<pb>
<C>NEW
<I>EXPERIMENTS
Phy$ico-Mechanicall
Touching the Air.</I></C>
<pb>
<C>NEW
EXPERIMENTS
<I>Phy$ico-Mechanicall,</I>
Touching</C>
<C>The SPRING of the AIR,
and its EFFECTS,
(Made, for the mo$t part, in a New
<I>PNEuMATICAL ENGINE</I>)</C>
<C>Written by way of LETTER</C>
<C>To the Right Honorable <I>Charles</I>
Lord Vicount of <I>Dungarvan,</I>
Elde$t Son to the EARL of <I>CORKE.</I></C>
<C>By the Honorable <I>Robert Boyle</I> E$q;</C>
<FIG>
<C><I>OXFORD:</I>
Printed by <I>H: Hall,</I> Printer to the Univer$ity,
for <I>The: Robin$on.</I> 1660.</C>
<pb>
<FIG>
<C>To the Reader.</C>
<p><I>ALthough the following Trea-
ti$e being far more prolix
then becomes a Letter, and
then I at fir$t intended it; I
am very unwilling to en-
crea$e the already exce$sive bulk of the
Book by a Preface, yet there are $ome par-
ticulars that I think my $elf oblig'd to take
notice of to the Reader, as things, that will
either concern him to know, or me to have
known.</I>
<p><I>In the fir$t place then: If it be demand-
ed why I publi$h to the World a Letter, which
by its Stile and diver$e Pa$$ages, appears
to have been written as well For, as To a
particular Per$on; I have chiefly the$e two
things to an$wer: The one, That the Ex-
periments therein related, having been ma-
ny of them try'd in the pre$ence of Ingeni-
ous Men; and by that means having made</I>
<pb>
<I>$ome noi$e among the</I> Virtuo$i (<I>in$omuch
that $ome of them have been $ent into Fo-
reign Countries, where they have had the
luck not to be de$pi$'d) I could not without
quite tyring more then one</I> Amanuen$is, <I>give
out half as many Copies of them as were $o
earne$tly de$ired, that I could not civilly
refu$e them. The other, That intelligent
Per$ons in matters of this kinde per$waded
me, that the publication of what I had ob-
$erv'd touching the Nature of the Air,
would not be u$ele$s to the World; and that
in an Age $o taken with Novelties as is ours,
the$e n<*>w Experiments would be grateful to
the Lovers of free and real Learning: So
that I might at once comply with my grand
De$ign of promoting Experimental and
U$eful Philo$ophy, and obtain the great $a-
tisfaction of giving $ome to ingenious Men;
the hope of which, is, I confe$s, a tempta-
tion that I cannot ca$ily re$i$t.</I>
<p><I>Of my being $omewhat prolix in many
of my Experiments, I have the$e Rea$ons
to render, That $ome of them being altoge-
ther new, $eem'd to need the being circum-
$tantially related, to keep the Reader from
di$tru$ting them: That divers Circum-
$tances I did here and there $et down for fear
of forgetting them, when I may hereafter</I>
<pb>
<I>have occa$ion to make u$e of them in my o-
ther Writings: That in divers ca$es I
thought it nece$$ary to deliver things cir-
cum$tantially, that the Per$on I addre$$ed
them to, might without mi$take, and with
as little trouble as is po$sible, be able to re-
peat $uch unu$ual Experiments: and that
after I con$ented to let my Ob$ervations be
made publick, the mo$t ordinary Rea$on of
my prolixity was, That fore$eeing that $uch
a trouble as I met with in making tho$e try-
als carefully, and the great expence of time
that they nece$$arily require, (not to mention
the charges of making the Engine, and im-
ploying a man to manage it) will probably
keep mo$t men from trying again the$e Ex-
periments; I thought I might doe the gene-
rality of my Readers no unacceptable pe<*>ce
of $ervice, by $o punctually relating what
I carefully ob$erv'd, that they may look up-
on the$e Narratives as $tanding Records in
our new Pneumaticks, and need not reite-
rate them$elves an Experiment to have as
di$tinct an Idea of it, as may $uffice them
to ground their Reflections and Speculations
upon.</I>
<p><I>And becau$e $ometimes 'tis the Di$cour$e
made upon the Experiment that makes it
appear prolix, I have commonly left a con-</I>
<pb>
<I>$picuous interval betwixt $uch Di$cour$es,
and the Experiments whereunto they belong,
or are annexed; that they who de$ire onely
the Hi$torical part of the account we give
of our Engine, may read the Narra-
tives, without being put to the trouble
of reading the Reflections too: Which I
here take notice of, for the $ake of tho$e
that are well ver$'d in the New Philo$ophy,
and in the Mathematicks; that $uch
may skip what was de$ign'd, but for $uch
Per$ons as may be le$s acquainted even then
I, with matters of this nature ($carce $o
much as mention'd by any Writer in our
Language) and not for them from whom
I $hall be much more forward to learn, then
to pretend to teach them. Of my being
wont to $peak rather doubtfully, or he$itant-
ly, then re$olvedly, concerning matters
wherein I apprehend $ome difficulty, I have
in another Treati$e (which may, through
Gods A$si$tance, come abroad ere long)
given a particular, and I hope a $atisfacto-
ry account: Wherefore I $hall now defend
my Practice but by the Ob$ervation of</I> Ari-
$totle, <I>who $omewhere notes, That to $eem
to know all things certainly, and to $peak
po$itively of them, is a trick of bold and
yong Fellows: Whereas tho$e that are in-</I>
<pb>
<I>deed intelligent and con$iderate, are wont to
imploy more wary and diffident Expre$si-
ons, or (as he $peaks)</I> <G><*>sife/ad<*> a)ei\ to\ <*>s,
<*> to\ ta\xa</G>.
