Neck they<lb></lb> were carefully faſtned with Cement; and<pb xlink:href="013/01/296.jpg" pagenum="266"></pb> then both the Viols and the Pipes being<lb></lb> (which was not the not done without difficulty)<lb></lb> totally fill'd with Water, the <emph type="italics"></emph>Siphon<emph.end type="italics"></emph.end><lb></lb> deſcrib'd in the fifth Figure, was plac'd<lb></lb> with its ſhorter Leg in the Glaſs of Wa-<lb></lb>ter, as formerly; and the Experiment be-<lb></lb>ing proſecuted after the ſame manner,<lb></lb> much more Air then formerly was drawn<lb></lb> out, before the Bubbles diſclosing them-<lb></lb>ſelves in the Water were able to diſturb<lb></lb> the Experiment; becauſe that in the ca-<lb></lb>pacity of the Viol there was room enough<lb></lb> for them to ſtretch themſelves, without<lb></lb> depreſſing the Water below the ends of<lb></lb> the Pipes; and, during this time, the<lb></lb> Water continued to drop out of the pro-<lb></lb>pending Leg of the <emph type="italics"></emph>Siphon<emph.end type="italics"></emph.end>.</s> <s>But at<lb></lb> length the Receiverbeing very much em-<lb></lb>pty'd, the paſſage of the Water through<lb></lb> the <emph type="italics"></emph>Siphon<emph.end type="italics"></emph.end>ceaſ'd, the upper ends of the<lb></lb> Pipes beginning to appear a little above<lb></lb> the remaining Water in the Viol, whoſe<lb></lb> dilated Air appear'd likewiſe to preſs<lb></lb> down the Water in the Pipes, and fill the<lb></lb> upper part of them.</s> <s>And hereby the con-<lb></lb>tinuity of the Water, and ſo the Expe-<lb></lb>riment it ſelf being interrupted, we were<lb></lb> invited to let in the air again, which, ac-<lb></lb>cording to its various proportions of<pb xlink:href="013/01/297.jpg" pagenum="267"></pb> preſſure to that of the Air in the Viol<lb></lb> and the Pipes, did for a good while exhi-<lb></lb>bite a pleaſing variety of <emph type="italics"></emph>Phaenomena<emph.end type="italics"></emph.end>,<lb></lb> which we have not now the leiſure to re-<lb></lb>cite.</s> <s>And though upon the whole mat-<lb></lb>ter there ſeem'd little or no cauſe to<lb></lb> doubt, but that, if the Bubbles had not<lb></lb> diſturb'd the Experiment, it would mani-<lb></lb>feſtly enough have appear'd that the<lb></lb> courſe of Water through <emph type="italics"></emph>Siphons<emph.end type="italics"></emph.end> de-<lb></lb>pends upon the preſſure of the Air: yet<lb></lb> we reſolv'd, at our next leiſure and con-<lb></lb>veniency, to try the Experiment again,<lb></lb> with a quantity of Water before freed<lb></lb> from Bubbles by the help of the ſame<lb></lb> Engine.</s></p> <p type="main"><s>This occaſion I have had to take notice<lb></lb> of <emph type="italics"></emph>Siphons<emph.end type="italics"></emph.end>, puts me in minde of an odde<lb></lb> kinde of <emph type="italics"></emph>Siphon<emph.end type="italics"></emph.end> that I cauſ'd to be made<lb></lb> a pretty while ago; and which has been<lb></lb> ſince, by an Ingenious Man of Your ac-<lb></lb>quaintance, communicated to divers o-<lb></lb>thers.</s> <s>This occaſion was this, An emi-<lb></lb>nent Mathematician told me one day, that<lb></lb> ſome inquiſitive French Men (whoſe<lb></lb> Names I know not) had obſerv'd, That,<lb></lb> in caſe one end of a flender and perforated<lb></lb> Pipe of Glaſs be dipt in Water, the Li-<pb xlink:href="013/01/298.jpg" pagenum="268"></pb>quor will aſcend to ſome height in the<lb></lb>Pipe, though held perpendicular to the<lb></lb>plain of the Water.</s> <s>And, to ſatisfie me<lb></lb> that he miſ-related not the Experiment,<lb></lb> he ſoon after brought two or three<lb></lb>ſmall Pipes of Glaſs, which gave me the<lb></lb> opportunity of trying it: though I had<lb></lb>the leſs reaſon to diſtruſt it, becauſe I re-<lb></lb>member I had often in the long and flen-<lb></lb>der Pipes of ſome Weather Glaſſas,<lb></lb> which I had cauſ'd to be made after a<lb></lb>ſomewhat peculiar faſhion, taken notice<lb></lb> of the like aſcenſion of the Liquor,<lb></lb> though (preſuming it might be caſual) I<lb></lb> had made but litllereflection upon it.</s> <s>But<lb></lb> after this tryal, beginning to ſuppoſe, that<lb></lb> though the Water in theſe Pipes that<lb></lb> were brought me, riſe not above a quar-<lb></lb>ter of an Inch, (if near ſo high) yet, if<lb></lb> the Pipes were made flender enough, the<lb></lb> water might riſe to a very much greater<lb></lb> height; I cauſ'd ſeveral of them to be, by<lb></lb> a dexterous Hand, drawn out at the flame<lb></lb> of a Lamp, in one of which that was<lb></lb> almoſt incredibly flender, we found that<lb></lb> the Water asſended (as it were of it ſelf)<lb></lb> five Inches by meaſure, to the no ſmall<lb></lb> wonder of ſome famous Mathematicians,<lb></lb> who were Spectators of ſome of theſe<pb xlink:href="013/01/299.jpg" pagenum="269"></pb>Experiments.</s> <s>And this height the Wa-<lb></lb>ter reach'd to, though the Pipe were held<lb></lb> in as erected a poſture as we could: For if<lb></lb> it were inclin'd, the Water would fill a<lb></lb> greater part of it, though not riſe higher<lb></lb> in it.</s> <s>And we alſo found, that when the<lb></lb> inſide of the Pipe was wetted before-<lb></lb>hand, the Water would riſe much better<lb></lb> then otherways: But we cauſ'd not all<lb></lb> our flender Pipes to be made ſtraight, but<lb></lb> ſome of them crooked, like <emph type="italics"></emph>Siphons<emph.end type="italics"></emph.end>: And<lb></lb> having immerſ'd the ſhorter Leg of one<lb></lb> of theſe into a Glaſs that held ſome fair<lb></lb> Water, we found, as we expected, that<lb></lb> the Water ariſing to the top of the <emph type="italics"></emph>Si-<lb></lb>phon<emph.end type="italics"></emph.end>, though that were high enough, did<lb></lb> of it ſelf run down the longer Leg, and <lb></lb> continue running like an ordinary <emph type="italics"></emph>Siphon<emph.end type="italics"></emph.end>.<lb></lb></s> <s>The cauſe of this aſcenſion of the Wa-<lb></lb>ter, appear'd to all that were preſent ſo<lb></lb> difficult, that I muſt not ſtay to enumerate<lb></lb> the various Conjectures that were made<lb></lb> at it, much leſs to examine them; eſpe-<lb></lb>cially, having nothing but bare Conje-<lb></lb>ctures to ſubſtitute in the room of thoſe<lb></lb> I do not approve.</s> <s>We try'd indeed, by <lb></lb> conveying a very flender Pipe and a ſmall<lb></lb> Veſſel of Water into our Engine, whe-<lb></lb>ther or no the Exſuction of the ambient<pb xlink:href="013/01/300.jpg" pagenum="270"></pb> Air would aſſiſt us to finde the cauſe of<lb></lb> the aſcenſion we have been ſpeaking of:<lb></lb> But though we imploy'd red Wine in-<lb></lb>ſtead of Water, yet we could fearce cer-<lb></lb>tainly perceive thorow ſo much Glaſs, as<lb></lb> was interpoſ'd betwixt our Eyes and the<lb></lb>Liquor, what happen'd in a Pipe ſo flen-<lb></lb>der, that the redneſs of the Wine was<lb></lb> ſcarce ſenſible in it.</s> <s>But as far as we could<lb></lb>diſcern, there happen'd no great altera-<lb></lb>tion to the Liquor: which ſeem'd the leſs<lb></lb> ſtrange, becauſe the Spring of that Air<lb></lb> that might depreſs the Water in the Pipe,<lb></lb> was equally debilitated with that which<lb></lb> remain'd to preſs upon the ſurface of the<lb></lb> Water in the little Glaſs.</s> <s>Wherefore, in<lb></lb> favor of his Ingenious Conjecture who<lb></lb> aſcrib'd the <emph type="italics"></emph>Phaenomenon<emph.end type="italics"></emph.end>, under conſide-<lb></lb>ration to the greater preſſure made upon<lb></lb> the Water by the Air without the Pipe,<lb></lb> then by that within it, (where ſo much of<lb></lb> the Water (conſiſting perhaps of Corpu-<lb></lb>ſcles more pliant to the internal ſurfaces of<lb></lb> the Air) was contiguous to the ſides) it<lb></lb> was ſhown, that in caſe the little Glaſs<lb></lb> Veſſel that held the Water, of which a<lb></lb> part aſcended into the flender Pipe, were<lb></lb> ſo cloſ'd, that a Man might with his mouth<lb></lb> ſuck the Air out of it, the Water would <pb xlink:href="013/01/301.jpg" pagenum="271"></pb> immediately ſubſide in the ſmall Pipe.<lb></lb></s> <s>And this would indeed infer, that it aſ-<lb></lb>cended before onely by the preſſure of<lb></lb> the incumbent Air: But that it may<lb></lb> (how juſtly I know not) be objected,<lb></lb> that preadventure this would not hap-<lb></lb>pen, in caſe the upper ende of the Pipe<lb></lb> were in a <emph type="italics"></emph>Vacuum<emph.end type="italics"></emph.end>: And that 'tis very<lb></lb> probable the Water may ſubſide, not<lb></lb> becauſe the preſſure of the internal Air<lb></lb> is taken off by Exſuction, but by reaſon<lb></lb> of the Spring of the external Air,<lb></lb> which impels the Water it findes in its<lb></lb> way to the Cavity deſerted by the<lb></lb> other Air, and would as well impell<lb></lb> the ſame Water upwards, as make it<lb></lb> ſubſide, if it were not now leiſure to exa-<lb></lb>mine any further this Matter, I ſhall<lb></lb> onely minde Your Lordſhip, that if<lb></lb> You will proſecute this Speculation,<lb></lb> it will be pertinent to finde out likewiſe,<lb></lb> Why the ſurface of Water /as is manifeſt<lb></lb> in Pipes) uſes to be concave, being de-<lb></lb>preſſ'd in the middle, and higher on eve-<lb></lb>ry side? and Why in Quick-ſilver on the<lb></lb> contrary, not onely the ſurface is wont <pb xlink:href="013/01/302.jpg" pagenum="272"></pb> to be very convex, or ſwelling, in the<lb></lb> middle; but if you dip the end of a flen-<lb></lb>der Pipe in it, the ſurface of the Li-<lb></lb>quor (as 'tis call'd) will be lower within<lb></lb> the Pipe, then without.</s> <s>Which <emph type="italics"></emph>Phaeno-<lb></lb>mena<emph.end type="italics"></emph.end>, whether, and how far, they may<lb></lb> be deduc'd from the Figure of the Mer-<lb></lb>curial Corpuſcles, and the Shape of the<lb></lb> Springy Particles of the Air, I willingly<lb></lb> leave to be conſider'd.</s></p> <p type="main"><s><arrow.to.target n="marg441"></arrow.to.target>SEveral ways we have met with pro-<lb></lb>poſ'd, partly by the excellent <emph type="italics"></emph>Galileo<emph.end type="italics"></emph.end>,<lb></lb> and partly by other ingenious Writers,<lb></lb> to manifeſt that the Air is not devoid of<lb></lb> weight; ſome of theſe, require the previ-<lb></lb>ous abſence of the Air to be weighed;<lb></lb> and others, the violent condenſation of it.<lb></lb></s> <s>But if we could lift a pair of Scales above<lb></lb> the Atmoſphere, or place them in a <emph type="italics"></emph>Va-<lb></lb>cuum<emph.end type="italics"></emph.end>, we might there weigh a parcel of<lb></lb> Air it ſelf, as here we do other Bodies in<lb></lb> the Air, becauſe it would there be heavi-<lb></lb>er then that which ſurrounds it, as are<lb></lb>groſſer Bodies we commonly weigh, then<lb></lb> the medium or ambient Air.</s> <s>Where-<lb></lb>fore, though we have above declin'd to<lb></lb> affirm, that our Receiver, when empty-<pb xlink:href="013/01/303.jpg" pagenum="273"></pb>ed, deſerves the name of a true <emph type="italics"></emph>Vacuum<emph.end type="italics"></emph.end>,<lb></lb> and though we cannot yet perfectly free<lb></lb> it from Air it ſelf, yet we thought fit to<lb></lb><lb></lb> try how far the Air would manifeſt its<lb></lb> gravity in ſo thin a medium, as we could<lb></lb> make in our Receiver, by evacuating it.<lb></lb></s> <s>We cauſ'd then to be blown at the Flame<lb></lb> of a Lamp, a Glaſs-bubble of about<lb></lb> the bigneſs of a small Hen egge, and of<lb></lb> an Oval form, ſave that at one end there<lb></lb> was drawn out an exceeding flender Pipe,<lb></lb> that the Bubble might be ſeal'd up, with<lb></lb> as little rarifaction as might be, of the<lb></lb> Air included in the great or ovall Cavi-<lb></lb>ty of it.</s> <s>This Glaſs being ſeal'd, was fa-<lb></lb>ſtened to one of the Scales of the exact<lb></lb> pair of Ballances formerly mention'd;<lb></lb> and being counterpoiſ'd with a weight of<lb></lb> Lead, was convey'd into the Receiver,<lb></lb> and cloſ'd up in it.</s> <s>The Beam appearing<lb></lb> to continue Horizontal, the Pump was ſet<lb></lb> awork, and there ſcarce paſt above two<lb></lb> or three Exſuctions of the Air, before<lb></lb> the Ballance loſt its <emph type="italics"></emph>Aequilibrium<emph.end type="italics"></emph.end>, and<lb></lb> began to incline to that ſide on which<lb></lb> the Bubble was; which, as the Air was<lb></lb> further and further drawn out, did mani-<lb></lb>feſtly more and more preponderate, till<lb></lb> he that pump'd began to grow weary of<pb xlink:href="013/01/304.jpg" pagenum="274"></pb> his Imployment: after which the aire be-<lb></lb>ing leaſurely let in againe, the ſcales by<lb></lb> degrees returned to their former <emph type="italics"></emph>Aequili-<lb></lb>brium<emph.end type="italics"></emph.end>.</s> <s>After that we tooke them out, and<lb></lb> caſting into that ſcale to which the lead<lb></lb> belong'd three quarters of a grain, we<lb></lb> convey'd the ballance into the Recei-<lb></lb>ver, which being cloſed up, and exhau-<lb></lb>ſted as before, we obſerv'd, that as the<lb></lb> aire was drawne out more and more, ſo<lb></lb> the glaſſe bubble came neerer and neer-<lb></lb>er to an <emph type="italics"></emph>Aequilibrium<emph.end type="italics"></emph.end> with the other<lb></lb> weight, till at length the beame was<lb></lb> drawne to hang horizontall; which (as<lb></lb> we had found by another tryall) wee<lb></lb> could not bring it to do, when a quar-<lb></lb>ter of a Graine more was added to<lb></lb> the ſcale, to which the lead belong'd:<lb></lb> though it ſeem'd queſtionleſſe, that if<lb></lb> wee could have perfectly empty'd the<lb></lb> Receiver of the contain'd aire, that in-<lb></lb>cluded, in the bubble would have weigh-<lb></lb>ed above a grain, notwithſtanding its<lb></lb> having been probably ſomewhat Rari-<lb></lb>fy'd by the flame by the help of which,<lb></lb> the bubble was ſeald up.</s> <s>Let us adde,<lb></lb> that on the regreſſe of the excluded<lb></lb> air, the Lead, and the weight caſt into the <pb xlink:href="013/01/305.jpg" pagenum="275"></pb>ſame ſcale, did againe very much pre-<lb></lb>ponderate.</s></p> <p type="margin"><s><margin.target id="marg441"></margin.target><emph type="italics"></emph>Experi-<lb></lb>ment 36.<emph.end type="italics"></emph.end></s></p> <p type="main"><s>We likewiſe convey'd into the Re-<lb></lb>ceiver, the ſame bubble, open'd at<lb></lb> the end of the flender pipe above men-<lb></lb>tioned, but having drawne out the aire,<lb></lb> after the accuſtomed manner, we found<lb></lb> not as before, the bubble to out-weigh<lb></lb> the oppoſite lead, ſo that by the help<lb></lb> of our Engine, we can weigh the Aire,<lb></lb> as we weigh other Bodies, in its na-<lb></lb>turall or ordinary conſiſtence, without<lb></lb> at all condenſing it: Nay, which is re-<lb></lb>markable, having convey'd a Lamb's<lb></lb> bladder about halfe full of Aire into the<lb></lb> Receiver, wee obſerved, that though<lb></lb> upon the drawing out of the ambient<lb></lb>aire the impriſoned Air ſo expended<lb></lb> it ſelf, as to diſtend the Bladder ſo, as to<lb></lb> ſeem ready to break it, yet this rarified<lb></lb> Air did manifeſtly depreſs the Scale<lb></lb> whereunto it was annexed.</s></p> <p type="main"><s>Another thing, we muſt not forget to<lb></lb> mention, that happend to us, whil'ſt we were<lb></lb> making tryals concerning the weight of the<lb></lb> Air; namely, That having once cauſ'd the<pb xlink:href="013/01/306.jpg" pagenum="276"></pb> Pump to be ſomewhat obſtinately ply'd,<lb></lb> to diſcover the better what may be ex-<lb></lb>pected from the thinneſs of the medium<lb></lb> in this Experiment; the Impriſon'd Air<lb></lb> broke its brittle Priſon, and throwing the<lb></lb> greateſt part of it againſt the ſide of the<lb></lb> Receiver, daſh'd it againſt that thick Glaſs<lb></lb> into a multitude of pieces.</s> <s>Which Acci-<lb></lb>dent I mention, partly that it may con-<lb></lb>firm what we deliver'd in our Reflections,<lb></lb> upon the firſt Experiment, where we con-<lb></lb>ſider'd what would probably be done by<lb></lb> the Spring of Air Impriſon'd in ſuch<lb></lb> Glaſſes, in caſe the ballancing preſſure of<lb></lb> the ambient Air were withdrawn; and<lb></lb> partly, that we may thence diſcern of how<lb></lb> cloſe a Texture Glaſs is, ſince ſo very<lb></lb> thin a film of Glaſs (if I may ſo call it)<lb></lb> prov'd ſo impervious to the Air, that it<lb></lb> could not get away through the Pores,<lb></lb> but was forc'd to break the glaſs in pieces<lb></lb> to free it ſelf; and this, notwithſtanding<lb></lb> the time and advantage it had to try to<lb></lb> get out at the Pores.</s> <s>And this I mention,<lb></lb> that neitherour Experiments, nor thoſe<lb></lb> of divers Learned Men, might receive<lb></lb> any prejudice from an Experiment which<lb></lb> I happen'd to make divers years ago, and,<lb></lb> which having been ſo much taken notice<pb xlink:href="013/01/307.jpg" pagenum="277"></pb> of by curious Men, may be drawn to<lb></lb> countenance their erroneous Opinion, who<lb></lb> would fain perſwade us, That Glaſs is<lb></lb> penetrable by Air properly ſo called.</s> <s>Our<lb></lb> Experiment was briefly this: We were<lb></lb> diſtilling a certain ſubſtance, that much a-<lb></lb>bounded with ſubtle Spirits and volatile<lb></lb> Salt, in a ſtrong Earthen-veſſel of an un-<lb></lb>uſual ſhape, to which was luted a large<lb></lb> Receiver, made of the courſer ſort of<lb></lb> Glaſs, (which the Trades-men are wont<lb></lb> to call Green-glaſs) but in our abſence,<lb></lb> the Fire, though it were to be very ſtrong,<lb></lb> was by the negligence or miſtake of thoſe<lb></lb> we appointed to attend it, ſo exceſſively<lb></lb> increaſ'd, that when we came back to the<lb></lb> Fornace we found the Spirituous and Sa-<lb></lb>line Corpuſcles pour'd out (if I may ſo<lb></lb> call it) ſo hot, and ſo copiouſly into the<lb></lb> Receiver, that they made it all opacous,<lb></lb> and more likely to flie in pieces, then fit<lb></lb> to be touch'd.