<p><I>There are divers Reflections, and other
Pa$$ages in the following Epi$tle, and even
$ome Experiments (occa$ionally mention'd)
which may $eem either impertinent or $u-
perfluous, but are not $o: Being purpo$ely
written, either to evince $ome truth oppo$'d,
or di$prove $ome erroneous conceit main-
tain'd, by $ome eminent New Philo$opher,
or by $ome other Ingenious Men, who, I
pre$um'd, would ea$ily forgive me the ha-
ving on $uch occa$ions purpo$ely omitted
their Names; though an inqui$itive Per$on
will probably di$cover divers of them, by
the mention of the Opinions di$prov'd in
the Experiments I am excu$ing.</I>
<p><I>Ever $ince I di$cern'd the u$efulne$s
of $peculative Geometry to Natural Phi-
lo$ophy, the unhappy Di$tempers of my Eyes,
have $o far kept me from being much con-
ver$ant in it, that I fear I $hall need the par-
do<*> of my Mathematical Readers, for $ome
Pa$$ages, which if I had been deeply skill'd
in Geometry, I $hould have treated more ac-
curately.</I>
<pb>
<p><I>And indeed, having, for Rea$ons el$e-
where deduc'd, purpo$ely kept my $elf a
$tranger to mo$t of the new</I> Hypothe$es <I>in
Philo$ophy, I am $en$ible enough that the
Engine I treat of has prevail'd with me to
write of $ome $ubjects which are $ufficient-
ly remote from tho$e I have been mo$t con-
ver$ant in. And having been reduc'd to
write the greate$t part of the en$uing Letter
at a di$tance, not onely from my Library,
but from my own Manu$cripts, I cannot
but fear that my Di$cour$es do not onely
want many choice things wherewith the
Learned Writings of others might have en-
riched or imbelli$hed them: But that partly
for this Rea$on, and partly for that touch'd
upon a little before, It is po$sible I may
have mention'd $ome Notions already pub-
li$h'd by others, without taking notice of the
Authors, not out of any de$ign to defraud
de$erving Men, but for want of knowing
$uch particulars to have been already pub-
li$h'd by them: E$pecially the Experiments
of our Engine being them$elves $ufficient
to hint $uch Notions as we build upon
them.</I>
<p><I>The order of the Experiments every
Reader may alter, as $uits be$t with his own
De$ign in peru$ing them; For not onely all</I>
<pb>
<I>tho$e betwixt whom there is an Affinity in
Nature (by belonging to one $ubject) are not
always plac'd one by another, but they are
not $till $et down $o much as in the order
wherein they were made; but mo$t common-
ly in that ca$ual one wherein my occa$ions in-
duc'd me to di$patch them to the Pre$s. And,
which is wor$e, I did u$ually $end quite a-
way the former Experiments, before the
later were written, or perhaps $o much as
made: Whereby I lo$t the advantage of cor-
recting and $upplying the Imperfections of
what I had formerly written, by the light of
my $ub$equent Tryals and Di$coveries.</I>
<p><I>Be$ides all this, the di$temper in my eyes
forbidding me not onely to write my $elf $o
much as one Experiment, but even to read
over my $elf what I dictated to others. I can-
not but fear, that be$ides the Authors mi$takes,
this Edition may be blemi$h'd by many, that
may be properly imputed to a very unskil-
ful Writer (whom I was often times by ha$te
reduc'd again$t my cu$tom to imploy) and
may have e$caped the Diligence of that
Learned Friend, that does me the favor to
over-$ee the Pre$s; e$pecially there being
the di$tance of two days Fourney betwixt it
and me.</I>
<p><I>I need not perhaps repre$ent to the equi-</I>
<pb>
<I>table Reader, how much the $trange Confu-
$ions of this unhappy Nation, in the mid$t
of which I have made and written the$e
Experiments, are apt to di$turb that calm-
ne$s of Minde, and undi$tractednc$s of
Thoughts, that are wont to be requi$ite to
Happy Speculations. But I pre$ume,
that by all the$e things put together, he
will readily perceive, That I have been
$o far from following the Poets prudent
Coun$el touching the $low Publication of
Books de$ign'd to purcha$e credit by,</I>
<p>&mdash;&mdash; Nonumque prematur in Annum
<p><I>that I $uffer this Treati$e to come abroad
into the World with a multitude of Di$ad-
vantages.</I>
<p><I>But if it be demanded, why then I did
not make it f<*>ter for the Pre$s before I $ent
it thither? my An$wer mu$t be, That not
at fir$t imagining that this $ort of Experi-
ments would prove any thing near $o trouble-
$ome, either to make, or to Record, as I
afterwards found them, I did, to engage
the Printer to di$patch, promi$e him to $end
him the whole Epi$tle in a very $hort time:
So that although now and then the occa$ional
vacations of the Pre$s, by rea$on of Fe$ti-</I>
<pb>
<I>vals, or the ab$ence of the Corrector, gave
me the lei$ure to ex$paciate upon $ome $ub-
ject; yet being oftentimes call'd upon to di$-
patch the Papers to the Pre$s, my promi$e,
and many unexpected Avocations, obliged
me to a ha$te, which, though it have detract-
ed nothing from the Faithfulne$s of the
Hi$torical part of our Book, has (I fear)
been di$advantageous enough to all the re$t.