</s> <s>Yet, being curious to ob-<lb></lb>ſerve the effects of a Diſtillation, prſe-<lb></lb>cuted with ſo intenſe and unuſual degree<lb></lb> of heat, we ventur'd to come near, and<lb></lb> obſerv'd among other things, that on the<lb></lb> out-ſide of the Receiver, at a great di-<lb></lb>ſtance from the juncture, there was ſetled<lb></lb> a round whitiſh Spot or two, which at<pb xlink:href="013/01/308.jpg" pagenum="278"></pb>firſt we thought might be ſome ſtain up<lb></lb>on the Glaſs; but after, finding it to <lb></lb>be in divers Qualities like the Oyl, <lb></lb>and Salt of the Concrete we were Di<lb></lb>ſtilling, we began to ſuſpect that the <lb></lb>moſt ſubtle and fugitive parts of the im<lb></lb>petuouſly aſcending Steams, had pene<lb></lb>trated the ſubſtance (as they ſpeak) of <lb></lb>the Glaſs, and by the cold of the am<lb></lb>bient Air were condenſ'd on the ſur<lb></lb>face of it. </s> <s>And though we were ve<lb></lb>ry backward to credit this ſuſpition, and <lb></lb>therefore call'd in an Ingenious Perſon <lb></lb>or two, both to aſſiſt us in the Ob<lb></lb>ſervation, and have Witneſs of its e<lb></lb>vent, we continued a while longer to <lb></lb>watch the eſcape of ſuch unctuous Fumes, <lb></lb>and upon the whole matter unanimouſly <lb></lb>concluded, That all things conſider'd, <lb></lb>the ſubtle parts of the diſtill'd matter <lb></lb>being violently agitated, by the exceſ<lb></lb>ſive heat had paſſ'd through the Pores <lb></lb>of the Glaſs, widen'd by the ſame heat. <lb></lb></s> <s>But this having never happen'd but <lb></lb>once in any of the Diſtillations we have <lb></lb>either made or ſeen, though theſe be <lb></lb>not a few, it is much more reaſonable <lb></lb>to ſuppoſe, that the perviouſneſs of <lb></lb>our Receiver to a Body much more <pb xlink:href="013/01/309.jpg" pagenum="279"></pb>ſubtle then Air, proceeded partly from <lb></lb>the looſer Texture of that particular <lb></lb>parcel of Glaſs the Receiver was made <lb></lb>of (for Experience has taught us, that <lb></lb>all Glaſs is not of the ſame compact<lb></lb>neſs and ſolidity) and partly from the <lb></lb>enormous heat, which, together with <lb></lb>the vehement agitation of the pene<lb></lb>trant Spirits, open'd the Pores of the <lb></lb>Glaſs; then to imagine that ſuch a <lb></lb>ſubſtance as Air, ſhould be able to per<lb></lb>meate the Body of Glaſs contrary to <lb></lb>the teſtimony of a thouſand Chymical <lb></lb>and Mechanical Experiments, and of <lb></lb>many of thoſe made in our Engine, e<lb></lb>ſpecially that newly recited: Nay, by <lb></lb>our fifth Experiment it appears, that <lb></lb>a thin Bladder will not at its Pores <lb></lb>give paſſage even to rarified Air. </s> <s>And <lb></lb>on this occaſion we will annex an Ex<lb></lb>periment, which has made ſome of <lb></lb>thoſe we have acquainted with it, <lb></lb>doubt, whether the Corpuſcles of the <lb></lb>Air be not leſſe ſubtle then thoſe of <lb></lb>Water. </s></p><p type="main"> <s>But without examining here the <lb></lb>reaſonableneſſe of that doubt, we will <lb></lb>proceed to recite the Experiment it ſelf, <lb></lb>which ſeems to teach, That though Air, <pb xlink:href="013/01/310.jpg" pagenum="280"></pb>when ſufficiently compreſſ'd, may per<lb></lb>chance get entrance into narrower holes <lb></lb>and crannies then Water; yet unleſs the <lb></lb>Air be forc'd in at ſuch very little holes, <lb></lb>it will not get in at them, though they <lb></lb>may be big enough to let Water paſs <lb></lb>through them. </s></p><p type="main"> <s>The Experiment then was this: I took <lb></lb>a fair Glaſs <emph type="italics"></emph>Siphon,<emph.end type="italics"></emph.end> the lower end of <lb></lb>whoſe longeſt Leg was drawn by degrees <lb></lb>to ſuch a ſlenderneſs, that the Orifice, at <lb></lb>which the Water was to fall out, would <lb></lb>hardly admit a very ſmall Pin: This <emph type="italics"></emph>Si<lb></lb>phon<emph.end type="italics"></emph.end> being inverted, the matter was ſo <lb></lb>order'd, that a little Bubble of Air was <lb></lb>intercepted in the ſlendereſt part of the <lb></lb><emph type="italics"></emph>Siphon,<emph.end type="italics"></emph.end> betwixt the little hole newly men<lb></lb>tion'd, and the incumbent Water, upon <lb></lb>which, it came to paſs, that the Air be<lb></lb>ing not to be forc'd through ſo narrow a <lb></lb>paſſage, by ſo light a Cylinder of Water, <lb></lb>though amounting to the length of divers <lb></lb>Inches, as lean'd upon it, hinder'd the <lb></lb>further Efflux of the Water, as long as I <lb></lb>pleaſ'd to let it ſtay in that narrow place: <lb></lb>whereas, when by blowing a little at the <lb></lb>wider end of the <emph type="italics"></emph>Siphon,<emph.end type="italics"></emph.end> that little par<lb></lb>cel of Air was forc'd out with ſome Wa<lb></lb>ter, the remaining Water, that before <pb xlink:href="013/01/311.jpg" pagenum="281"></pb>continu'd ſuſpended, began freely to drop <lb></lb>down again as formerly. </s> <s>And if you <lb></lb>take a Glaſs Pipe, whether it be in the <lb></lb>form of a <emph type="italics"></emph>Siphon,<emph.end type="italics"></emph.end> or no, that being for <lb></lb>the moſt part of the thickneſs of a Mans <lb></lb>Finger, is yet towards one end ſo ſlen<lb></lb>der, as to terminate in a hole almoſt as <lb></lb>ſmall as a Horſe-hair; and if you fill this <lb></lb>Pipe with Water, you will finde that Li<lb></lb>quor to drop down freely enough tho<lb></lb>row the ſlender Extream: But if you then <lb></lb>invert the Pipe, you will finde that the <lb></lb>Air will not eaſily get in at the ſame hole <lb></lb>through which the Water paſſ'd. </s> <s>For in <lb></lb>the ſharp end of the Pipe, ſome Inches <lb></lb>of Water will remain ſuſpended, which <lb></lb>'tis probable would not happen, if the <lb></lb>Air could get in to ſucceed it, ſince if the <lb></lb>hole were a little wider, the Water would <lb></lb>immediatly ſubſide. </s> <s>And though it be <lb></lb>true, that if the Pipe be of the length of <lb></lb>many Inches, a great part of the Wa<lb></lb>ter will run down at the wider Orifice, yet <lb></lb>that ſeems to happen for ſome other rea<lb></lb>ſon, then becauſe the Air ſucceeds it at <lb></lb>the upper and narrow Orifice, ſince all the <lb></lb>ſlender part of the Pipe, and perhaps <lb></lb>ſome Inches more, will continue full of <lb></lb>Water. </s></p><pb xlink:href="013/01/312.jpg" pagenum="282"></pb><p type="main"> <s>And on this occaſion I remember, that <lb></lb>whereas it appears by our fifth Experi<lb></lb>ment, That the Aërial Corpuſcles (ex<lb></lb>cept perhaps ſome that are extraordinari<lb></lb>ly fine) will not paſſe thorow the Pores <lb></lb>of a Lambs Bladder, yet Particles of Wa<lb></lb>ter will, as we have long ſince obſerv'd, <lb></lb>and as may be eaſily try'd, by very cloſe<lb></lb>ly tying a little <emph type="italics"></emph>Alcalizate<emph.end type="italics"></emph.end> Salt (we uſ'd <lb></lb>the Calx of Tartar, made with Nitre) <lb></lb>in a fine Bladder, and dipping the lower <lb></lb>end of the Bladder in Water; for if you <lb></lb>hold it there for a competent while, you <lb></lb>will finde that there will ſtrain thorow the <lb></lb>Pores of the Bladder Water enough to <lb></lb>diſſolve the Salt into a Liquor. </s></p><p type="main"> <s>But I ſee I am ſlipt into a Digreſſion, <lb></lb>wherefore I will not examine, whether, <lb></lb>the Experiment I have related, proceed<lb></lb>ed from hence, That the ſpringy Texture <lb></lb>of the Corpuſcles of the Air, makes <lb></lb>them leſs apt to yield and accommodate <lb></lb>themſelves eaſily to the narrow Pores of <lb></lb>Bodies, then the more flexible Particles <lb></lb>of Water; or whether it may more pro<lb></lb>babiy be aſcrib'd to ſome other Cauſe. <lb></lb></s> <s>Nor will I ſtay to conſider how far we may <lb></lb>hence be aſſiſted to gheſs at the cauſe of <lb></lb>the aſcenſion of Water in the ſlender <pb xlink:href="013/01/313.jpg" pagenum="283"></pb>Pipes and <emph type="italics"></emph>Siphons<emph.end type="italics"></emph.end> formerly mention'd, <lb></lb>but will return to our Bubble; and take <lb></lb>notice, That we thought fit alſo to en<lb></lb>deavor to meaſure the capacity of the <lb></lb>Bubble we had made uſe of, by filling <lb></lb>it with Water, that we might the better <lb></lb>know how much Water anſwered in <lb></lb>weight to 3/4 of a Grain of Air, but not<lb></lb>withſtanding all the diligence that was <lb></lb>uſed to preſerve ſo brittle a Veſſel, it <lb></lb>broke before we could perfect what we <lb></lb>were about, and we were not then pro<lb></lb>vided of another Bubble fit for our <lb></lb>turn. </s></p><p type="main"> <s>The haſte I was in, My Lord, when I <lb></lb>ſent away the laſt Sheet, made me forget <lb></lb>to take notice to you of a Problem that <lb></lb>occurr'd to my thoughts, upon the oc<lb></lb>caſion of the ſlow breaking of the Glaſs <lb></lb>Bubble in our evacuated Receiver. </s> <s>For <lb></lb>it may ſeem ſtrange, ſince by our ſixth <lb></lb>Experiment it appears, that the Air, when <lb></lb>permitted, will by its own internal Spring <lb></lb>expand it ſelfe twice as much as <emph type="italics"></emph>Mer<lb></lb>ſennus<emph.end type="italics"></emph.end> was able to expand it, by the <lb></lb>heat even of a candent <emph type="italics"></emph>Æolipile:<emph.end type="italics"></emph.end> Yet <lb></lb>the <emph type="italics"></emph>Elater<emph.end type="italics"></emph.end> of the Air was ſcarce able to <lb></lb>break a very thin Glaſs Bubble, and ut-<pb xlink:href="013/01/314.jpg" pagenum="284"></pb>terly unable to break one ſomewhat thic<lb></lb>ker, within whoſe cavity it was impri<lb></lb>ſon'd; whereas Air pent up and agitated <lb></lb>by heat is able to perform ſo much more <lb></lb>conſiderable effects, that (not to mention <lb></lb>thoſe of Rarefaction that are more obvi<lb></lb>ous) the Learned Jeſuit <emph type="italics"></emph>Cabæus<emph.end type="italics"></emph.end> (he that <lb></lb><arrow.to.target n="marg45"></arrow.to.target><lb></lb>writ of the Load-ſtone) relates, That he <lb></lb>ſaw a Marble Pillar (ſo vaſt, that three <lb></lb>men together with diſplay'd arms could <lb></lb>not imbrace it, and that 1000 Yoke of <lb></lb>Oxen drawing it ſeveral ways with all <lb></lb>their ſtrength, could not have torn it <lb></lb>aſſunder) quite broken off in the midſt, <lb></lb>by reaſon of ſome Wood, which hap<lb></lb>pening to be burnt juſt by the Pillar, the <lb></lb>heat proceeding from the neighboring <lb></lb>Fire, ſo rarified ſome Air or Spirituous <lb></lb>Matter which was ſhut up in the cavities <lb></lb>of the Marble, that it broke through the <lb></lb>ſolid Body of the Stone to obtain room <lb></lb>to expand it ſelf. </s></p><p type="margin"> <s><margin.target id="marg45"></margin.target><emph type="italics"></emph><gap></gap>: Nicoi: <lb></lb>Cab: lib:<emph.end type="italics"></emph.end> 4. <lb></lb><emph type="italics"></emph>Meteo<gap></gap> A<lb></lb><gap></gap><emph.end type="italics"></emph.end></s></p><p type="main"> <s>I remember I have taken notice that <lb></lb>probably the reaſon why the included Air <lb></lb>did not break the hermetically ſeal'd Bub<lb></lb>bles that remain'd intire in our emptyed <lb></lb>Receiver, was, That the Air, being ſome<lb></lb>what rarefied by the Flame imploy'd to <lb></lb>cloſe the Glaſs, its Spring, upon the re-<pb xlink:href="013/01/315.jpg" pagenum="285"></pb>ceſs of the heat, grew weaker then before. <lb></lb></s> <s>But though we reject not that gheſs, yet <lb></lb>it will not in the preſent caſe ſerve the <lb></lb>turn, becauſe that much ſmaller Glaſs <lb></lb>bubbles exactly cloſ'd, will, by the in<lb></lb>cluded Air (though agitated but by the <lb></lb>heat of a very moderate Fire) be made <lb></lb>to fly in pieces. </s> <s>Whether we may be <lb></lb>aſſiſted to ſalve this Problem, by conſi<lb></lb>dering that the heat does from within ve<lb></lb>hemently agitate the Corpuſcles of the <lb></lb>Air, and adde its aſſiſtance to the Spring <lb></lb>they had before, I ſhall not now examine: <lb></lb>ſince I here but propoſe a Problem, and <lb></lb>that chiefly that by this memorable Story <lb></lb>of <emph type="italics"></emph>Cabæus,<emph.end type="italics"></emph.end> notice may be taken of the <lb></lb>prodigious power of Rarefaction, which <lb></lb>hereby appears capable of performing <lb></lb>ſtranger things then any of our Experi<lb></lb>ments have hitherto aſcrib'd to it. </s></p><p type="main"> <s>We ſhould hence, My Lord, imme<lb></lb>diatly proceed to the next Experiment, <lb></lb>but that we think it fit, on this occaſion, <lb></lb>to acquaint You with what ſome former <lb></lb>tryals (though not made in our Engine) <lb></lb>have taught us, concerning what we <lb></lb>would have diſcover'd by the newly <lb></lb>mention'd Bubble that broke. </s> <s>And this <lb></lb>the rather, becauſe (a great part of this <pb xlink:href="013/01/316.jpg" pagenum="286"></pb>letter ſuppoſing the gravity of the Aire) <lb></lb>it will not be impertinent to determine <lb></lb>more particularly then hitherto we have <lb></lb>done, what gravity we aſcribe to it. </s></p><p type="main"> <s>We tooke then an <emph type="italics"></emph>Æolipile<emph.end type="italics"></emph.end> made of <lb></lb>copper, weighing ſix ounces, five drachms, <lb></lb>and eight and forty graines: this being <lb></lb>made as hot as we durſt make it, (for feare <lb></lb>of melting the mettle, or at leaſt the So<lb></lb>dar) was removed from the fire and im<lb></lb>mediately ſtopped with hard wax that no <lb></lb>Aire at all might get in at the little <lb></lb>hole wont to be left in <emph type="italics"></emph>Æolipiles<emph.end type="italics"></emph.end> for the <lb></lb>fumes to iſſue out at: Then the <emph type="italics"></emph>Æolipile<emph.end type="italics"></emph.end><lb></lb>being ſuffer'd leaſurely to coole was again <lb></lb>weighed together with the wax that ſtopt <lb></lb>it, and was found to weigh (by reaſon of <lb></lb>the additionall weight of the wax) ſix <lb></lb>ounces, ſixe drachmes, and 39 graines. <lb></lb></s> <s>Laſtly, the wax being perforated without <lb></lb>taking any of it out of the Scale, the <lb></lb>externall Aire was ſuffered to ruſh in <lb></lb>(which it did with ſome noyſe) and then <lb></lb>the <emph type="italics"></emph>Æolipile<emph.end type="italics"></emph.end> and wax, being againe <lb></lb>weighed amounted to ſix ounces, ſix <lb></lb>drachmes, and 50. graines. </s> <s>So that the <lb></lb><emph type="italics"></emph>Æolipile<emph.end type="italics"></emph.end> freed as farre as our fire could <lb></lb>free it, from it's Aire, weighed leſſe then <pb xlink:href="013/01/317.jpg" pagenum="287"></pb>it ſelfe when repleniſhed with Air, full <lb></lb>eleven graines. </s> <s>That is, the Air contain<lb></lb>able within the cavity of the <emph type="italics"></emph>Æolipile<emph.end type="italics"></emph.end> a<lb></lb>mounted to eleven graines and ſomewhat <lb></lb>more; I ſay ſomewhat more, becauſe of <lb></lb>the particles of the Air, that were not <lb></lb>driven by the fire out of the <emph type="italics"></emph>Æolipile.<emph.end type="italics"></emph.end><lb></lb>And by the way (if there be no miſtake <lb></lb>in the obſervations of the diligent <emph type="italics"></emph>Mer<lb></lb>ſennus<emph.end type="italics"></emph.end>) it may ſeeme ſtrange that it ſhould <lb></lb>ſo much differ from 2. or 3. of ours; in <lb></lb>none of which we could rarifie the Air in <lb></lb>our Æ<emph type="italics"></emph>olipile<emph.end type="italics"></emph.end> (though made red hot almoſt <lb></lb>all over, and ſo immediately plung'd into <lb></lb>cold water) to halfe that degree which he <lb></lb>mentions, namely to 70. times it's natu<lb></lb>rall extent, unleſſe it were that the <emph type="italics"></emph>Æo<lb></lb>lipile<emph.end type="italics"></emph.end> he imploy'd was able to ſuſtaine <lb></lb>a more vehement heat then ours (which <lb></lb>yet we kept in ſo great an one, that once <lb></lb>the ſoder melting, it fell aſunder into the <lb></lb>two Hemiſpheres it conſiſts of.) </s></p><p type="main"> <s>The fore-mentioned way of weighing <lb></lb>the Air by the help of an <emph type="italics"></emph>Æolipile,<emph.end type="italics"></emph.end> ſeems <lb></lb>ſomewhat more exact then that which <lb></lb><emph type="italics"></emph>Merſennus<emph.end type="italics"></emph.end> uſed, In that in ours the <emph type="italics"></emph>Æoli<lb></lb>pile<emph.end type="italics"></emph.end> was not weighed, till it was cold; <lb></lb>whereas in his, being weighed red hot, it <pb xlink:href="013/01/318.jpg" pagenum="288"></pb>ſubject to looſe of it's ſnbſtance in the <lb></lb>cooling, for (as we have elſewhere noted <lb></lb>on another occaſion) Copper heated red <lb></lb>hot is wont in the cooling to throw off <lb></lb>little thin ſcales in ſuch plenty, that having <lb></lb>purpoſely watcht a Copper <emph type="italics"></emph>Æolipile<emph.end type="italics"></emph.end> du<lb></lb>ring its refrigeration, we have ſeen the <lb></lb>place round about it almoſt covered with <lb></lb>thoſe little ſcales it had every way ſcat<lb></lb>ter'd: which, however they amount not <lb></lb>to much, ought not to be over-looked, <lb></lb>when 'tis ſo light a body as Air, that is <lb></lb>to be weighed. </s> <s>We will not examine, <lb></lb>whether the Æ<emph type="italics"></emph>olipile<emph.end type="italics"></emph.end> in cooling may not <lb></lb>receive ſome little increment of weight, <lb></lb>either from the vapid or ſaline Steames <lb></lb>that wander up and downe in the Air: But <lb></lb>we will rather mention, that (for the grea<lb></lb>ter exactneſſe) we imployed to weigh our <lb></lb><emph type="italics"></emph>Æolipile,<emph.end type="italics"></emph.end> both when fill'd onely with Air <lb></lb>and when repleniſht with Water, a paire <lb></lb>of ſcales that would turne (as they ſpeak) <lb></lb>with the fourth part of a grain. </s></p><p type="main"> <s>As to the proportion of weight be<lb></lb>twixt Air and Water, ſome learned men <lb></lb>have attempted it by wayes ſo unaccurate <lb></lb>that they ſeeme to have much miſtaken <lb></lb>it. </s> <s>For (not to mention the improbable <lb></lb>accounts of <emph type="italics"></emph>Kepler<emph.end type="italics"></emph.end> and others.) The lear-<pb xlink:href="013/01/319.jpg" pagenum="289"></pb>ned and diligent <emph type="italics"></emph>Ricciolus,<emph.end type="italics"></emph.end> having pur<lb></lb>poſely endeavoured to inveſtigate this <lb></lb>proportion by meanes of a thin blad<lb></lb>der, eſtimates the weight of the Air to <lb></lb>that of the Water to be as one to ten <lb></lb>thouſand, or thereabouts. </s> <s>And indeed I re<lb></lb>member that having formerly, on a cer<lb></lb>tain occaſion, weighed a large bladder full <lb></lb>of Air, and found it when the Air was all <lb></lb>ſqueeſed out, to have contained fourteen <lb></lb>graines of Air. </s> <s>I found the ſame bladder <lb></lb>afterwards fill'd with water to containe <lb></lb>very neer 14. pound of that liquor: accor<lb></lb>ding to which account, the proportion of <lb></lb>Air to Water was almoſt as a graine to a <lb></lb>pound, that is, as one to above 7600. To <lb></lb>this we may adde, that on the other ſide, <lb></lb><emph type="italics"></emph>Galileo<emph.end type="italics"></emph.end> himſelfe uſing another, but an un<lb></lb>accurate way too, defined the Air to be <lb></lb>in weight to Water, but as one to 4. hun<lb></lb>dred. </s> <s>But the way formerly propoſed of <lb></lb>weighing the Air by an Æ<emph type="italics"></emph>olipile,<emph.end type="italics"></emph.end> ſeemes <lb></lb>by great oddes more exact; and (as farre <lb></lb>as we could gheſſe) ſeemed to agree well <lb></lb>enough with the experiment made in our <lb></lb>Receiver. </s> <s>Wherefore it will be beſt to <lb></lb>truſt our Æ<emph type="italics"></emph>olipile<emph.end type="italics"></emph.end> in the enquiry we are a<lb></lb>bout, and according to our obſervations <lb></lb>the water it contained amounting to one <pb xlink:href="013/01/320.jpg" pagenum="290"></pb>and twenty ounces and an halfe, and as <lb></lb>much Air as was requiſite to fill it weigh<lb></lb>ing eleven graines, the proportion in gra<lb></lb>vity of Air to Water of the ſame bulk <lb></lb>will be as one to 938. And though we <lb></lb>could not fill the Æ<emph type="italics"></emph>olipile<emph.end type="italics"></emph.end> with water, ſo <lb></lb>exactly as we would, yet in regard we <lb></lb>could not either as perfectly as we would, <lb></lb>drive the Air out of it by heat; we think <lb></lb>the proportion may well enough hold: <lb></lb>but thoſe that are delighted with round <lb></lb>numbers (as the phraſe is) will not be <lb></lb>much miſtaken if they reckon water to be <lb></lb>neere a thouſand times heavier than Air. <lb></lb></s> <s>And (for further proof that we have made <lb></lb>the proportion betwixt theſe two bodies <lb></lb>rather greater then leſſer then indeed it is; <lb></lb>and alſo to confirme our former obſerva<lb></lb>tion of the weight of the Air) we will adde, <lb></lb>That, having another time put ſome Wa<lb></lb>ter into the Æ<emph type="italics"></emph>olipile<emph.end type="italics"></emph.end> before we ſet it on <lb></lb>the fire, that the copious vapours of the <lb></lb>rarefied liquor might the better drive out <lb></lb>the Air, we found, upon try all carefully <lb></lb>made, that when the Æ<emph type="italics"></emph>olipile<emph.end type="italics"></emph.end> was refrige<lb></lb>rated, and the included vapours were by <lb></lb>the cold turned againe into water (which <lb></lb>could not have happen'd to the Air, that <lb></lb>the preceeding Steams expell'd) the Air, <pb xlink:href="013/01/321.jpg" pagenum="291"></pb>when it was let in, increaſ'd the weight of <lb></lb>the <emph type="italics"></emph>Æolipile<emph.end type="italics"></emph.end> as much as before, namely, <lb></lb>Eleven Grains; though there were alrea<lb></lb>dy in it twelve Drachmes and a half, be<lb></lb>ſides a couple of Grains of Water, which <lb></lb>remain'd of that we had formerly put in<lb></lb>to it to drive out the Air. </s></p><p type="main"> <s><emph type="italics"></emph>Merſennus<emph.end type="italics"></emph.end> indeed tells us, that by his <lb></lb>account Air is in weight to Water, as 1 to <lb></lb>1356. And adds, that we may, without <lb></lb>any danger, believe that the gravity of <lb></lb>Water to that of Air of a like bulk, is <lb></lb>not leſs then of 1300 to 1. And conſe<lb></lb>quently, that the quantity of Air to a <lb></lb>quantity of Water equiponderant there<lb></lb>to, is as 1300 to 1. But why we ſhould <lb></lb>relinquiſh our own carefully repeated try<lb></lb>als, I ſee not. </s> <s>Yet I am unwilling to re<lb></lb>ject thoſe of ſo accurate and uſeful a Wri<lb></lb>ter: And therefore ſhall propoſe a way <lb></lb>of reconciling our differing Obſervations, <lb></lb>by preſenting, that the diſcrepance be<lb></lb>tween them may probably ariſe from the <lb></lb>differing conſiſtence of the Air at <emph type="italics"></emph>London<emph.end type="italics"></emph.end><lb></lb>and at <emph type="italics"></emph>Paris:<emph.end type="italics"></emph.end> For our Air being more cold <lb></lb>and moiſt, then that which Your Lord<lb></lb>ſhip now breaths, may be ſuppoſ'd alſo <lb></lb>to be a fourth or fifth part more heavy. </s> <s>I <lb></lb>leave it to be conſider'd, whether it be of <pb xlink:href="013/01/322.jpg" pagenum="292"></pb>any moment that our Obſervations were <lb></lb>made in the midſt of Winter, whereas his <lb></lb>were perhaps made in ſome warmer time <lb></lb>of the Year. </s> <s>But I think it were not a<lb></lb>miſs that, by the method formerly pro<lb></lb>poſ'd, the gravity of the Air were ob<lb></lb>ſerv'd both in ſeveral Countries, and in <lb></lb>the ſame Country, in the ſeveral Seaſons <lb></lb>of the Year and differing Temperatures of <lb></lb>the Weather. </s> <s>And I would give ſome<lb></lb>thing of value to know the weight of ſuch <lb></lb>an <emph type="italics"></emph>Æolipile<emph.end type="italics"></emph.end> as ours full of air in the midſt <lb></lb>of Winter in <emph type="italics"></emph>Nova Zembla,<emph.end type="italics"></emph.end> if that be <lb></lb>true which we formerly took notice of, <lb></lb>namely, That the <emph type="italics"></emph>Hollanders,<emph.end type="italics"></emph.end> who Win<lb></lb>tered there, found that Air ſo thick that <lb></lb>their Clock would not go. </s></p><p type="main"> <s>If Your Lordſhip ſhould now ask me, <lb></lb>if I could not by the help of theſe, and <lb></lb>our other Obſervations, decide the Con<lb></lb>troverſies of our Modern Mathematici<lb></lb>ans about the height of the Air or Atmo<lb></lb>ſphere, by determining how high it doth <lb></lb>indeed reach: I ſhould anſwer, That <lb></lb>though it ſeems eaſie enough to ſhew that <lb></lb>divers Famous and Applauded Writers <lb></lb>have been miſtaken in aſſigning the heigth <lb></lb>of the Atmoſphere: Yet it ſeems very <lb></lb>difficult preciſely to define of what height <pb xlink:href="013/01/323.jpg" pagenum="293"></pb>it is. </s> <s>And becauſe we have hitherto but <lb></lb>lightly touch'd upon a matter of ſuch im<lb></lb>portance, we preſume it wil not be thought <lb></lb>impertinent, upon this occaſion, to annex <lb></lb>ſomething towards the Elucidation of <lb></lb>it. </s></p><p type="main"> <s>What we have already try'd and newly <lb></lb>ſet down, allows us to take it for granted, <lb></lb>that (at leaſt about <emph type="italics"></emph>London<emph.end type="italics"></emph.end>) the propor<lb></lb>tion of gravity betwixt Water and Air, <lb></lb>of equal bulk, is as of a thouſand to <lb></lb>one. </s></p><p type="main"> <s>The next thing therefore that we are <lb></lb>to enquire after, in order to our preſent <lb></lb>deſign, is the difference in weight betwixt <lb></lb>Water and Quick-ſilver: And though <lb></lb>this hath been defin'd already by the Il<lb></lb>luſtrious <emph type="italics"></emph>Verulam,<emph.end type="italics"></emph.end> and ſome other inqui<lb></lb>ſitive Perſons, that have compar'd the <lb></lb>weight of ſeveral Bodies, and caſt their <lb></lb>Obſervations into Tables, yet we ſhall <lb></lb>not ſcruple to annex our own tryals about <lb></lb>it: Partly, becauſe we finde Authors <lb></lb>conſiderably to diſ-agree; partly, becauſe <lb></lb>we uſ'd exacter Scales, and a ſomewhat <lb></lb>more wary method then others ſeem to <lb></lb>have done: And partly alſo, becauſe ha<lb></lb>ving proſecuted our inquiry by two or <lb></lb>three ſeveral ways; the ſmall difference <pb xlink:href="013/01/324.jpg" pagenum="294"></pb>between the events may aſſure us that we <lb></lb>were not much miſtaken. </s></p><p type="main"> <s>We took then a Glaſs Pipe, of the <lb></lb>form of an inverted <emph type="italics"></emph>Siphon,<emph.end type="italics"></emph.end> whoſe ſhape <lb></lb>is delineated in the ſixteenth Figure: And <lb></lb>pouring into it a quantity of Quick ſilver, <lb></lb>we held it ſo, that the ſuperficies of the <lb></lb>Liquor, both in the longer and ſhorter <lb></lb>leg, lay in a Horizontal Line, denoted in <lb></lb>the Scheme by the prick'd Line EF; then <lb></lb>pouring Water into the longer Leg of the <lb></lb><emph type="italics"></emph>Siphon,<emph.end type="italics"></emph.end> till that was almoſt fill'd, we ob<lb></lb>ſerv'd the ſurface of the Quick-ſilver in <lb></lb>that leg to be, by the weight of the Wa<lb></lb>ter, depreſſ'd, as from E to B; and in <lb></lb>the ſhorter leg, to be as much impell'd <lb></lb>upward as from F to G: Whereupon ha<lb></lb>ving formerly ſtuck marks, as well at the <lb></lb>point B, as at the oppoſite point D, we <lb></lb>mealur d both the diſtance DC to have <lb></lb>the height of the Cylinder of Quick-ſil<lb></lb>ver, which was raiſ'd above the Point D <lb></lb>(level with the ſurface of the Quick-ſilver <lb></lb>in the other leg) by the weight of the Wa<lb></lb>ter, and the diſtance BA which gave us <lb></lb>the height of the Cylinder of Water. </s> <s>So <lb></lb>that the diſtance DC amounting to (2 12/54) <lb></lb>Inches, and the height of the Water a<lb></lb>mounting (30 45/50) Inches; and the whole <pb xlink:href="013/01/325.jpg" pagenum="295"></pb>numbers on both ſides, which the annex<lb></lb>ed Fractions being reduc'd to improper <lb></lb>Fractions of the ſame denomination, the <lb></lb>proportion appear'd to be (the denomi<lb></lb>nators beng left out as equal on both ſides) <lb></lb>as 121 to 1665; or by reduction, as one <lb></lb>to (13 92/121). </s></p><p type="main"> <s>Beſides this unuſual way of determi<lb></lb>ning the gravity of ſome things, we mea<lb></lb>ſur'd the proportion betwixt Quick-ſilver <lb></lb>and Water, by the help of ſo exact a bal<lb></lb>lance, as looſes its <emph type="italics"></emph>Æquilibrium<emph.end type="italics"></emph.end> by the <lb></lb>hundredth part of a Grain. </s> <s>But becauſe <lb></lb>there is wont to be committed an over<lb></lb>ſight in weighing Quick-ſilver and Wa<lb></lb>ter, eſpecially if the Orifice of the Veſſel <lb></lb>wherein they are put be any thing wide, in <lb></lb>regard that men heed not that the ſurface <lb></lb>of Water in Veſſels will be concave, <lb></lb>but that of Quick-ſilver, notably convex <lb></lb>or protuberant: To avoid this uſual over<lb></lb>ſight (I ſay) we made uſe of a glaſs bubble, <lb></lb>blown very thin at the Flame of a Lamp, <lb></lb>that it might not be too heavy for the <lb></lb>Ballance, and terminating in a very ſlender <lb></lb>neck, wherein the concavity or convexity <lb></lb>of a Liquor could not be conſiderable: <lb></lb>This Glaſs weighing 23 1/2 Grains, we fill'd <pb xlink:href="013/01/326.jpg" pagenum="296"></pb>almoſt with Quick-ſilver, and faſtning a <lb></lb>mark over againſt the middle of the pro<lb></lb>tuberant Superficies as near as our Eyes <lb></lb>could judge, we found that the Quick<lb></lb>ſilver alone weighed 299 1/32 Grains: Then <lb></lb>the Quick-ſilver being pour'd out, and <lb></lb>the ſame Glaſs being fill'd as full of com<lb></lb>mon Water, we found the Liquor to <lb></lb>weigh 21 7/8 Grains. </s> <s>Whereby it appear'd <lb></lb>that the weight of Water to Quick<lb></lb>ſilver, is as one to (13 19/28): Though our Il<lb></lb>luſtrious <emph type="italics"></emph>Verulam<emph.end type="italics"></emph.end> (queſtionleſs not for <lb></lb>want of Judgement or Care, but of ex<lb></lb>act Inſtruments) makes the proportion <lb></lb>betwixt thoſe two Liquors to be greater <lb></lb>then of 1 to 17. And to adde, that up<lb></lb>on the by, ſince Quick-ſilver and well <lb></lb>rectified Spirit of Wine, are (how juſtly <lb></lb>I ſay not) accounted, the one the hea<lb></lb>vieſt, and the other the lighteſt of Li<lb></lb>quors; we thought to fill in the ſame <lb></lb>Glaſs, and with the ſame Scales to ob<lb></lb>ſerve the difference betwixt them, which <lb></lb>we found to be as of 1 to (16 641/1084); where<lb></lb>by it appear'd, That the difference be<lb></lb>twixt Spirit of Wine, that may be made <lb></lb>to burn all away, (ſuch as was ours) and <lb></lb>common Water, is as betwixt 1 and (1 44/171) </s></p><pb xlink:href="013/01/327.jpg" pagenum="297"></pb><p type="main"> <s>We might here take occaſion to ad<lb></lb>mire, that though Water (as appear'd by <lb></lb>the Experiment formerly mention'd of <lb></lb>the Pewter Veſſel) ſeems not capable of <lb></lb>any conſiderable condenſation, and ſeems <lb></lb>not to have interſperſ'd in it any ſtore of <lb></lb>Air; yet Quick-ſilver, of no greater bulk <lb></lb>then Water, ſhould weigh near fourteen <lb></lb>times as much. </s> <s>But having onely point<lb></lb>ed at this as a thing worthy of conſidera<lb></lb>tion, we will proceed in our inquiry after <lb></lb>the heigth of the Atmoſphere: And to <lb></lb>avoid the trouble of Fractions, we will <lb></lb>aſſume that Quick-ſilver is fourteen times <lb></lb>as heavy as Water, ſince it wants ſo little <lb></lb>of being ſo. </s></p><p type="main"> <s>Wherefore having now given us the <lb></lb>proportion of Air to Water, and Water <lb></lb>to Quick-ſilver, it will be very eaſie to <lb></lb>finde the proportion betwixt Air and <lb></lb>Quick-ſilver, in caſe we will ſuppoſe the <lb></lb>Atmoſphere to be uniformly of ſuch a <lb></lb>conſiſtence as the Air we weighed here <lb></lb>below. </s> <s>For ſince our Engine hath ſuffi<lb></lb><arrow.to.target n="marg46"></arrow.to.target><lb></lb>ciently manifeſted that 'tis the <emph type="italics"></emph>Æquili<lb></lb>brium<emph.end type="italics"></emph.end> with the external Air, that in the <lb></lb><emph type="italics"></emph>Torricellian<emph.end type="italics"></emph.end> Experiment keeps the Quick<lb></lb>ſilver from ſubſiding; And ſince, by our <lb></lb>accurate Experiment formerly mention'd, <pb xlink:href="013/01/328.jpg" pagenum="298"></pb>it appears that a Cylinder of Mercury, <lb></lb>able to ballance a Cylinder of the whole <lb></lb>Atmoſphere, amounted to near about <lb></lb>thirty Inches; and ſince, conſequently <lb></lb>we may aſſume the proportion of Quick<lb></lb>ſilver to Air to be as fourteen thouſand to <lb></lb>one; it will follow, that a Cylinder of <lb></lb>Air, capable to maintain an <emph type="italics"></emph>Æquilibrium,<emph.end type="italics"></emph.end><lb></lb>with a Mercurial Cylinder of two Foot <lb></lb>and an half in height, muſt amount to <lb></lb>35000 Feet of our Engliſh Meaſure; <lb></lb>and conſequently (reckoning five Foot <lb></lb>to a Geometrical Pace, and one thouſand <lb></lb>ſuch Paces to a Mile) to ſeven full <lb></lb>Miles. </s></p><p type="margin"> <s><margin.target id="marg46"></margin.target><gap></gap></s></p><p type="main"> <s>But this (as we lately intimated) pro<lb></lb>ceeds upon the ſuppoſition, that the Air <lb></lb>is every where of the ſame conſiſtence <lb></lb>that we found it near the ſurface of the <lb></lb>Earth; but that cannot with any ſafety <lb></lb>be concluded, not onely for the reaſon I <lb></lb>finde to have been taken notice of by the <lb></lb>Antients, and thus expreſt in <emph type="italics"></emph>Seneca: <lb></lb>Omnis Aër<emph.end type="italics"></emph.end> (ſays he) <emph type="italics"></emph>quo propior eſt terris<emph.end type="italics"></emph.end><lb></lb><arrow.to.target n="marg47"></arrow.to.target><lb></lb><emph type="italics"></emph>hoc craſsior; quemadmodum in aqua & in <lb></lb>omni humore fæx ima eſt, it a in Aëre ſpiſ<lb></lb>ſißima quæ〈qué〉 deſidunt;<emph.end type="italics"></emph.end> but much more, <lb></lb>becauſe the ſpringy Texture of the Aërial <lb></lb>Corpuſcles, makes them capable of a <pb xlink:href="013/01/329.jpg" pagenum="299"></pb>very great compreſſion, which the weight <lb></lb>of the incumbent part of the Atmo<lb></lb>ſphere is very ſufficient to give thoſe that <lb></lb>be undermoſt and near the ſurface of the <lb></lb>Earth. </s> <s>And if we recall to minde thoſe <lb></lb>former Experiments, whereby we have <lb></lb>manifeſted, That Air, much rarefied with<lb></lb>out heat, may eaſily admit a further ra<lb></lb>refaction from heat; and that the Air, even <lb></lb>without being expanded by heat, is capa<lb></lb>ble of being rarefied to above one hundred <lb></lb>and fifty times the extent it uſually poſ<lb></lb>ſeſſes here below; How can it be demon<lb></lb>ſtrated that the Atmoſphere may not, for <lb></lb>ought we know, or at leaſt for ought can <lb></lb>be determin'd by our Statical and Mecha<lb></lb>nical Experiments, riſe to the height of <lb></lb>Five and twenty <emph type="italics"></emph>German<emph.end type="italics"></emph.end> Leagues, if not <lb></lb>of ſome hundred of common Miles? </s></p><p type="margin"> <s><margin.target id="marg47"></margin.target><gap></gap> 4. <lb></lb><gap></gap> 10.