And I made the le$s $cruple to let the fol-
lowing Papers pa$s out of my hands, with
all their Imperfections; becau$e, as the
publick Affairs, and my own, were then
circum$tanc'd, I knew not when (if at all)
I $hould be again in a condition to pro$ecute
Experiments of this kinde; e$pecially,
$ince (to omit my being almo$t weary of be-
ing, as it were, confin'd to one $ort of Ex-
periments) I am pre-ingag'd (if it plea$e
God to vouch$afe me Life and Health) to
imploy my fir$t lei$ure in the publication of
$ome other Phy$iological Papers, which I
thought 'twould make me much the $itter to
take in hand, if I fir$t di$patch'd all that
I had at this time to write touching our
Engine.</I>
<p><I>I have this further to adde, by way
of Excu$e, That as it has been my de$ign
in publi$hing the$e Experiments to gratifie</I>
<pb>
<I>Ingenious men; $o, if I have not been
much flattered, I may hope that the vari-
ous hints to be met with in the following
Letter, will (at lea$t) $omewhat awaken
mens thoughts, &amp; excite them to new $pecula-
tions ($uch as perhaps even inqui$itive men
would $carce el$e light upon) and I need not
de$pair, that even the examination of $uch
new Su$picions and Enquiries will hence al-
$o, at lea$t Occa$ionally be facilitated: I
$aid Occa$ionally, becau$e it being, as 'tis
proverbially $aid,</I> Facile Inventis addere.
<I>It $eems not irrational to expect, that our
Engine it $elf, and divers of our Experi-
ments, will be much promoted by the Indu-
$try of Inventive and Mathematical Wits,
who$e contrivances may ea$ily either correct
or $upply, and con$equently $urpa$s many of
tho$e we have made u$e of. And, particu-
larly, if Men by skill and patience can ar-
rive both to evacuate $uch Receivers as
ours, till there be no more Air left in them,
then there $eems to have remain'd in the
Gla$$es made u$e of about the Magdebur-
gick Experiment (hereafter to be mention-
ed) and to keep out the Air for a competent
while, the U$efulne$s and Di$coveries of our
Engine, will not be a little advanc'd. And
perhaps that may belong to it, which I re-</I>
<pb>
<I>member</I> Seneca <I>$peaks of Nature,</I> Initia-
tos (<I>$ays be</I>) nos credimus, in Ve$tibulo
ejus h&aelig;remus: <I>For being now in a place
where we are not quite de$titute of moderate-
ly skilful Artificers, we have, $ince the
Conclu$ion of the following Letter, made
$ome Additions to our Engine, by who$e help
we finde (upon $ome new tryals) that we
may be able, without much of new trouble,
to keep the ambient Air out of the exhau-
$ted Receiver for a whole day; and perhaps
we $hould be able to keep it out much longer,
if before we $hall have di$patch'd $ome ur-
gent Affairs, and publi$h'd $ome Papers for
which a kinde of Promi$e is thought to make
us Debtors to the Pre$s, we could be at lei-
$ure to pro$ecute $uch Experiments, as may
po$sibly afford a Supplement to the follow-
ing Treati$e, from which I $hall now no lon-
ger detain the Reader.</I>
<p><I>I know</I>
<pb>
<FIG>
<p>Friendly Reader,
<p><I>I Know all Per$ons
that have a publick
Spirit for the Ad-
vancement of Lear-
ning, will think much that this
piece came not out in a Lan-
guage of more general U$e,
then this you $ee it now attir'd
in; e$pecially $ince the Excel-
lent Noble Per$on, who is the
Author, is known to be well a-
ble him$elf (being almo$t uni-
ver$ally a Lingui$t) to have gi-
ven it either the Old Latin, or</I>
<pb>
<I>the newer French Dre$s.</I>
<p><I>But if it be an Honor to a
Language to be preferr'd, and
this Honor breeds $ometimes an
Emulation, as anciently it did
between the</I> Greeks <I>and</I> Ro-
mans, <I>it cannot be thought
unhand$ome for an Engli$h
Nobleman to have preferr'd
his own: And it may be a $uf-
ficient Rea$on for the Gentry
of Forein Parts to learn our
Speech, or keep Interpreters,
that they are $ure to have for
their requital, from many of
our Engli$h Writers (as here
from this piece) much curiou$ly
ingenious, and profitable Lear-
ning.</I>
<pb>
<p><I>But as to this particular (give
me leave to u$e Words from a
Story)</I> Since the Mountain
cannot come to <I>Mahomet,
Mahomet</I> will go to the
Mountain<I>: I mean thus;
Becau$e many witty Men, Per-
$ons of Honor and E$tate e$pe-
cially, may be $uppo$'d to be a-
ble to make a better account, by
employing their Studies and
Time on Matter then Words,
and $o are ju$tly impeded from
learning Languages; And be-
cau$e (as I may judge) the no-
ble Author is willing to oblige all
Men, He has already provi-
ded, that this piece $hall $hort-
ly be done into Latine, that $o</I>
<pb>
<I>it may come home to divers wor-
thy Per$ons in its Stream, who
cannot travel to finde it out in
its fir$t Origine.</I>
<p><I>Having therefore leave $o
to do, I cannot forbear to give
the World the Adverti$ement
of this Latine Edition, le$t
$ome skilful Arti$t $hould take
needle$s pains about a Work,
which will, ere long (by Gods
furtherance) be done to his
Hands; For $uch unprofitable
expences of Study have too fre-
quently happened, and too much
to the di$advantage of Learn-
ing, for want of a $ufficient
Corre$pondence and Intercour$e
between $uch as are exerci$ed</I>
<pb>
<I>in the Mines of Wi$dome.</I>
<p><I>This is all the trouble I $hall
at pre$ent give you: Nor $hall I
need minde thee, if you have a
true gu$t for the Book you read,
to have an honor and thankful
regard to the Per$on that has
favor'd us with the Communi-
cation of the$e his Tryals, &amp; is
manife$tly $o great a Patron
and Friend to Experimental
Learning, and all true Wi$dom;
for $hould you fail in this, you
might de$ervedly be depriv'd of
$ome other Ob$ervations on the
$ame $ubject, which the Au-
thor, I heare, has made $ince the
fini$hing of this Treati$e.</I>
<p><I>I de$ire to be excu$ed that I</I>
<pb>
<I>not make Excu$es for the $low-
ne$s of the Publication, hoping
that the long expectation you
have had of it, will enhance, and
not dimini$h your delight in the
enjoyment of a piece like to be,
among$t the $tudents in accurate
Philo$ophy, of $o generall accep-
tance. Farewel.</I>
<p>R: Sh.
<FIG>
<pb>
<FIG>
<C>A Summary of the chief Matters treated
of in this Epi$tolical Di$cour$e.</C>
<p><I>THe</I> Pro&aelig;mium, <I>wherein is $et down the
occa$ion of this Di$cour$e,</I> 1. <I>The mo-
tives that induc'd the Author thereunto,</I> 2 &amp;c.
<I>The hints he received,</I> 5. <I>The things where-
in this Engine excels any that have yet been
made u$e of,</I> 6 &amp;c. <I>The de$cription of the
Engine and its parts,</I> 8 &amp;c. <I>The way of pre-
paring and u$ing it,</I> 15 &amp;c. <I>The divi$ion of
the Experiments tryable thereby into two
$orts, and the difficulty of excluding the
Air.</I> 18 &amp;c.
<p><I>The fir$t Experiment, touching the man-
ner of pumping out the Air, and by what de-
grees the Receiver is emptyed,</I> 20, &amp;c. <I>A di-
gre$sion touching the Spring or Ela$tical
power of the Air, with an attempt for a Me-
chanical Explication thereof, nece$$ary to be
premi$'d for the explanation of the</I> Ph&aelig;no-
mena, <I>exhibited in this and the $ub$equent
Experiments.</I> 22 &amp;c.
<p><I>The $econd Experiment, touching the pre$-
$ure of the Air again$t the $ides of the Bodies
it invirons,</I> 37 &amp;c. <I>with a digre$sive Ex-
plication of the pre$$ure of the Air included
within an ambient Body.</I> 39 &amp;c.
<pb>
<p><I>The third Experiment, touching the
force requi$ite to draw down the Sucker,</I> 42
&amp;c. <I>The Opinion of an eminent Modern
Naturali$t examin'd.</I> 44 &amp;c.
<p><I>The fourth Experiment, touching the
$welling of a Bladder; with the degrees by
which it increa$es,</I> 45 &amp;c. <I>Another Opini-
on of a Learned Author examin'd.</I> 48 &amp;c.
<p><I>The fifth Experiment, touching the break-
ing of a Bladder in the Receiver,</I> 49 &amp;c.
<I>And of another by heat.</I> 52
<p><I>The $ixth Experiment, of divers ways by
which the ela$tical expan$ion of the Air
was mea$ur'd.</I> 52 &amp;c
<p><I>The $eventh Experiment, touching what
Figure does be$t re$i$t the pre$$ure of the Air.</I> 62 &amp;c.
<p><I>The eighth Experiment, tending to a fur-
ther Demon$tration of the former, from the
breaking of gla$s a Helmet inward.</I> 64 &amp;c.
<p><I>The ninth Experiment, contains a fur-
ther confirmation from the breaking of a
Gla$s outward,</I> 66 &amp;c. <I>with an Experiment to
prove, that the$e</I> Ph&aelig;nomena <I>proceed not
from an invincible</I> Fuga vacui 69. <I>A de-
$cription of other $mall Receivers, and their
Conveniencies,</I> 70 &amp;c. <I>A Receipt for the
making of a Compo$ition to Cement crackt
Gla$$es.</I> 73
<pb>
<p><I>The tenth Experiment, touching the fla-
ming of Candles inclo$ed in the Receiver.</I> 74 &amp;c.
<p><I>The eleventh Expertment, touching the
burning of Coals,</I> 78. <I>And the la$ting of
the excande$cence of an included piece of I-
ron.</I> 80.
<p><I>The twelfth Experiment concerning the
burning of Match.</I> 82
<p><I>The thirteenth Experiment, concerning
the further pro$ecution of the preceding,
tending to prove the extinction of the Fire
in the former Experiments, not to have
proceeded from the pre$$ure of the Fire by the
Fumes,</I> 84. <I>Some remarkable Circum$tan-
ces of it,</I> 86. <I>The Experiment of Match
try'd in a $mall Receiver.</I> 87
<p><I>The fourteenth Experiment, touching the
$triking Fire, and kindling of Powder with
the Lock of a Pi$tol in the evacuated Recei-
ver.</I> 88 &amp;c.
<p><I>The fifteenth Experiment, touching the
un$ucce$sfulne$s of kindling included Bo-
dies with a burning Gla$s, and the Au-
thors intention to pro$ecute it further.</I> 102
<p><I>The $ixteenth Experiment, concerning the
operation of the Load$tone.</I> 105, &amp;c.
<pb>
<p><I>The $eventeenth Experiment, touching the
gradual de$cent of the Quick-$ilver in the
Torricellian Experiment,</I> 106 &amp;c. <I>Some
ob$ervable Circum$tances concerning it,</I>
112 &amp;c. <I>The $ame Experiment try'd in
one of the $mall Receivers,</I> 115. <I>How
this Experiment may be made u$e of to know
the $trength of the pre$$ure of the Air for
every degree of Rarefaction,</I> 116 &amp;c. <I>The
tryal of the $ame Experiment in a Tube not
two foot long,</I> 118. <I>The rai$ing of the Mer-
curial Cylinder, by the forcing of more Air
into the Receiver,</I> 119. <I>Some Allegations
for and again$t a</I> Vacuum <I>con$ider'd,</I> 120
&amp;c. <I>Some Adverti$ements concerning the
inconveniencies that may ari$e from the di-
ver$ity of mea$ures made u$e of for the defi-
ning the Altitute of the Mercurial Cylinder;
and from the neglect of little parcels of Air
apt to remain between the Mercury and the
concave $urface of the Tube,</I> 123 &amp;c. <I>Some
Expedients for the more exact filling the
Tube,</I> 127. <I>The height the Author once found
of the Mercurial Cylinder, according to En-
gli$h mea$ure.</I> 128.