</s></p><p type="main"> <s>And this conjecture it ſelf may appear <lb></lb>very injurious to the height whereunto <lb></lb>Exhalations may aſcend, if we will allow <lb></lb><arrow.to.target n="marg48"></arrow.to.target><lb></lb>that there was no miſtake in that ſtrange <lb></lb>Obſervation made at <emph type="italics"></emph>Tolous<emph.end type="italics"></emph.end> in a clear <lb></lb>Night in <emph type="italics"></emph>Auguſt,<emph.end type="italics"></emph.end> by the diligent Ma<lb></lb>thematician <emph type="italics"></emph>Emanuel Magnan,<emph.end type="italics"></emph.end> and thus <lb></lb>Recorded by <emph type="italics"></emph>Ricciolus,<emph.end type="italics"></emph.end> (for I have not at <lb></lb>hand the Authors own Book) <emph type="italics"></emph>Vidit<emph.end type="italics"></emph.end> (ſays <lb></lb>he) <emph type="italics"></emph>ab hor a undecima poſt meridiem uſ〈qué〉 ad<emph.end type="italics"></emph.end><pb xlink:href="013/01/330.jpg" pagenum="300"></pb><emph type="italics"></emph>mediam noctem Lunâ infra horizontem <lb></lb>poſitâ, nubeculam quandam lucidam prope <lb></lb>Meridianum fere uſque ad Zenith diffuſam <lb></lb>quæ conſider at is omnibus non poter at niſi à <lb></lb>ſole illuminari; ideoque altior eſſe debuit <lb></lb>tota umbr a terræ. </s> <s>Addit<emph.end type="italics"></emph.end> (continues <emph type="italics"></emph>Ricci<lb></lb>olus) ſimile quid eveniſſe Michaeli Angelo <lb></lb>Riccio apud Sabinos verſanti nempe viro <lb></lb>in Matheſi eruditiſsimo.<emph.end type="italics"></emph.end></s></p><p type="margin"> <s><margin.target id="marg48"></margin.target><gap></gap></s></p><p type="main"> <s>Various Obſervations made at the <lb></lb>feet, tops, and interjacent parts of high <lb></lb>Mountains, might perchance ſomewhat <lb></lb>aſſiſt us to make an eſtimate in what pro<lb></lb>portion, if in any certain one, the higher <lb></lb>Air is thicker then the lower, and gheſs <lb></lb>at the diſ-form conſiſtence, as to laxity <lb></lb>and compactneſs of the Air at ſeveral <lb></lb>diſtances from us. </s> <s>And if the difficul<lb></lb>ties about the refractions of the Celeſtial <lb></lb>Lights, were ſatisfactorily determin'd, <lb></lb>that might alſo much conduce to the pla<lb></lb>cing due limits to the Atmoſphere (whoſe <lb></lb>Dimenſions thoſe Obſervations about <lb></lb>Refractions ſeem hitherto much to con<lb></lb>tract.) But for the preſent we dare not <lb></lb>pronounce any thing peremptorily con<lb></lb>cerning the height of it, but leave it to <lb></lb>further inquiry: contenting our ſelves to <lb></lb>have manifeſted the miſtake of divers <pb xlink:href="013/01/331.jpg" pagenum="301"></pb>eminent Modern Writers, who will not <lb></lb>allow the Atmoſphere to exceed above <lb></lb>two or three Miles in height (as the Fa<lb></lb>mous K<emph type="italics"></emph>epler<emph.end type="italics"></emph.end> will not the <emph type="italics"></emph>Aër refractivus<emph.end type="italics"></emph.end>) <lb></lb>and to have rendred a reaſon why in the <lb></lb>mention we made in the Notes upon the <lb></lb>firſt Experiment, touching the height of <lb></lb>the Atmoſphere, we ſcrupled not to ſpeak <lb></lb>of it, as if it might be many Miles high. </s></p><p type="main"> <s>WE will now proceed to recite a <lb></lb><arrow.to.target n="marg49"></arrow.to.target><lb></lb><emph type="italics"></emph>Phænomenon,<emph.end type="italics"></emph.end> which, though <lb></lb>made amongſt the firſt, we thought fit <lb></lb>not to mention till after many others, that <lb></lb>we might have the opportunity to ob<lb></lb>ſerve as many Circumſtances of it as we <lb></lb>could, and ſo preſent Your Lordſhip at <lb></lb>once, moſt of what we at ſeveral times <lb></lb>have taken notice of concerning ſo odde <lb></lb>a <emph type="italics"></emph>Phænomenon.<emph.end type="italics"></emph.end></s></p><p type="margin"> <s><margin.target id="marg49"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 37.</s></p><p type="main"> <s>Our Engine had not been long finiſh'd, <lb></lb>when, at the firſt leaſure we could ſteal <lb></lb>from our occaſions to make tryal of it, <lb></lb>we cauſ'd the Air to be pump'd out of <lb></lb>the Receiver; and whil'ſt I was buſied in <lb></lb>entertaining a Learned Friend that juſt <lb></lb>then came to viſit me, an Ingenious By-<pb xlink:href="013/01/332.jpg" pagenum="302"></pb>ſtander, thought he perceiv'd ſome new <lb></lb>kind of Light in the Receiver, of which <lb></lb>giving me haſtily notice, my Friend and <lb></lb>I preſently obſerv'd, that when the Suc<lb></lb>ker was drawn down, immediately upon <lb></lb>the turning of the Key, there appear'd <lb></lb>a kinde of Light in the Receiver, almoſt <lb></lb>like a faint flaſh of Lightening in the <lb></lb>Day-time, and almoſt as ſuddenly did it <lb></lb>appear and vaniſh. </s> <s>Having, not with<lb></lb>out ſome amazement, obſerv'd divers <lb></lb>of theſe Apparitions of Light, we took <lb></lb>notice that the Day was clear, the hour <lb></lb>about ten in the Morning, that the onely <lb></lb>Window in the Room fac'd the North; <lb></lb>and alſo, that by interpoſing a Cloak, or <lb></lb>any opacous Body between the Receiver <lb></lb>and the Window, though the reſt of the <lb></lb>Room were ſufficiently enlightned, yet <lb></lb>the flaſhes did not appear as before, un<lb></lb>leſs the opacous Body were remov'd. <lb></lb></s> <s>But not being able on all theſe Circum<lb></lb>ſtances to ground any firm Conjecture <lb></lb>at the cauſe of this ſurpriſing <emph type="italics"></emph>Phænome<lb></lb>non,<emph.end type="italics"></emph.end> as ſoon as Night was come, we <lb></lb>made the Room very dark; and plying <lb></lb>the Pump, as in the Morning, we could <lb></lb>not, though we often try'd, find, upon <lb></lb>the turning of the Key, ſo much as the <pb xlink:href="013/01/333.jpg" pagenum="303"></pb>leaſt glimmering of Light; whence we <lb></lb>inferr'd, that the flaſh appearing in the <lb></lb>Receiver, did not proceed from any new <lb></lb>Light generated there, but from ſome <lb></lb>reflections of the light of the Sun, or <lb></lb>other Luminous Bodies plac'd without <lb></lb>it; though whence that Reflection <lb></lb>ſhould proceed, it poſ'd us to conje<lb></lb>cture. </s></p><p type="main"> <s>Wherefore the next Morning, ho<lb></lb>ping to inform our ſelves better, we <lb></lb>went about to repeat the Experiment, <lb></lb>but though we could as well as former<lb></lb>ly exhauſt the Receiver, though the <lb></lb>place wherein we made the tryal was the <lb></lb>very ſame; and though other Circum<lb></lb>ſtances were reſembling, yet we could <lb></lb>not diſcover the leaſt appearance of <lb></lb>Light all that Day, nor on divers o<lb></lb>thers on which tryal was again fruitleſ<lb></lb>ly made; nor can we to this very time <lb></lb>be ſure a Day before hand that theſe <lb></lb>Flaſhes will be to be ſeen in our great <lb></lb>Receiver. </s> <s>Nay, having once found the <lb></lb>Engine in a good humour (if I may <lb></lb>ſo ſpeak) to ſhew this trick, and ſent <lb></lb>notice of it to our Learned Friend <lb></lb>Doctor <emph type="italics"></emph>Wallis,<emph.end type="italics"></emph.end> who expreſſ'd a great <pb xlink:href="013/01/334.jpg" pagenum="304"></pb>deſire to ſee this <emph type="italics"></emph>Phænomenon,<emph.end type="italics"></emph.end> though he <lb></lb>were not then above a Bow-ſhoot off, and <lb></lb>made haſte to ſatisfie his Curioſity; yet <lb></lb>by that time he was come, the thing he <lb></lb>came for was no longer to be ſeen; ſo <lb></lb>that having vainly endeavored to exhibit <lb></lb>again the <emph type="italics"></emph>Phænomenon<emph.end type="italics"></emph.end> in his preſence, I <lb></lb>began to apprehend what he might think <lb></lb>of me, when unexpectedly the Engine <lb></lb>preſented us a flaſh, and after that a ſecond, <lb></lb>and as many more, as ſuffic'd to ſatisfie <lb></lb>him that we might very well confidently <lb></lb>relate, that we have our ſelves ſeen this <lb></lb><emph type="italics"></emph>Phænomenon,<emph.end type="italics"></emph.end> though not confidently pro<lb></lb>miſe to ſhew it others. </s></p><p type="main"> <s>And this unſucceſsfulneſs whereto our <lb></lb>Experiment is lyable, being ſuch, that by <lb></lb>all our watchfulneſs and tryals, we could <lb></lb>never reduce it to any certain Rules or <lb></lb>Obſervations; ſince in all conſtitutions <lb></lb>of the Weather, times of the Day, <emph type="italics"></emph>&c.<emph.end type="italics"></emph.end><lb></lb>it will ſometimes anſwer, and ſometimes <lb></lb>diſ-appoint our Expectations; We are <lb></lb>much diſcourag'd from venturing to frame <lb></lb>an <emph type="italics"></emph>Hypotheſis<emph.end type="italics"></emph.end> to give an account of it: <lb></lb>which if the Experiment did conſtantly <lb></lb>ſucceed, might the more hopefully be at<lb></lb>tempted; by the help of the following <lb></lb><emph type="italics"></emph>Phænomena<emph.end type="italics"></emph.end> laid together: ſome of them <pb xlink:href="013/01/335.jpg" pagenum="305"></pb>produc'd upon tryals purpoſely made <lb></lb>to examine the validity of the conjectures, <lb></lb>other tryals had ſuggeſted. </s></p><p type="main"> <s>Firſt then we obſerv'd, that the Appa<lb></lb>rition of Light may be made as well by <lb></lb>Candle-light, as by Day-light; and in <lb></lb>whatever poſition the Candle be held, in <lb></lb>reference to the Receiver, as on this or <lb></lb>that hand of it, above it, beneath it, or <lb></lb>any other way, provided the Beams of <lb></lb>Light be not hinder'd from falling upon <lb></lb>the Veſſel. </s></p><p type="main"> <s>Next, we noted that the flaſh appears <lb></lb>immediately upon the turning of the <lb></lb>Key, to let the Air out of the Receiver <lb></lb>into the empty'd Cylinder, in ſo much <lb></lb>that I remember not that when at any <lb></lb>time in our great Receiver, the Stop-cock <lb></lb>was open'd before the Cylinder was ex<lb></lb>hauſted (whereby it came to paſs that the <lb></lb>Air did rather deſcend, then ruſh into the <lb></lb>Cylinder) the often mention'd flaſh ap<lb></lb>pear'd to our eyes. </s></p><p type="main"> <s>Yet, we further obſerv'd, that when in<lb></lb>ſtead of the great Receiver we made uſe <lb></lb>of a ſmall Glaſs, not containing above a <lb></lb>pound and a half of Water, the <emph type="italics"></emph>Phæno<lb></lb>menon<emph.end type="italics"></emph.end> might be exhibited though the <lb></lb>Stop-cock were open, provided the <pb xlink:href="013/01/336.jpg" pagenum="306"></pb>Sucker were drawn nimbly down. </s></p><p type="main"> <s>We noted too, that when we began to <lb></lb>empty the Receiver, the appearances of <lb></lb>Light were much more conſpicuous <lb></lb>then towards the latter end, when little <lb></lb>Air at a time could paſs out of the Re<lb></lb>ceiver. </s></p><p type="main"> <s>We obſerv'd alſo, that when the Suc<lb></lb>ker had not been long before well Oyl'd, <lb></lb>and inſtead of the great Receiver, the <lb></lb>ſmaller Veſſel above-mention'd was em<lb></lb>ploy'd; We obſerv'd, I ſay, that then, <lb></lb>upon the opening of the Stop-cock, as <lb></lb>the Air deſcended out of the Glaſs in<lb></lb>to the empty'd Cylinder, ſo at the ſame <lb></lb>time there aſcended out of the Cylinder <lb></lb>into the Veſſel a certain Steam, which <lb></lb>ſeem'd to conſiſt of very little Bubbles, <lb></lb>or other minute Corpuſcles thrown up <lb></lb>from the Oyl, rarefied by the attrition it <lb></lb>ſuffered in the Cylinder. </s> <s>For at the <lb></lb>ſame time that theſe Steams aſcended <lb></lb>into the Glaſs, ſome of the ſame kinde <lb></lb>manifeſtly iſſued out like a little Pillar of <lb></lb>Smoke at the Orifice of the Valve, when <lb></lb>that was occaſionally open'd. </s> <s>And theſe <lb></lb>Steams frequently enough preſenting <lb></lb>themſelves to our view, we found, by <lb></lb>expoſing the Glaſs to a clear Light, that <pb xlink:href="013/01/337.jpg" pagenum="307"></pb>they were wont to play up and down <lb></lb>in it, and ſo by their whiteiſhneſs, to e<lb></lb>mulate in ſome meaſure the apparition of <lb></lb>Light. </s></p><p type="main"> <s>For we likewiſe ſometimes found, by <lb></lb>watchful obſervation, that when the <lb></lb>Flaſh was great, not onely at the very <lb></lb>inſtant the Receiver loſt of its tranſpa<lb></lb>rency, by appearing full of ſome kinde <lb></lb>of whitiſh ſubſtance; but that for ſome <lb></lb>ſhort time after the ſides of the Glaſs <lb></lb>continued ſomewhat opacous, and <lb></lb>ſeem'd to be darken'd, as if ſome <lb></lb>whitiſh Steam adher'd to the inſide of <lb></lb>them. </s></p><p type="main"> <s>He that would render a Reaſon of <lb></lb>the <emph type="italics"></emph>Phænomenon,<emph.end type="italics"></emph.end> whereof all theſe are <lb></lb>not all the Circumſtances, muſt doe <lb></lb>two things; whereof the one is diffi<lb></lb>cult, and the other little leſs then im<lb></lb>poſſible: For he muſt give an Ac<lb></lb>count not onely whence the appearing <lb></lb>whiteneſs proceeds, but wherefore that <lb></lb>whiteneſs does ſometimes appear and <lb></lb>ſometimes not. </s></p><p type="main"> <s>For our part, we freely confeſſe <lb></lb>our ſelves at a loſſe about rendering <pb xlink:href="013/01/338.jpg" pagenum="308"></pb>a Reaſon of the leſs difficult part of the <lb></lb>Problem: And though Your Lord<lb></lb>ſhip ſhould ev'n preſs us to declare what <lb></lb>Conjecture it was, that the above-recited <lb></lb>Circumſtances ſuggeſted to us, we ſhould <lb></lb>propoſe the thoughts we then had, no o<lb></lb>therwiſe then as bare Conjectures. </s></p><p type="main"> <s>In caſe then our <emph type="italics"></emph>Phænomenon<emph.end type="italics"></emph.end> had con<lb></lb>ſtantly and uniformly appear'd, we ſhould <lb></lb>have ſuſpected it to have been produc'd <lb></lb>after ſome ſuch manner as follows. </s></p><p type="main"> <s>Firſt, we obſerv'd that, though that <lb></lb>which we ſaw in our Receiver ſeem'd to <lb></lb>be ſome kinde of Light, yet it was indeed <lb></lb>but a whiteneſs which did (as hath alrea<lb></lb>dy been noted) opacate (as ſome ſpeak) <lb></lb>the inſide of the Glaſs. </s></p><p type="main"> <s>Next we conſider'd, that our com<lb></lb>mon Air abounds with Particles or little <lb></lb>Bodies, capable to reflect the Beams of <lb></lb>Light. </s> <s>Of this we might eaſily give di<lb></lb>vers proofs, but we ſhall name but two: <lb></lb>The one, that vulgar obſervation of the <lb></lb>Motes that appear in Multitudes ſwim<lb></lb>ming up and down in the Air, when the <lb></lb>Sun-beams ſhooting into a Room, or any <lb></lb>other ſhady Place diſcover them, though <lb></lb>otherwiſe the eye cannot diſtinguiſh them <pb xlink:href="013/01/339.jpg" pagenum="309"></pb>from the reſt of the Air: The other proof <lb></lb>we will take from what we (and no doubt <lb></lb>very many others) have obſerv'd, touch<lb></lb>ing the Illumination of the Air in the <lb></lb>Night. </s> <s>And we particularly remember, <lb></lb>that, being at ſome diſtance from <emph type="italics"></emph>London<emph.end type="italics"></emph.end><lb></lb>one Night, that the People, upon a very <lb></lb>well-come Occaſion, teſtified their Joy <lb></lb>by numerous Bon-fires; though, by rea<lb></lb>ſon of the Interpoſition of the Houſes, <lb></lb>we could not ſee the Fires themſelves, yet <lb></lb>we could plainly ſee the Air all enlighten'd <lb></lb>over and near the City; which argu'd, <lb></lb>that the lucid Beams ſhot upwards from <lb></lb>the Fires, met in the Air with Corpuſcles <lb></lb>opacous enough to reflect them to our <lb></lb>Eyes. </s></p><p type="main"> <s>A third thing that we conſidered, was, <lb></lb>That white may be produc'd (without <lb></lb>excluding other ways, or denying inviſi<lb></lb>ble Pores in the ſolideſt Bodies) when <lb></lb>the continuity of a Diaphanous Body <lb></lb>happens to be interrupted by a great num<lb></lb>ber of Surfaces, which, like ſo many <lb></lb>little Looking-glaſſes, do confuſedly re<lb></lb>preſent a multitude of little and ſeeming<lb></lb>ly contiguous Images of the elucid Body. <lb></lb></s> <s>We ſhall not inſiſt on the explanation of <lb></lb>this, but refer You for it to what we have <pb xlink:href="013/01/340.jpg" pagenum="310"></pb>ſaid in another Paper (touching Co<lb></lb>lours.) But the Inſtances that ſeem to <lb></lb>prove it are obvious: For Water or whites <lb></lb>of Eggs beaten to froth, do loſe their <lb></lb>tranſparency and appear white. </s> <s>And ha<lb></lb>ving out of one of our leſſer Receivers <lb></lb>carefully drawn out the Air, and ſo order'd <lb></lb>it, that the hole by which the Water was <lb></lb>to get in, was exceeding ſmall, that the <lb></lb>Liquor might be the more broken in its <lb></lb>paſſage thorow it, we obſerv'd with plea<lb></lb>ſure, That, the Neck being held under <lb></lb>Water, and the little hole newly men<lb></lb>tion'd being open'd, the Water that ruſh'd <lb></lb>in was ſo broken, and acquired ſuch a mul<lb></lb>titude of new Surfaces, that the Receiver <lb></lb>ſeem'd to be full rather of Milk then Wa<lb></lb>ter. </s> <s>We have likewiſe found out, That <lb></lb>by heating a lump of Cryſtal to a certain <lb></lb>degree, and quenching it in fair Water, it <lb></lb>would be diſcontinu'd by ſuch a multi<lb></lb>tude of Cracks, (which created new Sur<lb></lb>faces within it) that though it would not <lb></lb>fall aſunder, but retain its former ſhape, <lb></lb>yet it would loſe its tranſparency, and ap<lb></lb>pear white. </s></p><p type="main"> <s>Upon theſe Conſiderations, My Lord, <lb></lb>and ſome others, it ſeem'd not abſur'd to <lb></lb>imagine, That upon the ruſhing of the Air <pb xlink:href="013/01/341.jpg" pagenum="311"></pb>out of the Receiver into the empty'd Cy<lb></lb>linder, the Air in the Receiver being ſud<lb></lb>denly and vehemently expanded, the Tex<lb></lb>ture of it was as ſuddenly alter'd, and the <lb></lb>parts made ſo to ſhift places (and perhaps <lb></lb>ſome of them to change poſtures) as du<lb></lb>ring their new and vehement Motion and <lb></lb>their varied Scituation, to diſturb the <lb></lb>wonted continuity and ſo the Diapha<lb></lb>neity of the Air; which (as we have alrea<lb></lb>dy noted) upon its ceaſing to be a tran<lb></lb>ſparent Body, without the interpoſition <lb></lb>of colour'd things, muſt eaſily degene<lb></lb>rate into white. </s></p><p type="main"> <s>Several things there were that made <lb></lb>this Conjecture ſeem the leſs improba<lb></lb>ble. </s> <s>As firſt, That the whiteneſs al<lb></lb>ways appear'd greater when the Exſucti<lb></lb>on began to be made, whil'ſt there was <lb></lb>ſtore of Air in the Receiver, then when <lb></lb>the Air was in great part drawn out. </s> <s>And <lb></lb>next, That, having