<p><I>The eighteenth Experiment, containing
a new Ob$ervation touching the variation
of the height of the Mercurial Cylinder in
the $ame Tube, with an o$$er at the rea$on</I>
<pb>
<I>thereof.</I> 129 &amp;c.
<p><I>The</I> 19<SUP>th</SUP> <I>Experiment, touching the $ub-
$iding of a Cylinder of Water,</I> 140 &amp;c. <I>The
$ame try'd in a $mall Receiver.</I> 143
<p><I>The</I> 20<SUP>th</SUP> <I>Experiment, touching the</I> Ela-
ter <I>of Water, with a digre$sive Experiment
to the $ame purpo$e</I> 144 &amp;c.
<p><I>The</I> 21 <I>Experiment, being a pro$ecution
of the former Enquiry, by Experimenting
the Generation of Bubbles under Water, a
recital of $ome notable Circum$tances, with
$ome ob$ervable Corollary's deduc'd there-
from.</I> 147 &amp;c.
<p><I>The</I> 22<SUP>d</SUP> <I>Experiment, tending to a deter-
mination of the Enquiry propo$'d in the for-
mer Experiment, by proving the matter of
the$e Bubbles from their permanency to be
Air: The Experiments try'd in the great
and $mall Receivers, evincing the $ame
thing,</I> 155 &amp;c. <I>An Experiment wherein
there appear'd Bubbles in Quick-$ilver,</I>
160. <I>The Authors Inference,</I> 162. <I>A di-
gre$sive Enquiry, whether or no Air may be
generated anew; with $everal Hi$tories and
Experiments, tending to the re$olving and
clearing thereof.</I> 162 &amp;c <I>The Authors ex-
cu$e for $o long a Digre$sion.</I> 181
<p><I>The</I> 23<SUP>d</SUP> <I>Experiment, containing a fur-
ther Enquiry touching Bubbles mad with</I>
<pb>
<I>common and di$till'd Water.</I> 182
<p><I>The</I> 24<SUP>th</SUP> <I>Experiment, wherein the inqui-
ry is pro$ecuted with other Liquors, as with
Sallet Oyl, Oyl of Turpentine, a Solution of
Tartar, Spirit of Vinegar, Red-wine, Milk,
Hen's Eggs, Spirit of Urine, Spirit of
Wine and Water, Spirit of Wine.</I> 187 &amp;c.
<I>The wonderful expan$ion of the Spirit of
Wine.</I> 194
<p><I>The</I> 25<SUP>th</SUP> <I>Experiment, touching the ex-
pan$ion and gravity of the Air under wa-
ter.</I> 195 &amp;c.
<p><I>The</I> 26<SUP>th</SUP> <I>Experiment, touching the Vi-
brations of a</I> Pendulum. 202 &amp;c.
<p><I>The</I> 27<SUP>th</SUP> <I>Experiment, touching the pro-
pagation of $ound: And the Authors inten-
tion of trying $ome other Experiments, for
the further elucidation thereof.</I> 210 &amp;c.
<p><I>The</I> 28 <I>Experiment, touching the $udden
cruption of Bubbles from the water, when
the airs pre$$ure was $peedily remov'd.</I> 214
<p><I>The</I> 29 <I>Experiment, touching the cau$e
of the a$cent of Fumes and Vapors, wherein
'tis prov'd (from the $everal motions, which
the Fumes of a $trange $moaking Liquor, of
the Authors, were ob$erv'd to have in the Re-
ceiver, upon the ex$uction of the Air) that
the rea$on of their a$cent proceeds from the
gravity of the ambient air, and not from any
po$itive levity of their own.</I> 217 &amp;c.
<pb>
<p><I>The</I> 30 <I>Experiment, concerning the na-
ture of a fluid Body, illu$trated by the exam-
ple of $moak which in $everal circum$tances
$eems very much to re$emble the property of a
fluid Body,</I> 224 &amp;c. <I>A conjecture of the
cau$e of the Suns undulation.</I> 228
<p><I>The</I> 31 <I>Experiment, concerning the</I> Ph&aelig;-
nomena <I>of two flat Marbles exactly plain'd
and wrought together, and the true rea$on
thereof,</I> 229. <I>The Authors intention for the
further pro$ecution thereof, &amp; what hindred
him; the rea$on why the under Marble did
not fal from the upper (being onely conjoynd
with Spirit of Wine) when the Receiver was
evacuated. And a notable relation concern-
ing the cohe$ion of flat Bodies.</I> 231 &amp;c.
<p><I>The</I> 32 <I>Experiment, touching the forcible
pre$$ure of the Air again$t the outward $u-
perficies of a Valve, fa$ten'd upon the $top-
cock of the Receiver. The Diameter of it,
and the weight it $u$tain'd.</I> 233 &amp;c.
<p><I>The</I> 33 <I>experiment, touching the great pre$-
$ure of the Air again$t the under $uperficies
of the Sucker,</I> 236 &amp;c. <I>what weight was re-
qui$ite to depre$s it, &amp; what weight it would
lift and carry up with it,</I> 239 &amp;c. <I>what im-
provement &amp; u$e there may be made of this
experiment,</I> 242. <I>A Di$cour$e touching the
nature of Suction, proving that</I> fuga vacui
<I>is not the adequate cau$e thereof.</I> 243 &amp;c.
<pb>
<p><I>The</I> 34<SUP>th</SUP> <I>Experiment, containing $everal
attempts for the weighing of light Bodies in
the exhau$ted Receiver.</I> 258 &amp;c.
<p><I>The</I> 35<SUP>th</SUP> <I>Experiment, touching the cau$e
of Filtration, and the ri$ing of Water in</I>
Siphons, 262 &amp;c. <I>A relation of a new
kinde of</I> Siphon, <I>of the Authors, upon
the occa$ion of trying the Experiment
lately ob$erv'd by $ome French-men, and fur-
ther improv'd by him$elf; and $ome conje-
ctures touching the cau$e of the exhibited</I>
Ph&aelig;nomena. 267 &amp;c.
<p><I>The</I> 36<SUP>th</SUP> <I>Experiment, touching the weigh-
ing of a parcel of Air in the exhau$ted Ve$-
$el; and $ome other Ob$ervations for the ex-
plication thereof,</I> 272 &amp;c. <I>An accidental
Experiment, tending to the further confir-
mation of the Authors Reflections upon the
fir$t Experiment; with a digre$sive Ob$er-
vation, noting the $ubtil penetrancy of $ome
Spirits, to exceed by far that of the Air,</I> 275
&amp;c. <I>And $ome other Experiments to $hew the
difficulty of the ingre$s of the Air into the
pores or holes of $ome bodies into which Wa-
ter will readily in$inuate it $elf,</I> 279 &amp;c. <I>with
a conjecture at the cau$e thereof,</I> 282. <I>The
Author returns to the pro$ecution if the in-
quiry after the gravity of the Air: But fir$t,
(upon the occa$ion of the tenacity of a thin</I>
<pb>
<I>Bubble of Gla$s) $ets down his thoughts con-
cerning the $trange exuperancy of $trength
in Air, agitated by heat, above what the
$ame has unagitated,</I> 283 &amp;c. <I>And then pro-
ceeds to the examination of the weight of the
Air by an</I> &AElig;olipile, <I>and compares the re$ult
thereof, with that of</I> Mer$ennus, 286. <I>The
Opinions and Experiments of divers Au-
thors, and $ome of his own, touching the
proportion of weight betwixt Water and Air,
are compar'd and examin'd by the Author,</I>
288. <I>The re$ult thereof,</I> 290. Mer$ennus
<I>his ob$ervation reconcil'd, with that of the
Author; and the proportion between the gra-
vity of Water and Air about</I> London, 291
&amp;c. <I>After the recital of the Opinions of $e-
veral Writers, touching the proportion of
gravity between Water and Quick-$ilver,
the Author $ets down his own tryals, made
$everal ways, together with his conclu$ion
therefrom,</I> 293 &amp;c. <I>The u$e he makes of this
inquiry for the ghe$sing at the height of the
Atmo$phere,</I> 297. <I>What other Experiments
are requi$ite to the determination thereof.</I>
299 &amp;c.
<p><I>The</I> 37<SUP>th</SUP> E<I>xperiment, touching the $trange
and odde</I> Ph&aelig;nomenon, <I>of the $udden fla$h-
es of light in the cavity of the Receiver; the
$everal circum$tances and difficulties of it,</I>
<pb>
<I>with $ome attempts towards the rendering at rea$on
thereof,</I> 301, &amp;c. <I>The Difficulty of $o doing fnr-
ther $hewn from the con$ideration of the various
changes of Air which doe not immediatly fall un-
der our $en$es,</I> 315. <I>this la$t propo$ition prou'd
by $everall ob$ervations.</I> 316.
<p><I>The</I> 38. <I>Experiment, touching the freezing of
water,</I> 319. &amp;c. <I>Aproblem, (concerning the great
force wherewith a freezing Liquor extends its $<*>lfe,)
propo$'d upon the Con$ideration of divers admirable
effects wrought thereby.</I> 320 &amp;c.
<p><I>The</I> 39. <I>Experiment, containing an inqui$ition
after the temperature of the $ub$tance that remain'd
in the cavity of the Receiver, after the Air was well
exhau$ted. The relation of a</I> Ph&aelig;nomenon, <I>$eeming
to proceed from the $welling of the Gla$s. With an
adverti$ement concerning the pliablene$s of Gla$s in
$mall peices.</I> 322. &amp;c.
<p><I>The</I> 40. <I>Experiment, touching the difficulty that
occur'd in making tryall whether rarified Air
were able to $u$taine flying in$ects.</I> 326. &amp;c
<p><I>The</I> 41. <I>Experiment, Exhibiting $everall try-
alls touching the re$piration of divers $orts of ani-
malls included in the Receiver,</I> 328, &amp;c. <I>With a
digre$$ion containing $ome doubts touching re$pira-
tion wherein are delivered $everall Experiments re-
lating thereunto.</I> 335 &amp;c.
<p><I>The</I> 42. <I>Experiment, touching the differing o-
peration of corro$ive Liquors in the emptied Receiver
and in the open Air.</I> 384
<p><I>The</I> 43. <I>Experiment, touching the $pontaneous E-
bullition of warm Liquors in the exhau$ted Receiver.</I> 388
<p><I>The Conclu$ion.</I> 394
<pb>
<FIG>
<pb>
<FIG>
<pb>
<FIG>
<pb>
<FIG>
<pb n=1>
<FIG>
<C>TO THE
LORD
OF
<I>DUNGARVAN,</I>
My Honoured and Dear
NEPHEW.</C>
<p><I>My Dear Lord,</I>
<p>REceiving in your la$t from
<I>Paris,</I> a de$ire that I would
adde $ome more Experi-
ments to tho$e I formerly
$ent You over: I could not
be $o much your Servant as I am, without
looking upon that De$ire as a Com-
mand; and con$equently, without think-
ing my $elf obliged to con$ider by what
$ort of Experiments it might the mo$t ac-
ceptably be obey'd. And at the $ame
<pb n=2>
time, perceiving by Letters from $ome
other Ingenious Per$ons at <I>Paris,</I> that $e-
veral of the <I>Virtuo$i</I> there, were very
intent upon the examination of the Inte-
re$t of the Ayr, in hindring the de$cent
of the Quick-$ilver, in the famous Expe-
riment touching a <I>Vacuum:</I> I thought I
could not comply with your De$ires in a
more fit and $ea$onable manner, then by
pro$ecuting and endeavoring to promote
that noble Experiment of <I>Torricell<*>s:</I>
and by pre$enting your Lord$hip an ac-
count of my attempts to illu$trate a $ub-
ject, about which, it's being $o much di$-
cour$'d of where you are, together with
your inbred Curio$ity, and love of Ex-
perimental Learning, made me $uppo$e
you $ufficiently inqui$itive.