exhauſted the Re<lb></lb>ceiver, and apply'd to the hole in the <lb></lb>Stop-cock a large bubble of clear Glaſs, in <lb></lb>ſuch a manner, that we could at pleaſure let <lb></lb>the Air paſs out at the ſmall Glaſs into the <lb></lb>great one, and eaſily fill the ſmall one with <lb></lb>Air again, We obſerv'd with pleaſure, <pb xlink:href="013/01/342.jpg" pagenum="312"></pb>That upon the opening the paſſage be<lb></lb>twixt the two Glaſſes, the Air in the <lb></lb>ſmaller having ſo much room in the great<lb></lb>er to receive it, the Diſſilition of that <lb></lb>Air was ſo great, that the ſmall Viol <lb></lb>ſeem'd to be full of Milk; and this Expe<lb></lb>riment we repeated ſeveral times. </s> <s>To <lb></lb>which we may adde, That, having pro<lb></lb>vided a ſmall Receiver, whoſe upper Ori<lb></lb>fice was ſo narrow that I could ſtop it with <lb></lb>my Thumb, I obſerv'd, that when upon <lb></lb>the Exſuction of the Air the capacity of <lb></lb>the Glaſs appear'd white, if by a ſudden <lb></lb>removal of my Thumb I let in the out<lb></lb>ward Air, that whiteneſs would imme<lb></lb>diately vaniſh. </s> <s>And whereas it may be <lb></lb>objected, That in the Inſtance formerly <lb></lb>mention'd, Water turning from perſpi<lb></lb>cuous to white, there intervenes the Air, <lb></lb>which is a Body of a Heterogeneous na<lb></lb>ture, and muſt turn it into Bubbles to <lb></lb>make it loſe its tranſparency. </s> <s>We may <lb></lb>borrow an Anſwer from an Experiment <lb></lb>we deliver in another Treatiſe, where we <lb></lb>teach how to make two very volatile Li<lb></lb>quors, which being gently put together <lb></lb>are clear as Rock-water, and yet will al<lb></lb>moſt in a moment, without the ſub-ingreſ<lb></lb>ſion of Air to turn them into Bubbles, ſo <pb xlink:href="013/01/343.jpg" pagenum="313"></pb>alter the diſpoſition of their inſenſible <lb></lb>parts, as to become a white and conſiſtent <lb></lb>Body. </s> <s>And this happens not as in the <lb></lb>precipitation of <emph type="italics"></emph>Benjamin,<emph.end type="italics"></emph.end> and ſome o<lb></lb>ther Reſinous Bodies, which being diſ<lb></lb>ſolv'd in Spirit of Wine, may, by the effu<lb></lb>ſion of fair Water, be turn'd into a ſeem<lb></lb>ingly Milky ſubſtance. </s> <s>For this white<lb></lb>neſs belongs not to the whole Liquor, but <lb></lb>to the Corpuſcles of the diſſolv'd Gum, <lb></lb>which after a while ſubſiding leave the Li<lb></lb>quor tranſparent, themſelves onely re<lb></lb>maining white: Whereas in our caſe, 'tis <lb></lb>from the vary'd texture of the whole for<lb></lb>merly tranſparent fluid Body, and not <lb></lb>from this or that part that this whiteneſſe <lb></lb>reſults: For the Body is white thorowout, <lb></lb>and will long continue ſo; and yet may, <lb></lb>in proceſs of time, without any addition, <lb></lb>be totally reduc'd into a tranſparent Bo<lb></lb>dy as before. </s></p><p type="main"> <s>But beſides the Conjecture inſiſted on <lb></lb>all this while, we grounded another upon <lb></lb>the following Obſervation, which was, <lb></lb>That having convey'd ſome ſmoke into <lb></lb>our Receiver plac'd againſt a Window, we <lb></lb>obſerv'd, that upon the exſuction of the <lb></lb>Air, the Corpuſcles that were ſwimming <lb></lb>in it, did manifeſtly enough make the Re-<pb xlink:href="013/01/344.jpg" pagenum="314"></pb>ceiver ſeem more opacous at the very <lb></lb>moment of the ruſhing out of the Air: <lb></lb>For conſidering that the whiteneſs, whoſe <lb></lb>cauſe we enquire of, did but ſometimes ap<lb></lb>pear, it ſeem'd not impoſſible but that at <lb></lb>ſuch times the Air in the Receiver might <lb></lb>abound with Particles, capable of re<lb></lb>flecting the Light in the manner requiſite <lb></lb>to exhibit a white colour, by their being <lb></lb>put into a certain unuſual Motion. </s> <s>As <lb></lb>may be in ſome meaſure illuſtrated by <lb></lb>this, That the new motion of the freſhly <lb></lb>mention'd Fumes, made the inſide of the <lb></lb>Receiver appear ſomewhat darker then <lb></lb>before: And partly by the nature of our <lb></lb>formerly mention'd ſmoking Liquor, <lb></lb>whoſe parts though they ſeem'd tranſpa<lb></lb>rent whil'ſt they compoſ'd a Liquor, yet <lb></lb>when the ſame Corpuſcles, upon the un<lb></lb>ſtopping of the Glaſs, were put into a <lb></lb>new motion, and diſpoſ'd after a new <lb></lb>manner, they did opacate that part of the <lb></lb>Air they mov'd in, and exhibited a great<lb></lb>er whiteneſs then that which ſometimes <lb></lb>appears in our Pneumatical Veſſel. </s> <s>Nor <lb></lb>ſhould we content our ſelves with this ſin<lb></lb>gle Inſtance, to manifeſt, That little Bo<lb></lb>dies, which being rang'd after one manner, <lb></lb>are Diaphanous and Colourleſs, may, by <pb xlink:href="013/01/345.jpg" pagenum="315"></pb>being barely agitated, diſperſ'd, and con<lb></lb>ſequently otherways rang'd, exhibite a <lb></lb>colour, if we were not unwilling to rob <lb></lb>our Collection of Experiments concern<lb></lb>ing Colours. </s></p><p type="main"> <s>But, My Lord, I foreſee You may <lb></lb>make ſome Objections againſt our pro<lb></lb>poſed gheſs, which perhaps I ſhall ſcarce <lb></lb>be able to anſwer, eſpecially, if You in<lb></lb>ſiſt upon having me render a Reaſon why <lb></lb>our <emph type="italics"></emph>Phænomenon<emph.end type="italics"></emph.end> appears not conſtant<lb></lb>ly. </s></p><p type="main"> <s>I might indeed anſwer, that probably <lb></lb>it would do ſo, if inſtead of our great <lb></lb>Receiver we uſe ſuch a ſmall Viol as we <lb></lb>have lat<emph type="italics"></emph>e<emph.end type="italics"></emph.end>ly mention'd, wherein the Diſſi<lb></lb>lition of the Air being much greater, is <lb></lb>like to be the more conſpicuous: Since I <lb></lb>remember not that we ever made our try<lb></lb>al with ſuch ſmall Veſſels, without find<lb></lb>ing the expected whiteneſs to appear. </s> <s>But <lb></lb>it would remain to be explicated, why in <lb></lb>our great Receiver the <emph type="italics"></emph>Phænomenon<emph.end type="italics"></emph.end> ſhould <lb></lb>ſometimes be ſeen, and oftentimes not ap<lb></lb>pear. </s> <s>And though that Conjecture which <lb></lb>we laſt made ſhould not be rejected, yet if <lb></lb>we were further preſſ'd to aſſign a reaſon <lb></lb>why the Air ſhould abound with ſuch Par<lb></lb>ticles, as we there ſuppoſe, more at one <pb xlink:href="013/01/346.jpg" pagenum="316"></pb>time then another, we are not yet pro<lb></lb>vided of any better Anſwer, then this <lb></lb>general one, That the Air about us, <lb></lb>and much more that within the Receiver, <lb></lb>may be much alter'd by ſuch cauſes as few <lb></lb>are aware of: For, not to repeat thoſe <lb></lb>probable Arguments of this Aſſertion <lb></lb>which we have occaſionally mention'd <lb></lb>here and there in the former part of this <lb></lb>Epiſtle, we will here ſet down two or <lb></lb>three Inſtances to verifie the ſame Propo<lb></lb>ſition. </s> <s>Firſt, I finde that the Learned <lb></lb><emph type="italics"></emph>Foſephus Acoſta,<emph.end type="italics"></emph.end> among other Judicious <lb></lb><arrow.to.target n="marg50"></arrow.to.target><lb></lb>Obſervations he made in <emph type="italics"></emph>America,<emph.end type="italics"></emph.end> hath <lb></lb>this concerning the Effects of ſome <lb></lb>Winds; <emph type="italics"></emph>There are<emph.end type="italics"></emph.end> (ſays he) <emph type="italics"></emph>Winds which <lb></lb>naturally trouble the Water of the Sea, and <lb></lb>make it green, and black; others, clear as <lb></lb>Cryſtal.<emph.end type="italics"></emph.end></s><s> Next, we have obſerv'd, That <lb></lb>though we conveyd into the Receiver our <lb></lb>Scales, and the <emph type="italics"></emph>Pendula<emph.end type="italics"></emph.end> formerly men<lb></lb>tion'd, clean and bright; yet after the Re<lb></lb>ceiver had been empty'd, and the Air let in <lb></lb>again, the gloſs or luſtre both of the one, <lb></lb>and of the other, appear'd tarniſh'd by a <lb></lb>beginning ruſt. </s> <s>And in the laſt place, we <lb></lb>will ſubjoyn an Obſervation we made <lb></lb>ſome Years ago, which hath been heard <lb></lb>of by divers Ingenious Men, and ſeen <pb xlink:href="013/01/347.jpg" pagenum="317"></pb>by ſome of them: We had, with pure <lb></lb>Spirit of Wine, drawn a Tincture out of <lb></lb>a certain Concrete which uſes to be rec<lb></lb>koned among Mineral Bodies; And this <lb></lb>Tincture being very pure and tranſparent, <lb></lb>we did, becauſe we put a great value upon <lb></lb>it, put into a Cryſtal Viol which we care<lb></lb>fully ſtopp'd, and lock'd up in a Preſs a<lb></lb>mong ſome other things that we ſpecial<lb></lb>ly priz'd. </s> <s>This Liquor being a Chy<lb></lb>mical Rarity, and beſides, very defecate <lb></lb>and of a pleaſing Golden Colour; we <lb></lb>had often occaſion to look upon it, and <lb></lb>ſo to take notice, that one time it ſeem'd <lb></lb>to be very much troubled, and not clear <lb></lb>as it was wont to be: Whereupon we ima<lb></lb>gined, that though it would be ſomething <lb></lb>ſtrange, yet it was not impoſſible that <lb></lb>ſome Precipitation of the Mineral Cor<lb></lb>puſcles was then happening, and that <lb></lb>thence the Liquor was opacated; but, <lb></lb>finding after ſome days that though the <lb></lb>expected Precipitation had not been <lb></lb>made, yet the Liquor, retaining its for<lb></lb>mer vivid Colour, was grown clear again <lb></lb>as before; we ſomewhat wondered at it, <lb></lb>and locking it up again in the ſame Preſs, <lb></lb>we reſolved to obſerve, both whether <lb></lb>the like changes would again appear in <pb xlink:href="013/01/348.jpg" pagenum="318"></pb>our Tincture; and whether in caſe they <lb></lb>ſhould appear, they would be aſcribable <lb></lb>to the alterations of the Weather. </s> <s>But <lb></lb>though, during the greateſt part of a Win<lb></lb>ter and a Spring, we took pleaſure to ob<lb></lb>ſerve, how the Liquor would often grow <lb></lb>turbid, and after a while clear again: Yet <lb></lb>we could not finde that theſe Mutations <lb></lb>depended upon any that were manifeſt in <lb></lb>the Air, whieh would be often dark and <lb></lb>clouded, when the Tincture was clear and <lb></lb>tranſparent; as on the other ſide, in clear <lb></lb>Weather the Liquor would appear ſome<lb></lb>times troubled, and more opacous. </s> <s>So <lb></lb>that being unable to give an account of <lb></lb>theſe odde changes in our Tincture (which <lb></lb>we ſuppoſe we have not yet loſt, though <lb></lb>we know not whether it have loſt its fickle <lb></lb>Nature) either by thoſe of the Air, or <lb></lb>any thing elſe that occurr'd to our <lb></lb>thoughts; we could not but ſuſpect that <lb></lb>there may be in divers Bodies, as it were <lb></lb>Spontaneous Mutations, that is, ſuch <lb></lb>changes as depend not upon manifeſt <lb></lb>Cauſes. </s> <s>But, My Lord, what has been <lb></lb>all this while ſaid concerning our <emph type="italics"></emph>Phæno<lb></lb>menon,<emph.end type="italics"></emph.end> is offer'd to You, not as contain<lb></lb>ing a ſatisfactory Account of it, but to <lb></lb>aſſiſt You to give Yourſelf one. </s></p><pb xlink:href="013/01/349.jpg" pagenum="319"></pb><p type="margin"> <s><margin.target id="marg50"></margin.target><gap></gap></s></p><p type="main"> <s>WE took a Glaſs Veſſel, open <lb></lb><arrow.to.target n="marg51"></arrow.to.target><lb></lb>at the top, and into it we put <lb></lb>a mixture of Snow and common Salt <lb></lb>(ſuch a mixture as we have in another <lb></lb>Treatiſe largely diſcourſed of) and in<lb></lb>to the midſt of this mixture we ſet a <lb></lb>Glaſſe, of a Cylindrical form, cloſely <lb></lb>ſtopp'd at the lower end with Plaiſter, <lb></lb>and open at the upper, at which we <lb></lb>fill'd it with common Water. </s> <s>Theſe <lb></lb>things being let down into the Recei<lb></lb>ver, and the Pump being ſet awork, <lb></lb>the Snow began to melt ſomewhat fa<lb></lb>ſter then we expected; whether upon <lb></lb>the account of the Exſuction of the <lb></lb>Air, or becauſe there was but little of <lb></lb>the Snow, or whether for any other <lb></lb>Reaſon, it appeared doubtfull. </s> <s>But <lb></lb>however, by that time the Receiver <lb></lb>had been conſiderably exhauſted, which <lb></lb>was done in leſſe then 1/4 of an hour, <lb></lb>we perceived the Water near the bot<lb></lb>tom of the Glaſs Cylinder to Freeze, <lb></lb>and the Ice by a little longer ſtay, ſeem'd <lb></lb>to encreaſe, and to riſe ſomewhat higher <pb xlink:href="013/01/350.jpg" pagenum="320"></pb>then the ſurface of the ſurrounding Li<lb></lb>quor, where into almoſt all the Snow and <lb></lb>Salt were reſolv'd. </s> <s>The Glaſs being ta<lb></lb>ken out, it appear'd that the Ice was as <lb></lb>thick as the inſide of the Glaſs it fill'd, <lb></lb>though into that I could put my Thumb. <lb></lb></s> <s>The upper ſurface of the Ice was very <lb></lb>concave, which whether it were due to <lb></lb>any unheeded accident, or to the exſu<lb></lb>ction of the Air, we leave to be deter<lb></lb>min'd by further tryal. </s> <s>And laſtly, the <lb></lb>Ice held againſt the Light, appear'd not <lb></lb>deſtitute of Bubbles, though ſome By<lb></lb>ſtanders thought they were fewer then <lb></lb>would have been found if the Water had <lb></lb>been frozen in the open Air. </s> <s>The like <lb></lb>Experiment we try'd alſo another time in <lb></lb>one of our ſmall Receivers, with not un<lb></lb>like ſucceſs. </s></p><p type="margin"> <s><margin.target id="marg51"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 38.</s></p><p type="main"> <s>And on this occaſion, My Lord, give <lb></lb>me leave to propoſe a Problem, which <lb></lb>ſhall be this: Whence proceeds that <lb></lb>ſtrange force that we may ſometimes ob<lb></lb>ſerve in frozen Water, to break the Bo<lb></lb>dies that Impriſon it, though hard and ſo<lb></lb>lid? </s> <s>That there is ſuch a force in Wa<lb></lb>ter expoſ'd to Congelation, may be ga<lb></lb>ther'd not onely from what may be often <lb></lb>obſerv'd in Winter, of the burſting of <pb xlink:href="013/01/351.jpg" pagenum="321"></pb>Glaſſes too cloſe ſtopp'd, fill'd with Wa<lb></lb>ter or aqueous Liquors, but by Inſtances <lb></lb>as much more conſiderable as leſs obvi<lb></lb>ous. </s> <s>For I remember, that an Ingenious <lb></lb>Stone-cutter not long ſince complain'd to <lb></lb>me, That ſometimes, through the negli<lb></lb>gence of Servants, the Rain being ſuffer<lb></lb>ed to ſoak into Marble Stones, the ſuper<lb></lb>vening violent Froſts would burſt the <lb></lb>Stones, to the Profeſſors no ſmall dam<lb></lb>age. </s> <s>And I remember another Trades<lb></lb>man, in whoſe Houſe I had Lodgings, was <lb></lb>laſt Winter complaining, that even Im<lb></lb>plements made of Bell-metal, being care<lb></lb>leſly expoſ'd to the wet, have been broken <lb></lb>and ſpoil'd by the Water, which, having <lb></lb>gotten into the little Cavities and Cran<lb></lb>nies of the Metal, was there afterwards <lb></lb>frozen and expanded into Ice. </s> <s>And to <lb></lb>theſe Relations, we can adde one of the <lb></lb><arrow.to.target n="marg52"></arrow.to.target><lb></lb>formerly mention'd <emph type="italics"></emph>Cabæus's,<emph.end type="italics"></emph.end> whereby <lb></lb>they not onely may be confirm'd, but are <lb></lb>ſurpaſſ'd: For he tells us, That he ſaw a <lb></lb>huge Veſſel of exceeding hard Marble, <lb></lb>ſplit aſunder by congel'd Water, whoſe <lb></lb>Rarefaction, ſays our Author, prov'd ſo <lb></lb>vehement, that the hardneſs of the Stone <lb></lb>yielded to it; and ſo a Veſſel was broken, <lb></lb>which would not have been ſo by 100 <pb xlink:href="013/01/352.jpg" pagenum="322"></pb>Yoke of Oxen drawing it ſeveral ways. </s> <s>I <lb></lb>know, My Lord, that to ſolve this Pro<lb></lb>blem, it will be ſaid, That Congelation <lb></lb>does not (as is commonly, but erroneouſly <lb></lb>preſum'd) reduce water into leſs room <lb></lb>then it poſſeſſ'd before, but rather makes <lb></lb>it take up more. </s> <s>And I have elſewhere <lb></lb>prov'd by particular Experiments, That <lb></lb>whether or no Ice may be truly ſaid to be <lb></lb>Water rarefi'd (for that ſeems queſtion<lb></lb>able) it may be ſaid to take up more room <lb></lb>then the Water did before Glaciation. <lb></lb></s> <s>But though we grant that freezing makes <lb></lb>Water ſwell, yet, how Cold (which in <lb></lb>Weather-Glaſſes manifeſtly condences <lb></lb>the Air) ſhould expand either the Water, <lb></lb>or the intercepted Air ſo forcibly, as to <lb></lb>perform ſuch things as we have newly re<lb></lb>lated, will yet remain a Problem. </s></p><p type="margin"> <s><margin.target id="marg52"></margin.target><emph type="italics"></emph>In <gap></gap>.<emph.end type="italics"></emph.end> 4. <lb></lb><gap></gap></s></p><p type="main"> <s>WE took an Oval Glaſs, clear and <lb></lb><arrow.to.target n="marg53"></arrow.to.target><lb></lb>(leaſt it ſhould break) pretty <lb></lb>ſtrong, with a ſhort Neck at the obtuſer <lb></lb>end, through this Neck, we thruſt almoſt <lb></lb>to the bottom, a Pipe of Glaſs, which was <lb></lb>cloſely Cemented to the newly mention'd <lb></lb>Neck, the upper part of which Pipe, <lb></lb>was drawn in ſome places more ſlender <pb xlink:href="013/01/353.jpg" pagenum="323"></pb>then a Crows Quill, that the changes of <lb></lb>the Air in that. </s> <s>Glaſs Egge might be the <lb></lb>more conſpicuous; Then there was con<lb></lb>vey'd into the Glaſs five or ſix Spoon<lb></lb>fulls of Water, part of which, by blow<lb></lb>ing Air into the Egge, was raiſ'd into the <lb></lb>above-mention'd ſlender part of the Pipe, <lb></lb>ſo that the Water was interpoſ'd between <lb></lb>the external Air, and that included in the <lb></lb>Egge. </s> <s>This Weather-glaſs (delineated <lb></lb>in the fourteenth Figure) was ſo plac'd, <lb></lb>and cloſ'd up in the cavity of one of our <lb></lb>ſmall Receivers, that onely the ſlender <lb></lb>part of the Pipe, to the heigth of four <lb></lb>or five Inches, paſſing thorow a hole in <lb></lb>the Cover, remain'd expoſ'd to the open <lb></lb>Air. </s></p><p type="margin"> <s><margin.target id="marg53"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 39.