<p>And though I pretend not to acquaint
you, on this occa$ion, with any $tore of
new Di$coveries yet po$$ibly I $hall be $o
happy, as to a$$i$t you to <I>know</I> $omethings
which you did formerly but <I>$uppo$e;</I> and
$hall pre$ent you, if not with new Theo-
ries, at lea$t with new <I>Proofs</I> of $uch as
are not yet become unque$tionable. And
if what I $hall deliver, have the good for-
tune to encourage and a$$i$t you to pro$e-
cute the Hints it will afford, I $hall ac-
<pb n=3>
count my $elf, in paying of a duty to
you, to have done a piece of Service to
the Commonwealth of Learning. Since
it may highly conduce to the advance-
ment of that Experimental Philo$ophy,
the effectual pur$uit of which, requires
as well a Pur$e as a <*>in, to endeere it
to <I>hopeful</I> Per$ons of your Quality: who
may accompli$h many things which o-
thers can but <I>wi$h</I> or, at mo$t, but <I>de$ign,</I>
by being able to imploy the Pre$ents of
Fortune in the $earch of the My$teries of
Nature.
<p>And I am not faintly induc'd to make
choice of this Subject, rather then any
of the expected Chymical ones, to enter-
tain your Lord$hip upon, by the$e two
Con$iderations: The one, That the Ayr
being $o nece$$ary to humane Life, that
not onely the generality of Men, but
mo$t other Creatures that breath, can-
not live many <I>minutes</I> without it; any
con$iderable di$covery of its Nature,
$eems likely to prove of moment to
Man-kinde. And the other is, That the
Ambient Ayr, being that whereto both
our own Bodies, and mo$t of the others
we deal with here below, are almo$t per-
petually contiguous; not onely its alte-
<pb n=4>
rations have a notable and manife$t $hare
in tho$e obvious effects, that men have
already been invited to a$cribe thereunto
$uch as are the various di$tempers inci-
dent to humane Bodies, e$pecially if cra-
zy, in the Spring, the Autumn, and al$o
on mo$t of the great and $udden changes
of Weather) but likewi$e, that the fur-
ther di$covery of the nature of the Ayr,
will probably di$cover to us, that it con-
curs more or le$s to the exhibiting of ma-
ny <I>Ph&aelig;nomena,</I> in which it hath hither-
to $carce been $u$pected to have any inte-
re$t. So that a True Account of any
Experiment that is New concerning a
thing, wherewith we have $uch con$tant
and nece$$ary intercour$e, may not one-
ly prove of $ome advantage to humane
Life, but gratifie Philo$ophers, by pro-
moting their Speculations on a Subject
which hath $o much opportunity to $olli-
cite their Curio$ity.
<p>And I $hould immediately proceed to
the mention of my Experiments, but that
I like too well that worthy $aying of the
Naturali$t <I>Pliny, Benignum e$t</I>
<MARG><I>In <*>.
lib.</I> 1.</MARG>
<I>&amp; plenum ingenui pudor is, fateri
per quos profeceris,</I> not to con-
form to it, by acquainting your Lord-
<pb n=5>
$hip, in the fir$t place, with the Hint I
had of the Engine I am to entertain you
of. You may be plea$'d to remember,
that a while before our $eparation in <I>Eng-
land,</I> I told you of a Book that I had
heard of, but not peru$'d, publi$h'd by
the indu$trious Je$uit <I>Schottus,</I> wherein
'twas $aid, He related how that ingenious
Gentleman <I>Otto Gericke,</I> Con$ul of <I>Mag-
deburg,</I> had lately practiced in <I>Germany</I> a
way of emptying Gla$s Ve$$els, by $uck-
ing out the Ayr at the mouth of the Ve$-
$el, plung'd under water: And you may
al$o perhaps remember, that I expre$$'d
my $elf much delighted with this Expe-
riment, $ince thereby the great force of
the external Air (either ru$hing in at the
open'd Orifice of the empty'd Ve$$el, or
violently forcing up the Water into it)
was rendred more obvious and con$picu-
ous, than in any Experiment that I had
formerly $een. And though it may appear
by $ome of tho$e Writings I $ometimes
fhew'd your Lord$hip, that I had been $ol-
licitous to try things upon the $ame
ground; yet in regard this Gentleman
was before-hand with me in producing
$uch con$iderable effects, by means of the
ex$uction of Air, I think my $elf oblig'd
<pb n=6>
to acknowledge the A$$i$tance, and En-
couragement the Report of his perfor-
mances hath afforded me.