</s></p><p type="main"> <s>The Pump being ſet a work, upon <lb></lb>the Exſuction of the Air, the Water in <lb></lb>the Pipe deſcended about a quarter of an <lb></lb>Inch, and this upon two or three reitera<lb></lb>ted tryals; which ſeem'd ſufficiently to <lb></lb>argue that there was no heat produc'd in <lb></lb>the Receiver upon the Exſuction of the <lb></lb>Air: For even a little heat would pro<lb></lb>bably have been diſcover'd by that Wea<lb></lb>ther-glaſs, ſince upon the bare applica<lb></lb>tion of my hand to the outſide of the <lb></lb>Receiver, the warmth having after ſome <pb xlink:href="013/01/354.jpg" pagenum="324"></pb>time been communicated or propagated <lb></lb>through both the Glaſſes, and the inter<lb></lb>val betwixt them to the Impriſon'd Air, <lb></lb>did ſo rarifie that, as to inable it, by preſ<lb></lb>ſing upon the ſubjacent Water, to impel <lb></lb>that in the Pipe very many times as far as <lb></lb>it had fallen downwards upon the Exſucti<lb></lb>on of the Air. </s></p><p type="main"> <s>Yet ſhall not we conclude, that in the <lb></lb>cavity of the Receiver the cold was great<lb></lb>er after the Exſuction of the Air then be<lb></lb>fore. </s></p><p type="main"> <s>For if it be demanded what then could <lb></lb>cauſe the fore-mention'd ſubſiding of the <lb></lb>Water? </s> <s>it may be anſwered, That pro<lb></lb>bably it was the reaching of the Glaſs <lb></lb>Egge, which, upon the Exſuction of the <lb></lb>ambient Air, was unable to reſiſt alto<lb></lb>gether as much as formerly the preſſure of <lb></lb>the included Air, and of the Atmoſphere, <lb></lb>which by the intervenſion of the Water, <lb></lb>preſſ'd upon its concave ſurface: Which <lb></lb>ſeem'd probable, as well by what was a<lb></lb>bove deliver'd, in the Experiment about <lb></lb>the breaking of the Glaſs by the force of <lb></lb>the Atmoſphere; as by this notable Cir<lb></lb>cumſtance (which we divers times ob<lb></lb>ſerv'd) That when by drawing the Air out <lb></lb>of the Receiver, the Water in the Pipe <pb xlink:href="013/01/355.jpg" pagenum="325"></pb>was ſubſided, upon the readmiſſion of the <lb></lb>external Air to preſs againſt the convex <lb></lb>ſurface of the Egge, the Water was pre<lb></lb>ſently re-impell'd to its former height: <lb></lb>Which would perhaps appear leſs ſtrange <lb></lb>to Your Lordſhip, if You had yet ſeen <lb></lb>what we have heretofore taught in ano<lb></lb>ther Treatiſe concerning the Spring that <lb></lb>may be diſcover'd in Glaſs, as rigid and <lb></lb>inflexible a Body as it is generally e<lb></lb>ſteem'd. </s> <s>And in the mean while it may <lb></lb>ſerve the turn to cauſe a Glaſs Egge to be <lb></lb>blown exceeding thin, and then, having <lb></lb>broken it, try how far you can by degrees <lb></lb>bend ſome narrow parts of it; and how <lb></lb>readily, upon the removal of what kept <lb></lb>it bent, it will reſtore it ſelf to its former <lb></lb>ſtate or poſture. </s> <s>But to return to our <lb></lb>Experiment, From thence it ſeems pro<lb></lb>bable, either that there ſucceeds no Bo<lb></lb>dy in the room of the Air drawn out of <lb></lb>our Receiver, or that it is not every Mat<lb></lb>ter that is ſubtle enough readily to paſs <lb></lb>through the Pores of Glaſs, that is al<lb></lb>ways agitated enough to produce Heat <lb></lb>where ever it is plentifully found. </s> <s>So that <lb></lb>if no <emph type="italics"></emph>Vacuum<emph.end type="italics"></emph.end> be to be admitted, this Ex<lb></lb>periment ſeems to invite us to allow a <lb></lb>great diſparity, either as to bulk, or as to <pb xlink:href="013/01/356.jpg" pagenum="326"></pb>agitation, or as to both, betwixt ſome <lb></lb>parts of the Etherial Subſtance, and thoſe <lb></lb>that are wont here below to produce Heat <lb></lb>and Fire. </s></p><p type="main"> <s>We try'd alſo what Operation the <lb></lb>drawing out of the Air would have upon <lb></lb>Camphire, that being a Body, which, <lb></lb>though not a Liquor, conſiſts of ſuch <lb></lb>Volatile or Fugitive parts, that without <lb></lb>any greater agitation then that of the open <lb></lb>Air it ſelf, they will copiouſly flie away. <lb></lb></s> <s>But we found not that even this looſe <lb></lb>Body was ſenſibly alter'd by the Exſucti<lb></lb>on of the ambient Air. </s></p><p type="main"> <s>IT may ſeem well worth trying, whether <lb></lb><arrow.to.target n="marg54"></arrow.to.target><lb></lb>or no in our exhauſted Glaſs the want <lb></lb>of an ambient Body, of the wonted thic<lb></lb>neſs of Air, would diſable even light and <lb></lb>little Animals, as Bees, and other winged <lb></lb>Inſects, to flie. </s> <s>But though we eaſily <lb></lb>foreſaw how difficult it would be to make <lb></lb>ſuch an Experiment; yet not to omit our <lb></lb>endeavors, we procur'd a large Fleſh-fly, <lb></lb>which we convey'd into a ſmall Receiver. <lb></lb></s> <s>We alſo another time ſhut into a great <lb></lb>Receiver a Humming Bee, that appear'd <lb></lb>ſtrong and lively, though we had rather <pb xlink:href="013/01/357.jpg" pagenum="327"></pb>have made the tryal with a Butter-fly, if <lb></lb>the cold Seaſon would have permitted us <lb></lb>to finde any. The Fly, af<lb></lb>ter ſome Exſuctions of the <lb></lb>Air, dropp'd down from the <lb></lb>ſide of the Glaſs whereon ſhe <lb></lb>was walking: But, that the <lb></lb>Experiment with the Bee <lb></lb>might be the more inſtructive, <lb></lb>we convey'd in with her a bun<lb></lb>dle of Flowers, which re<lb></lb>main'd ſuſpended by a ſtring <lb></lb>near the upper part of the Receiver: And <lb></lb>having provok'd the Bee, we excited her <lb></lb>to flie up and down the capacity of the <lb></lb>Veſſel, till at length, as we deſir'd, ſhe <lb></lb>lighted upon the Flowers; whereupon <lb></lb>we preſently began to draw out the Air, <lb></lb>and obſerv'd, That though for ſome time <lb></lb>the Bee ſeem'd to take no notice of it, yet <lb></lb>within awhile after ſhe did not flie, but fall <lb></lb>down from rhe Flowers, without appear<lb></lb>ing to make any uſe of her Wings to help <lb></lb>her ſelf. </s> <s>But whether this fall of the Bee, <lb></lb>and the other Inſect, proceeded from the <lb></lb>mediums being too thin for them to flie in, <lb></lb>or barely from the weakneſs, and as it were <lb></lb>ſwooning of the Animals themſelves, you <lb></lb>will eaſily gather from the following Ex<lb></lb>periment. </s></p><pb xlink:href="013/01/358.jpg" pagenum="328"></pb><p type="margin"> <s><margin.target id="marg54"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 40.</s></p><p type="main"> <s>TO ſatisfie our ſelves in ſome meaſure, <lb></lb><arrow.to.target n="marg55"></arrow.to.target><lb></lb>about the account upon which Reſpira<lb></lb>tion is ſo neceſſary to the Animals, that <lb></lb>Nature hath furniſh'd with Lungs, we <lb></lb>took (being then unable to procure any <lb></lb>other lively Bird, ſmall enough to be put <lb></lb>into the Receiver) a Lark, one of whoſe <lb></lb>Wings had been broken by a ſhot, of a <lb></lb>Man that we had ſent to provide us ſome <lb></lb>Birds for our Experiment; but notwith<lb></lb>ſtanding this hurt, the Lark was very <lb></lb>lively, and did, being put into the Recei<lb></lb>ver, divers times ſpring up in it to a good <lb></lb>height. </s> <s>The Veſſel being haſtily, but <lb></lb>carefully cloſ'd, the Pump was diligently <lb></lb>ply'd, and the Bird for a while appear'd <lb></lb>lively enough; but upon a greater Ex<lb></lb>ſuction of the Air, ſhe began manifeſtly <lb></lb>to droop and appear ſick, and very ſoon <lb></lb>after was taken with as violent and irregu<lb></lb>lar Convulſions, as are wont to be ob<lb></lb>ſerv'd in Poultry, when their heads are <lb></lb>wrung off: For the Bird threw her ſelf <lb></lb>over and over two or three times, and dy<lb></lb>ed with her Breaſt upward, her Head <lb></lb>downwards, and her Neck awry. </s> <s>And <lb></lb>though upon the appearing of theſe Con-<pb xlink:href="013/01/359.jpg" pagenum="329"></pb>vulſions, we turn'd the Stop-cock, and <lb></lb>let in the Air upon her, yet it came too <lb></lb>late; whereupon, caſting our eyes upon <lb></lb>one of thoſe accurate Dyals that go with <lb></lb>a <emph type="italics"></emph>Pendulum,<emph.end type="italics"></emph.end> and were of late ingeniouſly <lb></lb>invented by the Noble and Learned <emph type="italics"></emph>Hu<lb></lb>genius,<emph.end type="italics"></emph.end> we found that the whole Tragedy <lb></lb>had been concluded within ten Minutes of <lb></lb>an hour, part of which time had been im<lb></lb>ploy'd in cementing the Cover to the Re<lb></lb>ceiver. </s> <s>Soon after we got a Hen-ſpar<lb></lb>row, which being caught with Bird-lime <lb></lb>was not at all hurt; when we put her into <lb></lb>the Receiver, almoſt to the top of which <lb></lb>ſhe would briskly raiſe her ſelf, the Ex<lb></lb>periment being try'd with this Bird, as it <lb></lb>was with the former, ſhe ſeem'd to be <lb></lb>dead within ſeven minutes, one of which <lb></lb>were imploy'd in cementing on the Co<lb></lb>ver: But upon the ſpeedy turning of the <lb></lb>Key, the freſh Air flowing in, began ſlow<lb></lb>ly to revive her, ſo that after ſome pant<lb></lb>ings ſhe open'd her eyes, and regain'd her <lb></lb>feet, and in about a 1/4 of an hour, after <lb></lb>threatned to make an eſcape at the top of <lb></lb>the Glaſs, which had been unſtopp'd to <lb></lb>let in the freſh Air upon her: But the Re<lb></lb>ceiver being cloſ'd the ſecond time, ſhe <pb xlink:href="013/01/360.jpg" pagenum="330"></pb>was kill'd with violent Convulſions, <lb></lb>within five Minutes from the beginning <lb></lb>of the Pumping. </s></p><p type="margin"> <s><margin.target id="marg55"></margin.target><emph type="italics"></emph>Experi<lb></lb>ment<emph.end type="italics"></emph.end> 41.</s></p><p type="main"> <s>A while after we put in a Mouſe, new<lb></lb>ly taken, in ſuch a Trap as had rather af<lb></lb>frighted then hurt him; vvhil'ſt he vvas <lb></lb>leaping up very high in the Receiver, vve <lb></lb>faſten'd the Cover to it, expecting that <lb></lb>an Animal uſed to live in narrow holes <lb></lb>vvith very little freſh Air, vvould endure <lb></lb>the vvant of it better then the lately men<lb></lb>tion'd Birds: But though, for a vvhile af<lb></lb>ter the Pump vvas ſet avvork, he conti<lb></lb>nued leaping up as before; yet 'tvvas not <lb></lb>long ere he began to appear ſick and gid<lb></lb>dy, and to ſtagger, after vvhich he fell <lb></lb>dovvn as dead, but vvithout ſuch violent <lb></lb>Convulſions as the Birds died vvith. <lb></lb></s> <s>Whereupon, haſtily turning the Key, we <lb></lb>let in ſome freſh Air upon him, by vvhich <lb></lb>he recovered, after a vvhile, his ſenſes and <lb></lb>his feet, but ſeem'd to continue vveak and <lb></lb>ſick: But at length, grovving able to <lb></lb>skip as formerly, the Pump vvas plyed <lb></lb>again for eight minutes, about the mid<lb></lb>dle of vvhich ſpace, if not before, a very <lb></lb>little Air by a miſchance got in at the <lb></lb>Stop-cock; and about tvvo minutes after <lb></lb>that, the Mouſe divers times leap'd up <pb xlink:href="013/01/361.jpg" pagenum="331"></pb>lively enough, though after about two mi<lb></lb>nutes more he fell down quite dead, yet <lb></lb>with Convulſions far milder then thoſe <lb></lb>wherewith the two Birds expired. </s> <s>This <lb></lb>alacrity ſo little before his death, and his <lb></lb>not dying ſooner then at the end of the <lb></lb>eighth minute, ſeem'd aſcribable to the <lb></lb>Air (how little ſoever) that ſlipt into the <lb></lb>Receiver. </s> <s>For the firſt time, thoſe Con<lb></lb>vulſions (that, if they had not been ſud<lb></lb>denly remedied, had immediately diſ<lb></lb>patch'd him) ſeiſ'd on him in ſix minutes <lb></lb>after the Pump began to be ſet awork. <lb></lb></s> <s>Theſe Experiments ſeem'd the more <lb></lb>ſtrange, in regard, that during a great part of <lb></lb>thoſe few minutes the Engine could but <lb></lb>conſiderably rarefie the Air (and that too, <lb></lb>but by degrees) and at the end of them <lb></lb>there remain'd in the Receiver no incon<lb></lb>ſiderable quantity; as may appear by what <lb></lb>we have formerly ſaid of our not being <lb></lb>able to draw down Water in a Tube, with<lb></lb>in much leſs then a Foot of the bottom: <lb></lb>with which we likewiſe conſider'd, that by <lb></lb>the exſuction of the Air and interſper<lb></lb>ſed Vapors, there was left in the Recei<lb></lb>ver a ſpace ſome hundreds of times ex<lb></lb>ceeding the bigneſs of the Animal, to re<lb></lb>ceive the fuliginous Steams, from which, <pb xlink:href="013/01/362.jpg" pagenum="332"></pb>expiration diſcharges the Lungs; and, <lb></lb>which in the other caſes hitherto known, <lb></lb>may be ſuſpected, for want of room, to <lb></lb>ſtifle thoſe Animals that are cloſely pent <lb></lb>up in too narrow Receptacles. </s></p><p type="main"> <s>I forgot to mention, that having cauſ'd <lb></lb>theſe three Creatures to be open'd, I <lb></lb>could, in ſuch ſmall Bodies, diſcover lit<lb></lb>tle of what we ſought for, and what we <lb></lb>might poſſibly have found in larger Ani<lb></lb>mals; for though the Lungs of the Birds <lb></lb>appear'd very red, and as it were inflam'd, <lb></lb>yet that colour being uſual enough in the <lb></lb>Lungs of ſuch winged Creatures, deſerves <lb></lb>not ſo much our notice, as it does, That <lb></lb>in almoſt all the deſtructive Experiments <lb></lb>made in our Engine, the Animals appear'd <lb></lb>to die with violently Convulſive Moti<lb></lb>ons: From which, whether Phyſicians can <lb></lb>gather any thing towards the Diſcovery <lb></lb>of the Nature of Convulſive Diſtem<lb></lb>pers, I leave to them to conſider. </s></p><p type="main"> <s>Having proceeded thus far, though (as <lb></lb>we have partly intimated already) there <lb></lb>appear'd not much cauſe to doubt, but <lb></lb>that the death of the fore-mention'd Ani<lb></lb>mals proceeded rather from the want of <lb></lb>Air, then that the Air was over-clogg'd <lb></lb>by the ſteams of their Bodies, exquiſite-<pb xlink:href="013/01/363.jpg" pagenum="333"></pb>ly pent up in the Glaſs; yet I, that love <lb></lb>not to believe any thing upon Conje<lb></lb>ctures, when by a not over-difficult Ex<lb></lb>periment I can try whether it be True or <lb></lb>no, thought it the ſafeſt way to obviate <lb></lb>Objections, and remove Scruples, by ſhut<lb></lb>ting up another Mouſe as cloſe as I could <lb></lb>in the Receiver, wherein it liv'd above <lb></lb>three quarters of an hour; and might pro<lb></lb>bably have done ſo much longer, had not <lb></lb>a <emph type="italics"></emph>Virtuoſo<emph.end type="italics"></emph.end> of quality, who in the mean <lb></lb>while chanc'd to make me a Viſit, deſir'd <lb></lb>to ſee whether or no the Mouſe could be <lb></lb>kill'd by the exſuction of the ambient Air, <lb></lb>whereupon we thought fit to open, for a <lb></lb>little while, an intercourſe betwixt the <lb></lb>Air in the Receiver, and that without it, <lb></lb>that the Mouſe might thereby (if it were <lb></lb>needful for him) be refreſh d, and yet we <lb></lb>did this without uncementing the Cover <lb></lb>at the top, that it might not be objected, <lb></lb>that perhaps the Veſſel was more cloſely <lb></lb>ſtopp'd for the exſuction of the Air then <lb></lb>before. </s></p><p type="main"> <s>The Experiment had this event, that <lb></lb>after the Mouſe had liv'd ten Minutes, <lb></lb>(which we aſcrib'd to this, that the Pump, <lb></lb>for want of having been lately Oyl'd, <lb></lb>could move but ſlowly, and could not by <pb xlink:href="013/01/364.jpg" pagenum="334"></pb>him that manag'd it, be made to work as <lb></lb>nimbly as it was wont) at the end of that <lb></lb>time he dy'd with Convulſive Fits, where<lb></lb>in he made two or three bounds into the <lb></lb>Air, before he fell down dead. </s></p><p type="main"> <s>Nor was I content with this, but for <lb></lb>Your Lordſhips further ſatisfaction, and <lb></lb>my own, I cauſ'd a Mouſe, that was very <lb></lb>hungry, to be ſhut in all Night, with a <lb></lb>Bed of Paper for him to reſt upon: And <lb></lb>to be ſure that the Receiver was well <lb></lb>cloſ'd, I cauſ'd ſome Air to be drawn out <lb></lb>of it, whereby, perceiving that there <lb></lb>was no ſenſible leak, I preſently re-ad<lb></lb>mitted the Air at the Stop-cock, leſt the <lb></lb>want of it ſhould harm the little Animal; <lb></lb>and then I cauſ'd the Engine to be kept <lb></lb>all Night by the Fire ſide, to keep him <lb></lb>from being deſtroy'd by the immoderate <lb></lb>cold of the Froſty Night. </s> <s>And this care <lb></lb>ſucceeded ſo well, that the next Morning <lb></lb>I found that the Mouſe not onely was a<lb></lb>live, but had devour'd a good part of the <lb></lb>Cheeſe that had been put in with him. </s> <s>And <lb></lb>having thus kept him alive full twelve <lb></lb>hours, or better, we did, by ſucking out <lb></lb>part of the Air, bring him to droop, and <lb></lb>to appear ſwell'd; and by letting in the <lb></lb>Air again, we ſoon reduc'd him to his for<lb></lb>mer livelineſs. </s></p><pb xlink:href="013/01/365.jpg" pagenum="335"></pb><p type="main"> <s><emph type="center"></emph><emph type="italics"></emph>A Digreſsion containing ſome <lb></lb>Doubts touching Reſpi<lb></lb>ration.<emph.end type="italics"></emph.end><emph.end type="center"></emph.end></s></p><p type="main"> <s>I Fear Your Lordſhip will now expect, <lb></lb>that to theſe Experiments I ſhould add <lb></lb>my Reflections on them, and attempt, <lb></lb>by their aſſiſtance, to reſolve the Diffi<lb></lb>culties that occur about Reſpiration; ſince <lb></lb>at the beginning I acknowledg'd a further <lb></lb>Enquiry into the Nature of that, to have <lb></lb>been my Deſign in the related Tryals. <lb></lb></s> <s>But I have yet, becauſe of the inconve<lb></lb>nient Seaſon of the Year, made ſo few <lb></lb>Experiments, and have been ſo little ſa<lb></lb>tisfied by thoſe I have been able to make, <lb></lb>that they have hitherto made Reſpiration <lb></lb>appear to me rather a more, then a leſs <lb></lb>Myſterious thing, then it did before. </s> <s>But <lb></lb>yet, ſince they have furniſh'd me with <lb></lb>ſome ſuch new Conſiderations, concern<lb></lb>ing the uſe of the Air, as confirms me in <lb></lb>my Diffidence of the Truth of what is <lb></lb>commonly believ'd touching that matter; <lb></lb>That I may not appear ſullen or lazy, I <lb></lb>am content not to decline employing a <pb xlink:href="013/01/366.jpg" pagenum="336"></pb>few hours in ſetting down my Doubts, in <lb></lb>preſenting Your Lordſhip ſome Hints, <lb></lb>and in conſidering whether the Tryals <lb></lb>made in our Engine, will at leaſt aſſiſt us <lb></lb>to diſcover wherein the Deficiency lies <lb></lb>that needs to be ſupply'd. </s></p><p type="main"> <s>And this, My Lord, being all my pre<lb></lb>ſent Deſign, I ſuppoſe You will not ex<lb></lb>pect that (as if You knew not, or had for<lb></lb>gotten what Anatomiſts are wont to <lb></lb>teach) I ſhould entertain You with a need<lb></lb>leſs Diſcourſe of the Organs of Reſpira<lb></lb>tion, and the variety of their Structure in <lb></lb>ſeveral Animals; though if it were ne<lb></lb>ceſſary, and had not been perform'd by o<lb></lb>thers, I ſhould think, with <emph type="italics"></emph>Galen,<emph.end type="italics"></emph.end> that by <lb></lb><arrow.to.target n="marg56"></arrow.to.target><lb></lb>treating of the Fabricks of living Bodies, <lb></lb>I might compoſe Hymns to the wiſe Au<lb></lb>thor of Nature, who, in the excellent con<lb></lb>trivance of the Lungs, and other parts of <lb></lb>(thoſe admirable Engines) Animals, ma<lb></lb>nifeſts himſelf to be indeed what the Elo<lb></lb>quent Prophet moſt juſtly ſpeaks him, <lb></lb><emph type="italics"></emph>Wonderful in Counsel, and excellent in<emph.end type="italics"></emph.end><lb></lb><arrow.to.target n="marg57"></arrow.to.target><lb></lb><emph type="italics"></emph>working.<emph.end type="italics"></emph.end></s></p><p type="margin"> <s><margin.target id="marg56"></margin.target><emph type="italics"></emph>Galenus de <lb></lb><gap></gap>, Part: <lb></lb>lib. <emph.end type="italics"></emph.end> 3.</s></p><p type="margin"> <s><margin.target id="marg57"></margin.target><gap></gap>a.28.29.</s></p><p type="main"> <s>Nor ſhall we any further meddle with <lb></lb>thoſe Controverſies ſo much agitated a<lb></lb>mong the Moderns, namely, <emph type="italics"></emph>Whether the <lb></lb>motion of the Lungs in Reſpiration be their<emph.end type="italics"></emph.end><pb xlink:href="013/01/367.jpg" pagenum="337"></pb><emph type="italics"></emph>own, or but conſequent to the motion of the <lb></lb>Thorax, Diaphragme, and<emph.end type="italics"></emph.end> (as ſome Learn<lb></lb>ed Men would have it) <emph type="italics"></emph>the Abdomen; And, <lb></lb>Whence it is that the Air ſwells the Lungs <lb></lb>in Inſpiration<emph.end type="italics"></emph.end> any further then they may <lb></lb>receive light from our Engine: But that <lb></lb>it may appear what kinde of ſervice it is <lb></lb>that may be expected from it on this oc<lb></lb>caſion, we muſt premiſe a few Words to <lb></lb>ſhew wherein the ſtrength of the Obje<lb></lb>ction we are to anſwer, lies. </s> <s>In favor then <lb></lb>of thoſe that would have the Lungs ra<lb></lb>ther paſſive then active in the buſineſs of <lb></lb>Reſpiration, it may againſt the common <lb></lb>opinion be alledg'd, That as the Lungs be<lb></lb>ing deſtitute of Muſcles and of Fibres, <lb></lb>are unfit to dilate themſelves; ſo it ap<lb></lb>pears, that without the motion of the <lb></lb><emph type="italics"></emph>Thorax<emph.end type="italics"></emph.end> they would not be fill'd with Air. <lb></lb></s> <s>Since as our Learned Friend Dr. <emph type="italics"></emph>High<lb></lb>more<emph.end type="italics"></emph.end> has well (and congruouſly, to what <lb></lb>our ſelves have purpoſely try'd) ob<lb></lb>ſerv'd, if a live Dog have a great wound <lb></lb>made in his Cheſt, the Lobes of the <lb></lb>Lungs on that ſide of the <emph type="italics"></emph>Mediaſti<lb></lb>num<emph.end type="italics"></emph.end> will ſubſide and lie ſtill; the <emph type="italics"></emph>Tho<lb></lb>rax<emph.end type="italics"></emph.end> and the Lobes on the other ſide <lb></lb>of the <emph type="italics"></emph>Mediaſtinum,<emph.end type="italics"></emph.end> continuing their <lb></lb>former motion. </s> <s>And if ſuddenly at once <pb xlink:href="013/01/368.jpg" pagenum="338"></pb>the Muſcles of the Cheſt be on both <lb></lb>ſides diſſected, upon the Ingreſs of the <lb></lb>Air, the whole Lungs, though untouch'd, <lb></lb>will remain moveleſs, at leaſt, as to any ex<lb></lb>panſion or contraction of their ſubſtance. </s></p><p type="main"> <s>To which we may adde the Obſervati<lb></lb>on of the diligent <emph type="italics"></emph>Bartholinus,<emph.end type="italics"></emph.end> who af<lb></lb>firms the like of the <emph type="italics"></emph>Diaphragme<emph.end type="italics"></emph.end> al<lb></lb>ſo, namely, That it being wounded, the <lb></lb>Lungs will fall together, and the Reſpi<lb></lb>ration ceaſe, which my Experiments op<lb></lb>poſe not, provided the Wound be any <lb></lb>thing great. </s> <s>And indeed the <emph type="italics"></emph>Diaphragme<emph.end type="italics"></emph.end><lb></lb>ſeems the principal Inſtrument of ordina<lb></lb>ry and gentle Reſpiration, although to <lb></lb>reſtrain'd Reſpiration (if I may ſo call <lb></lb>it) the intercoſtal Muſcles, and perhaps <lb></lb>ſome others may be allowed eminently to <lb></lb>concur. </s> <s>But the chief of the Contro<lb></lb>verſies formerly pointed at, is not yet de<lb></lb>cided, namely, what it is that conveys the <lb></lb>Air into the Lungs. </s> <s>For when, to coun<lb></lb>terballance all that has been alledg'd, thoſe <lb></lb>that plead for the Lungs, demand what it <lb></lb>is that ſhould bring the Air into the <lb></lb>Lungs, if themſelves do not attract it, <lb></lb>their Antagoniſts diſagree about the Re<lb></lb>ply. </s> <s>For when to this queſtion ſome of <lb></lb>the beſt Modern Philoſophers anſwer, <pb xlink:href="013/01/369.jpg" pagenum="339"></pb>that by the dilatation of the Cheſt the <lb></lb>contiguous Air is thruſt away, and that <lb></lb>preſſing upon the next Air to it, and ſo <lb></lb>onwards, the Propulſion is continued till <lb></lb>the Air be driven into the Lungs, and ſo <lb></lb>dilate them: When this (I ſay) is an<lb></lb>ſwered, it is Objected even by <emph type="italics"></emph>Bartholine<emph.end type="italics"></emph.end><lb></lb>himſelf, as a convincing Reply, that, ac<lb></lb>cording to this Doctrine, a Man could not <lb></lb>fetch his Breath from a great Veſſel full of <lb></lb>Air, with a ſlender Neck, becauſe, that <lb></lb>when his Mouth covers the Orifice of the <lb></lb>Neck, the dilatation of his <emph type="italics"></emph>Thorax<emph.end type="italics"></emph.end> could <lb></lb>not propell the Air in the Veſſel into his <lb></lb>Lungs, by reaſon of its being ſeparated <lb></lb>by the incloſing Veſſel from the ambient <lb></lb>Air; and yet, ſay they, Experience wit<lb></lb>neſſes that out of ſuch a Veſſel a Man may <lb></lb>ſuck Air. </s> <s>But of this difficulty our Engine <lb></lb>furniſhes us with an eaſie Solution, ſince <lb></lb>many of the former Experiments have ma<lb></lb>nifeſted, That in the caſe propoſed, there <lb></lb>needs not be made any (though 'tis true <lb></lb>that in ordinary Reſpiration there is wont <lb></lb>to be made ſome) propulſion of the Air by <lb></lb>the ſwelling <emph type="italics"></emph>Thorax<emph.end type="italics"></emph.end> or <emph type="italics"></emph>Abdomen<emph.end type="italics"></emph.end> into the <lb></lb>Lungs; ſince upon the bare Dilatation of <lb></lb>the <emph type="italics"></emph>Thorax,<emph.end type="italics"></emph.end> the Spring of that internal <lb></lb>Air, or halituous ſubſtance that is wont <pb xlink:href="013/01/370.jpg" pagenum="340"></pb>to poſſeſs as much of the Cavity of the <lb></lb>Cheſt as the Lungs fill not up, being much <lb></lb>weaken'd, the external and contiguous <lb></lb>Air muſt neceſſarily preſs in at the open <lb></lb>Winde-Pipe into the Lungs, as finding <lb></lb>there leſs reſiſtance then any where elſe a<lb></lb>bout it. </s></p><p type="main"> <s>And hence (by the way) we may derive <lb></lb>a new aſſiſtance to judge of that famous <lb></lb>Controverſie diſputed among Naturaliſts <lb></lb>and Phyſitians, ever ſince <emph type="italics"></emph>Galens<emph.end type="italics"></emph.end> time, <lb></lb>ſome maintaining that the Cheſt, with the <lb></lb>contained Lungs, may be reſembled to a <lb></lb>pair of Bellows, which comes therefore <lb></lb>to be fill'd becauſe it was dilated: And o<lb></lb>thers pleading to have the compariſon <lb></lb>made to a Bladder, which is therefore di<lb></lb>lated becauſe it is fill'd. </s> <s>For as to the <lb></lb><emph type="italics"></emph>Thorax,<emph.end type="italics"></emph.end> it ſeems evident from what has <lb></lb>been lately ſaid, that it, like a pair of Bel<lb></lb>lows, happens to be partly fill'd with Air, <lb></lb>but becauſe it was dilated: But as for the <lb></lb>Lungs themſelves, who want Fibres to <lb></lb>diſtend them, they may fitly enough be <lb></lb>compar'd to a Bladder; ſince they are di<lb></lb>lated by being fill'd, namely, by that Air <lb></lb>which ruſhes into them upon the dilatation <lb></lb>of the Cheſt, in whoſe increaſed Cavity <lb></lb>it findes (as we freſhly noted) leſs reſiſt-<pb xlink:href="013/01/371.jpg" pagenum="341"></pb>ance to its Spring then elſewhere. </s> <s>And <lb></lb>this brings into my minde that ſtrange <lb></lb>Obſervation of <emph type="italics"></emph>Nicolaus Fontanus,<emph.end type="italics"></emph.end> a Phy<lb></lb><arrow.to.target n="marg58"></arrow.to.target><lb></lb>ſitian at <emph type="italics"></emph>Amſterdam,<emph.end type="italics"></emph.end> who teſtifies, That <lb></lb>in a Boy of the ſame Town, four years <lb></lb>old, there was found, inſtead of Lungs, a <lb></lb>certain Membranous Bladder; which be<lb></lb>ing fill'd with Wind, and furniſh'd with <lb></lb>little Veins, had its origination from the <lb></lb>Wind-Pipe it ſelf; which being ſuppoſ'd <lb></lb>true, how well it will agree with moſt of <lb></lb>the Opinions touching Reſpiration, I leave <lb></lb>to be conſidered. </s></p><p type="margin"> <s><margin.target id="marg58"></margin.target><emph type="italics"></emph>Fontanus ><lb></lb>apud<emph.end type="italics"></emph.end> Bar<lb></lb>tholin: lib.<lb></lb>2. cap. 9.</s></p><p type="main"> <s>And thus may the grand Objection of <lb></lb><emph type="italics"></emph>Bartholine,<emph.end type="italics"></emph.end> and others, be anſwered: But <lb></lb>I leave to Anatomiſts to conſider what is <lb></lb>to be ſaid to ſome Obſervations that ſeem <lb></lb>to contradict thoſe Anatomical Experi<lb></lb>ments already mention'd: Such was par<lb></lb>ticularly that which I remember I have <lb></lb>read in <emph type="italics"></emph>Sennertus<emph.end type="italics"></emph.end> (from the obſervation of <lb></lb>his Father-in-law <emph type="italics"></emph>Schato<emph.end type="italics"></emph.end>) of a Melancho<lb></lb>ly Student, who having ſtabb'd himſelf, <lb></lb>and pierced the <emph type="italics"></emph>Diaphragme<emph.end type="italics"></emph.end> in the thinner <lb></lb>or tendonous part (call'd by many the <lb></lb>Nervous Circle) lived ſeven Moneths af<lb></lb>ter he had ſo wounded himſelf, though af<lb></lb>ter his death (preceded by violent Vomit-<pb xlink:href="013/01/372.jpg" pagenum="342"></pb>ings) the Wound (perchance dilated by <lb></lb>thoſe ſtrainings) appear'd ſo great, that <lb></lb>the whole Stomack was found to have got <lb></lb>in by it into the left ſide of the <emph type="italics"></emph>Thorax.<emph.end type="italics"></emph.end><lb></lb>And ſuch alſo was the accident that hap<lb></lb>pen'd to a Noble Man, whom I remem<lb></lb>ber I have ſeen, and who is yet alive, in <lb></lb>whoſe Cheſt there has, for theſe many <lb></lb>years, remain'd a hole ſo great, that the <lb></lb>motion of his Heart may be perceiv'd by <lb></lb>it. </s> <s>Theſe (I ſay) and ſome other Obſer<lb></lb>vations, I ſhall now forbear to inſiſt on, <lb></lb>becauſe I hold it not unfit, before we <lb></lb>come to conſider the uſe of Reſpiration, <lb></lb>that we acquaint Your Lordſhip with an <lb></lb>Ingenious Conjecture, that was made at <lb></lb>the cauſe of the haſty death of the Ani<lb></lb>mals our Engine kill'd: namely, That it <lb></lb>was not the want of Air that deſtroy'd <lb></lb>them, but the Preſſure of the innate Air <lb></lb>in the cavity of the Cheſt; as if the <lb></lb>Spring of this Air being no longer coun<lb></lb>terballanc'd by the ambient Air, was there<lb></lb>by become ſo ſtrong, that it kept the <lb></lb><emph type="italics"></emph>Thorax<emph.end type="italics"></emph.end> forcibly diſtended, and hinder'd its <lb></lb>wonted contraction; and ſo compreſſ'd <lb></lb>the Lungs and their Veſſels, as to obſtruct <lb></lb>the Circulation of the Blood. </s> <s>And this <pb xlink:href="013/01/373.jpg" pagenum="343"></pb>Conjecture, as it is ſpecious enough, ſo I <lb></lb>might have admitted it for true; but that <lb></lb>I conſider'd, that (not to mention that <lb></lb>one, eſpecially of the Animals kill'd in <lb></lb>our Engine, ſeem'd manifeſtly for a pret<lb></lb>ty while, and not long before he dy'd, to <lb></lb>move his <emph type="italics"></emph>Thorax,<emph.end type="italics"></emph.end> as if he exerciſ'd Reſpi<lb></lb>ration) the diligent <emph type="italics"></emph>Wallæus<emph.end type="italics"></emph.end> relates, That <lb></lb>he divers times obſerv'd, in the Diſſecti<lb></lb>on of live Bodies, that the Membrane <lb></lb>that inveſts the Lungs, had Pores in it <lb></lb>as big as the larger ſort of Peas, which a<lb></lb>grees with the Obſervations of Chyrur<lb></lb>gions and Phyſitians, <emph type="italics"></emph>viz.<emph.end type="italics"></emph.end></s><s> That matter <lb></lb>collected in the <emph type="italics"></emph>Thorax,<emph.end type="italics"></emph.end> has penetrated in<lb></lb>to the Lungs, and been diſcharged by <lb></lb>coughing. </s> <s>And I remember too, that moſt <lb></lb>of the Animals we kill'd in our Engine <lb></lb>were Birds, of whoſe Lungs <emph type="italics"></emph>Harvey<emph.end type="italics"></emph.end><lb></lb>ſomewhere informs us, That he ob<lb></lb>ſerv'd them very manifeſtly to open at <lb></lb>their Extremities into the <emph type="italics"></emph>Abdomen.<emph.end type="italics"></emph.end><lb></lb>And by ſuch Perforations we may well <lb></lb>ſuppoſe the paſſage free betwixt the exter<lb></lb>nal Air and that in the <emph type="italics"></emph>Abdomen:<emph.end type="italics"></emph.end> But this <lb></lb>Conjecture may be further conſider'd. <lb></lb></s> <s>Beſides, to ſhow that the Animals that <lb></lb>died in our Glaſſes, need not be ſuppoſ'd <pb xlink:href="013/01/374.jpg" pagenum="344"></pb>to have been kill'd by the want of Air, we <lb></lb>foreſee another Argument that we muſt <lb></lb>deal ſo ingeniouſly with Your Lordſhip, <lb></lb>as not to conceal. </s> <s>You very well know, <lb></lb>that beſides the generality of the <lb></lb>Schools, there are many new Philoſophers <lb></lb>who, though they diſſent from the old <lb></lb>Peripateticks in other things, do, as they, <lb></lb>deny the poſſibility of a <emph type="italics"></emph>Vacuum;<emph.end type="italics"></emph.end> and <lb></lb>hold, that thoſe ſpaces which are devoid <lb></lb>of Air, and other groſſer Bodies, are all <lb></lb>of them exactly repleniſhed with a certain <lb></lb>Etherial Matter, ſo thin and ſubtle, that <lb></lb>it can freely permeate the Pores of the <lb></lb>compactedſt and cloſeſt Bodies, and ev'n <lb></lb>of Glaſs it ſelf. </s> <s>Now ſome of thoſe Na<lb></lb>turaliſts that are of this perſwaſion may <lb></lb>object, That the Animals that died in our <lb></lb>Receivers, did ſo, not ſo much for lack of <lb></lb>Air, as by reaſon that the Air that was <lb></lb>pump'd out was neceſſarily ſucceeded by <lb></lb>an Etherial Subſtance; which conſiſting of <lb></lb>parts vehemently agitated, and ſo very <lb></lb>ſmall, as without reſiſtance to paſs in and <lb></lb>out through the very Pores of Glaſs; it <lb></lb>may well be ſuppoſ'd, that a conſiderable <lb></lb>quantity of this reſtleſs and ſubtle Mat<lb></lb>ter, meeting together in the Receiver, <pb xlink:href="013/01/375.jpg" pagenum="345"></pb>with the exceſſive heat of it, may be <lb></lb>quickly able to deſtroy a little Animal, or <lb></lb>at leaſt, make the Air too intemperately <lb></lb>hot to be fit for Reſpiration. </s></p><p type="main"> <s>But though this be a Difficulty not ſo <lb></lb>eaſily to be reſolv'd without the aſſiſtance <lb></lb>of our Engine, yet I ſuppoſe we have al<lb></lb>ready anſwer'd the Objection by our 38<emph type="sup"></emph>th<emph.end type="sup"></emph.end><lb></lb>and 39<emph type="sup"></emph>th<emph.end type="sup"></emph.end> Experiments; which though we <lb></lb>made partly for other purpoſes, yet we <lb></lb>premiſ'd them onely to clear up the diffi<lb></lb>culty propoſ'd. </s></p><p type="main"> <s>Another ſuſpition we ſhould have en<lb></lb>tertain'd concerning the death of our Ani<lb></lb>mals, namely, That upon the ſudden re<lb></lb>moval of the wonted preſſure of the am<lb></lb>bient Air, the warm Blood of thoſe Ani<lb></lb>mals was brought to an Efferveſcence or <lb></lb>Ebullition, or at leaſt ſo vehemently ex<lb></lb>panded, as to diſturb the Circulation of <lb></lb>the Blood, and ſo diſorder the whole Oe<lb></lb>conomy of the Body. (This (I ſay) I <lb></lb>ſhould have had ſome ſuſpition of) but <lb></lb>that Animals of a hot Conſtitution are <lb></lb>not the ſole ones that cannot in our ex<lb></lb>hauſted Engine exerciſe the Function of <lb></lb>Life. </s> <s>But I muſt not now dwell upon <lb></lb>matters of this nature, becauſe I think <lb></lb>it high time to proceed to the conſiderati-<pb xlink:href="013/01/376.jpg" pagenum="346"></pb>on of the principal ſubject of our Engine, <lb></lb>namely, The uſe of Reſpiration; or ra<lb></lb>ther, The uſe of the Air in Reſpiration. <lb></lb></s> <s>For whereas of the divers uſes of it men<lb></lb>tion'd by Anatomiſts the moſt, ſuch as <lb></lb>the Production and Modulation of the <lb></lb>Voice by the Eliſion of the Air, the <emph type="italics"></emph>La<lb></lb>rynx<emph.end type="italics"></emph.end> &c. </s> <s>the expulſion of Excrements <lb></lb>by Coughing, the conveying in of Odours <lb></lb>by Inſpiration, and ſome others, rather <lb></lb>convenient for the well being of an Ani<lb></lb>mal, then abſolutely neceſſary to his Life: <lb></lb>Whereas (I ſay) the other uſes are ſuch as <lb></lb>we have ſaid, The great <emph type="italics"></emph>Hippocrates<emph.end type="italics"></emph.end> him<lb></lb>ſelf gives this notable Teſtimony to the <lb></lb>uſe of the Air, as to Animals endow'd <lb></lb>with Lungs, <emph type="italics"></emph>Mortalibus<emph.end type="italics"></emph.end> (ſays he) <emph type="italics"></emph>hic<emph.end type="italics"></emph.end> (ſpi<lb></lb>ritus) <emph type="italics"></emph>tum vitæ, tum morborum ægrotis cau<lb></lb>ſa eſt. </s> <s>Tantáque corporibus omnibus ſpi<lb></lb>ritûs ineſt neceßitas, ut ſiquidem aliis om<lb></lb>nibus & cibis & potionibus, quis abſtineat, <lb></lb>duos <expan abbr="tamẽ">tamen</expan> aut tres, vel plures dies poßit vi<lb></lb>tam ducere: At ſi quis ſpiritus in corpus <lb></lb>vias intercipiat, vel exiguâ diei parte, ho<lb></lb>mini pereundum ſit; Adeo neceſſarius eſt <lb></lb>uſus ſpiritûs in corpore. </s> <s>Ad hæc quo〈qué〉, <lb></lb>quum omnibus aliis actionibus homines qui<lb></lb>eſcant, quod mutationibus innumer is vita <lb></lb>ſit expoſita, ab hâc tamen ſolâ actione nun-<emph.end type="italics"></emph.end><pb xlink:href="013/01/377.jpg" pagenum="347"></pb><emph type="italics"></emph>quam deſiſtant animantia, quin aut ſpiritum <lb></lb>adducant, aut reddant.<emph.end type="italics"></emph.end></s></p><p type="main"> <s>But touching the account upon which <lb></lb>the Inſpiration and Exſpiration of Air <lb></lb>(both which are comprehended in <foreign lang="grc">ἀγαπνο<gap></gap></foreign>, <lb></lb>Reſpiration) is ſo neceſſary to Life, both <lb></lb>Naturaliſts and Phyſitians do ſo diſagree, <lb></lb>that it will be very difficult either to re<lb></lb>concile their Opinions, or determine their <lb></lb>Controverſies. </s></p><p type="main"> <s>For firſt, Many there are who think <lb></lb>the chief (if not ſole) uſe of Reſpiration <lb></lb>to be the Cooling and tempering of that <lb></lb>Heat in the Heart and Blood, which other<lb></lb>wiſe would be immoderate: And this O<lb></lb>pinion, not onely ſeems to be moſt recei<lb></lb>ved amongſt Scholaſtick Writers, but di<lb></lb>vers of the new Philoſophers, Carteſians, <lb></lb>and others, admitted with ſome variation; <lb></lb>teaching, That the Air is neceſſary, by its <lb></lb>coldneſs, to condenſe the Blood that paſ<lb></lb>ſes out of the right Ventricle of the <lb></lb>Heart into the Lungs, that thereby it may <lb></lb>obtain ſuch a conſiſtence, as is requiſite <lb></lb>to make it fit Fewel for the vital Fire or <lb></lb>Flame, in the left Ventricle of the heart. <lb></lb></s> <s>And this Opinion ſeems favor'd by this, <lb></lb>That Fiſhes, and other cold Creatures, <lb></lb>whoſe Hearts have but one cavity, are al-<pb xlink:href="013/01/378.jpg" pagenum="348"></pb>ſo unprovided of Lungs, and by ſome o<lb></lb>ther conſiderations. </s> <s>But though it need <lb></lb>not be deny'd, that the inſpir'd Air may <lb></lb>ſometimes be of uſe by refrigerating the <lb></lb>Heart; yet (againſt the Opinion that makes <lb></lb>this Refrigeration, the moſt genuine and <lb></lb>conſtant uſe of the Air) it may be Obje<lb></lb>cted, That divers cold Creatures (ſome <lb></lb>of which, as particularly Frogs, live in <lb></lb>the Water) have yet need of Reſpiration, <lb></lb>which ſeems not likely to be needed for <lb></lb>Refrigeration by them that are deſtitute of <lb></lb>any ſenſible heat, and beſides, live in the <lb></lb>cold Water: That even decrepid old <lb></lb>Men, whoſe natural heat is made very <lb></lb>languid, and almoſt extinguiſh'd by rea<lb></lb>ſon of age, have yet a neceſſity of fre<lb></lb>quent Reſpiration: That a temperate Air <lb></lb>is fitteſt for the generality of breathing <lb></lb>Creatures; and as an Air too hot, ſo al<lb></lb>ſo an Air too cold, may be inconvenient <lb></lb>for them (eſpecially, if they be troubled <lb></lb>with an immoderate degree of the ſame <lb></lb>Quality which is predominant in the Air:) <lb></lb>That in ſome Diſeaſes the natural heat is <lb></lb>ſo weaken'd, that in caſe the uſe of Reſpi<lb></lb>ration were to cool, it would be more <lb></lb>hurtful then beneficial to breath; and the <lb></lb>ſuſpending of the Reſpiration, may ſup-<pb xlink:href="013/01/379.jpg" pagenum="349"></pb>ply the place of thoſe very hot Medicines <lb></lb>that are wont to be employ'd in ſuch Di<lb></lb>ſtempers: That Nature might much bet<lb></lb>ter have given the Heart but a moderate <lb></lb>heat, then ſuch an exceſſive one, as needs <lb></lb>to be perpetually cool'd, to keep it from <lb></lb>growing deſtructive; which the gentle, <lb></lb>and not the burning heat of an Animals <lb></lb>Heart, ſeems not intenſe enough ſo indi<lb></lb>ſpenſably to require. </s> <s>Theſe, and other <lb></lb>Objections, might be oppoſ'd, and preſſ'd <lb></lb>againſt the recited Opinion: But we ſhall <lb></lb>not inſiſt on them, but onely adde to <lb></lb>them, That it appears not by our fore<lb></lb>going Experiments (I mean the 38<emph type="sup"></emph>th<emph.end type="sup"></emph.end> and <lb></lb>39<emph type="sup"></emph>th<emph.end type="sup"></emph.end>) that in our exhauſted Receiver, <lb></lb>where yet Animals die ſo ſuddenly for <lb></lb>want of Reſpiration, the ambient Body is <lb></lb>ſenſibly hotter then the common Air. </s></p><p type="main"> <s>Other Learned Men there are, who will <lb></lb>have the very ſubſtance of the Air to get <lb></lb>in by the Veſſels of the Lungs, to the <lb></lb>left Ventricle of the Heart, not onely to <lb></lb>temper its heat, but to provide for the <lb></lb>generation of Spirits. </s> <s>And theſe alledge <lb></lb>for themſelves the Authority of the An<lb></lb>tients, among whom <emph type="italics"></emph>Hippocrates<emph.end type="italics"></emph.end> ſeems <lb></lb>manifeſtly to favor their Opinion; and <lb></lb>both <emph type="italics"></emph>Ariſtotle<emph.end type="italics"></emph.end> and <emph type="italics"></emph>Galen<emph.end type="italics"></emph.end> do ſometimes <pb xlink:href="013/01/380.jpg" pagenum="350"></pb>(for methinks they ſpeak doubtfully e<lb></lb>nough) appear inclinable to it. </s> <s>But for <lb></lb>ought ever I could ſee in Diſſections, it is <lb></lb>very difficult to make out, how the Air is <lb></lb>convey'd into the left Ventricle of the <lb></lb>Heart, eſpecially the <emph type="italics"></emph>Syſtole<emph.end type="italics"></emph.end> and <emph type="italics"></emph>Diaſtole<emph.end type="italics"></emph.end><lb></lb>of the Heart and Lungs, being very far <lb></lb>from being Synchronical: Beſides, that <lb></lb>the Spirits ſeeming to be but the moſt <lb></lb>ſubtle and unctuous Particles of the <lb></lb>Blood, appear to be of a very differing <lb></lb>Nature from that of the lean and incom<lb></lb>buſtible Corpuſcles of Air. </s> <s>Other Ob<lb></lb>jections againſt this Opinion have been <lb></lb>propoſ'd, and preſt by that excellent Ana<lb></lb>tomiſt, and my Induſtrious Friend, Dr. <lb></lb><emph type="italics"></emph>Highmore,<emph.end type="italics"></emph.end> to whom I ſhall therefore refer <lb></lb>you. </s></p><p type="main"> <s>Another Opinion there is touching Re<lb></lb>ſpiration, which makes the genuine uſe of <lb></lb>it to be Ventilation (not of the Heart, <lb></lb>but) of the Blood, in its paſſage thorow <lb></lb>the Lungs; in which paſſage, it is diſ<lb></lb>burthened of thoſe Excrementitious <lb></lb>Steams, proceeding, for the moſt part, <lb></lb>from the ſuperfluous Seroſities of the <lb></lb>Blood, (we may adde) and of the <emph type="italics"></emph>Chyle<emph.end type="italics"></emph.end><lb></lb>too, which (by thoſe new Conduits of <lb></lb>late very happily detected by the famous <pb xlink:href="013/01/381.jpg" pagenum="351"></pb><emph type="italics"></emph>Pecquet<emph.end type="italics"></emph.end>) hath been newly mix'd with it in <lb></lb>the Heart.) And this Opinion is that of <lb></lb>the Induſtrious <emph type="italics"></emph>Mœbius,<emph.end type="italics"></emph.end> and is ſaid to <lb></lb>have been that of that excellent Philoſo<lb></lb>pher <emph type="italics"></emph>Gaſſendus;<emph.end type="italics"></emph.end> and hath been in part an <lb></lb>Opinion almoſt vulgar: But this <emph type="italics"></emph>Hypo<lb></lb>theſis<emph.end type="italics"></emph.end> may be explicated two ways: For <lb></lb>firſt, The neceſſity of the Air in Reſpi<lb></lb>ration, may be ſuppoſ'd to proceed from <lb></lb>hence; That as a Flame cannot long burn <lb></lb>in a narrow and cloſe place, becauſe the <lb></lb>Fuliginous Steams it unceſſantly throws <lb></lb>out, cannot be long receiv'd into the am<lb></lb>bient Body; which after a while growing <lb></lb>too full of them, to admit any more, ſti<lb></lb>fles the flame, ſo that the vital Fire in the <lb></lb>Heart requires an ambient Body, of a <lb></lb>yielding nature, to receive into it the ſu<lb></lb>perfluous Seroſities and other Recrements <lb></lb>of the Blood, whoſe ſeaſonable Expulſi<lb></lb>on is requiſite to depurate the Maſs of <lb></lb>Blood, and make it fit both to Circulate; <lb></lb>and to maintain the vital heat reſiding in <lb></lb>the Heart. </s> <s>The other way of explicating <lb></lb>the above-mention'd <emph type="italics"></emph>Hypotheſis,<emph.end type="italics"></emph.end> is, by <lb></lb>ſuppoſing, that the Air does not onely, as <lb></lb>a Receptacle, admit into its Pores the Ex<lb></lb>crementitious vapors of the Blood, when <lb></lb>they are expell'd through the Wind-Pipe, <pb xlink:href="013/01/382.jpg" pagenum="352"></pb>but does alſo convey them out of the <lb></lb>Lungs, in regard that the inſpired Air, <lb></lb>reaching to all the ends of the <emph type="italics"></emph>Aſpera Ar<lb></lb>teria,<emph.end type="italics"></emph.end> does there aſſociate it ſelf with the <lb></lb>Exhalations of the circulating Blood, and <lb></lb>when tis exploded, carrys them away with <lb></lb>it ſelf, as we ſee that winds ſpeedily dry up <lb></lb>the ſurfaces of wet Bodies, not to ſay any <lb></lb>thing of what we formerly obſervd touch<lb></lb>ing our Liquor, whoſe fumes were ſtrange<lb></lb>ly elevated upon the Ingreſs of the Air. </s></p><p type="main"> <s>Now of theſe two ways of explicating <lb></lb>the uſe of Reſpiration, our Engine af<lb></lb>fords us this Objection againſt the firſt; <lb></lb>That upon the Exſuction of the Air, the <lb></lb>Animals die a great deal ſooner then if it <lb></lb>were left in the Veſſel; though by that <lb></lb>Exſuction the ambient ſpace is left much <lb></lb>more free to receive the ſteams that are ei<lb></lb>ther breathed out of the Lungs of the <lb></lb>Animal, or diſcharg'd by inſenſible Tran<lb></lb>ſpiration through the Pores of his <lb></lb>Skin. </s></p><p type="main"> <s>But if the <emph type="italics"></emph>Hypotheſis<emph.end type="italics"></emph.end> propoſ'd, be taken <lb></lb>in the other ſenſe, it ſeems congruous e<lb></lb>nough to that grand obſervation, which <lb></lb>partly the <emph type="italics"></emph>Phænomena<emph.end type="italics"></emph.end> of our Engine, and <lb></lb>partly the relations of Travellers, have <lb></lb>ſuggeſted to us, namely, That there is a <pb xlink:href="013/01/383.jpg" pagenum="353"></pb>certain conſiſtence of Air requiſite to Re<lb></lb>ſpiration; ſo that if it be too thick, and <lb></lb>already over-charged with vapors, it will <lb></lb>be unfit to unite with, and carry off thoſe <lb></lb>of the Blood, as Water will diſſolve, and <lb></lb>aſſociate to it ſelf but a certain proportion <lb></lb>of ſaline Corpuſcles; and if it be too <lb></lb>thin or rarefied, the number or ſize of the <lb></lb>Aërial Particles is too ſmall to be able to <lb></lb>aſſume and carry off the halituous Excre<lb></lb>ments of the Blood, in ſuch plenty as is <lb></lb>requiſite. </s></p><p type="main"> <s>Now that Air too much thicken'd (and <lb></lb>as it were clogg'd) with Steams, is unfit <lb></lb>for Reſpiration, may appear by what is <lb></lb>wont to happen in the Lead-Mines of <emph type="italics"></emph>De<lb></lb>vonſhire,<emph.end type="italics"></emph.end> (and, for ought I know, in thoſe <lb></lb>too of other Countrys, though I have <lb></lb>ſeen Mines where no ſuch thing was com<lb></lb>plain'd of) for I have been inform'd by <lb></lb>more then one credible Perſon (and parti<lb></lb>cularly by an Ingenious Man, that has of<lb></lb>ten, for curioſity, digg'd in thoſe Mines, <lb></lb>and been imploy'd about them) that there <lb></lb>often riſes Damps, as retaining the <emph type="italics"></emph>Ger<lb></lb>mane<emph.end type="italics"></emph.end> Word by which they call them) <lb></lb>which does ſo thicken the Air, that unleſs <lb></lb>the Work-men ſpeedily make ſigns to <lb></lb>them that are above, they would (which <pb xlink:href="013/01/384.jpg" pagenum="354"></pb>alſo ſometimes happens) be preſently <lb></lb>ſtifled for want of Breath; and though <lb></lb>their Companions do make haſte to draw <lb></lb>them up, yet frequently, by that time <lb></lb>they come to the free Air, they are, as it <lb></lb>were, in a ſwoon, and are a good while be<lb></lb>fore they come to themſelves again. </s> <s>And <lb></lb>that this ſwooning ſeems not to proceed <lb></lb>from any Arſenical or Poyſonous Exhala<lb></lb>tion contain'd in the Damp, as from its <lb></lb>over-much condenſing the Air, ſeems pro<lb></lb>bable from hence; That the ſame Damps <lb></lb>oftentimes leiſurely extinguiſh the flames <lb></lb>of their Candles or Lamps; and from <lb></lb>hence alſo that it appears (by many Rela<lb></lb>tions of Authentical Authors) that in <lb></lb>thoſe Cellars where great ſtore of new <lb></lb>Wine is ſet to work, men have been ſuffo<lb></lb>cated by the too great plenty of the ſteams <lb></lb>exhaling from the Muſt, and too much <lb></lb>thickning the Air: as may be gathered <lb></lb>from the cuſtom that is now uſed in ſome <lb></lb>hot Countrys, where thoſe that have oc<lb></lb>caſion to go into ſuch Cellars, carry with <lb></lb>them a quantity of well kindled Coals, <lb></lb>which they hold near their Faces; where<lb></lb>by it comes to paſs, that the Fire diſcuſ<lb></lb>ſing the Fumes, and rarefying the Air re<lb></lb>duces the ambient Body to a conſiſtence fit <lb></lb>for Reſpiration.</s></p> <pb xlink:href="013/01/385.jpg" pagenum="355"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/386.jpg" pagenum="356"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/387.jpg" pagenum="357"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/388.jpg" pagenum="358"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/389.jpg" pagenum="359"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/390.jpg" pagenum="360"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/391.jpg" pagenum="361"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/392.jpg" pagenum="362"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/393.jpg" pagenum="363"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/394.jpg" pagenum="364"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/395.jpg" pagenum="365"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/396.jpg" pagenum="366"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/397.jpg" pagenum="367"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/398.jpg" pagenum="368"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/399.jpg" pagenum="369"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/400.jpg" pagenum="370"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/401.jpg" pagenum="371"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/402.jpg" pagenum="372"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/403.jpg" pagenum="373"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/404.jpg" pagenum="374"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/405.jpg" pagenum="375"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/406.jpg" pagenum="376"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/407.jpg" pagenum="377"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/408.jpg" pagenum="378"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/409.jpg" pagenum="379"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/410.jpg" pagenum="380"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/411.jpg" pagenum="381"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/412.jpg" pagenum="382"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/413.jpg" pagenum="383"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/414.jpg" pagenum="384"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/415.jpg" pagenum="385"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/416.jpg" pagenum="386"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/417.jpg" pagenum="387"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/418.jpg" pagenum="388"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/419.jpg" pagenum="389"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/420.jpg" pagenum="390"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/421.jpg" pagenum="391"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/422.jpg" pagenum="392"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/423.jpg" pagenum="393"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/424.jpg" pagenum="394"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/425.jpg" pagenum="395"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/426.jpg" pagenum="396"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/427.jpg" pagenum="397"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/428.jpg" pagenum="398"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/429.jpg" pagenum="399"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/430.jpg" pagenum="400"></pb><p><s>page not transcribed</s></p> <pb xlink:href="013/01/431.jpg" pagenum="401"></pb><p><s>page not transcribed</s></p> </chap> </body> <back></back> </text></archimedes>