<p>But as few inventions happen to be at
fir$t $o compleat, as not to be either ble-
mi$hd with $ome deficiencies needful to be
remedy'd, or otherwi$e capable of im-
provement: $o when the Engine we
have been $peaking of, comes to be more
attentively con$ider'd, there will appear
two very con$iderable things to be de-
$ir'd in it. For fir$t, the <I>Wind-Pump</I> (as
$ome body not improperly calls it) is $o
contriv'd, that to evacuate the Ve$$el
there is requir'd the continual labor of
two $trong men for divers hours. And
next (which is an imperfection of much
greater moment) the Receiver, or Gla$s
to be empty'd, con$i$ting of one entire
and uninterrupted Globe and Neck of
Gla$s; the whole Engine is $o made, that
things cannot be convey'd into it, where-
on to try Experiments: So that there
$eems but little (if any thing) more to be
expected from it, then tho$e very few
<I>Ph&aelig;nomena</I> that have been already ob-
$erv'd by the Author, and Recorded by
<I>Schottus.</I> Wherefore to remedy the$e
Inconveniences, I put both Mr. <I>G.</I>
<pb n=7>
and <I>R. Hook</I> (who hath al$o the Honor to
be known to your Lord$hip, and was with
me when I had the$e things under con$i-
deration) to contrive $ome Air Pump,
that might not, like the other, need to
be kept under water (which on divers oc-
ca$ions is inconvenient) &amp; might be more
ea$ily manag'd: And after an un$ucce$sful
try all or two of ways propo$'d by o-
thers, the la$t nam'd Per$on fitted me
with a Pump, anon to be de$crib'd. And
thus the fir$t Imperfection of the <I>German</I>
Engine, was in good mea$ure, though
not perfectly, remedy'd: And to $upply
the $econd de$ect, it was con$idered that
it would not perhaps prove impo$$ible to
leave in the Gla$s to be empty'd, a hole
large enough to put in a Mans Arm
cloath'd; and con$equently other Bodies,
not bigger then it, or longer then the in-
$ide of the Ve$$el. And this De$ign
$eem'd the more hopefull, becau$e I re-
membred, that having $everal years be-
fore often made the Experiment <I>De Va-
cuo</I> with my own hands; I had, to exa-
mine $ome conjectures that occurr'd to
me about it, cau$ed Gla$$es to be made
with a hole at that end, which u$es to be
$eal'd up, and had neverthele$s been able
<pb n=8>
as occa$ion requir'd, to make u$e of $uch
Tubes, as if no $uch holes had been left
in them; by devi$ing $topples for them,
made of the common Plai$ter call'd <I>Dia-
chylon:</I> which I rightly enough ghe$$'d,
would, by rea$on of the exqui$ite com-
mixtion of its $mall parts, and clo$ene$s
of its texture, deny all acce$s to the ex-
ternal Air. Wherefore, $uppo$ing that
by the help of $uch Plai$ters, carefully
laid upon the commi$$ures of the $topple
and hole to be made in the Receiver, the
external Air might be hindred from in$i-
nuating it $elf between them into the Ve$-
$el, we cau$'d $everal $uch Gla$$es, as
you will finde de$crib'd a little lower, to
be blown at the Gla$s-hou$e; and though
we could not get the Work-men to blow
any of them $o large, or of $o conveni-
ent a $hape as we would fain have had; yet
finding one to be tolerably fit, and le$s
unfit then any of the re$t, we were con-
tent to make u$e of it in that En-
gine: Of which, I $uppo$e, you by this
time expect the De$cription, in order to
the Recital of the <I>Ph&aelig;nomena</I> exhibited
by it.
<p>To give your Lord$hip then, in the
fir$t place, $ome account of the Engine it
<pb n=9>
$elf: It con$i$ts of two principal parts; a
gla$s Ve$$el, and a Pump to draw the Air
out of it.
<p>The former of the$e (which we, with
the Gla$s men, $hall often call a Receiver,
for its affinity to the large Ve$$els of that
name, u$ed by Chymi$ts) con$i$ts of a
Gla$s with a wide hole at the top, of a
cover to that hole, and of a $top-cock
fa$tned to the end of the neck, at the
bottom.
<p>The $hape of the Gla$s, you will find
expre$$'d in the fir$t Figure of the annex-
ed Scheme. And for the $ize of it, it
contain'd about 30 Wine Quarts, each of
them containing near two pound (of 16
Ounces to the pound) of water: We
$hould have been better plea$'d with a
more capacious Ve$$el, but the Gla$s-men
profe$$ed them$elves unable to blow a
larger, of $uch a thickne$s and $hape as
was requi$ite to our purpo$e.
<p>At the very top of the Ve$$el, (A) you
may ob$erve a round hole, who$e Dia-
meter (B C) is of about four inches; and
whereof, the Orifice is incircled with a
lip of Gla$s, almo$t an inch high: For
the making of which lip, it was requi$ite
(to mention that upon the by, in ca$e
<pb n=10>
your Lord$hip $hould have $uch another
Engine made for you) to have a hollow
and tapering Pipe of Gla$s drawn out,
whereof the Orifice above mentioned
was the Ba$is, and then to have the cone
cut off with a hot Iron, within about an
Inch of the Points (B C.)
<p>The u$e of the lip, is to $u$tain the
cover delineated in the $econd Figure;
where (D E) points out a bra$s Ring, $o
ca$t, as that it doth within and without
cover the lip (B C) of the fir$t Figure,
and is cemented on upon it with a $trong
and clo$e Cement. To the inward taper-
ing Orifice of this Ring (which is about
three Inches over) are exqui$itely ground
the $ides of the Bra$s $topple (F G;) $o
that the concave $uperficies of the one,
and the convex of the other, may touch
one another in $o many places, as may
leave as little acce$s, as po$$ible, to the ex-
ternal Air: And in the mid$t of this cover
is left a hole (H I) of about half an inch
over, invironed al$o with a ring or $ocket
of the $ame mettal, and fitted likewi$e
with a bra$s $topple (K) made in the form
of the Key of a $top-cock, and exactly
ground into the hole (H I) it is to fill; $o
as that though it be turn'd round in the
<pb n=11>
cavity it po$$e$$es, it will not let in the
Air, and yet may be put in or taken out
at plea$ure, for u$es to be hereafter men-
tioned. In order to $ome of which, it is
perforated with a little hole, (8) traver$ing
the whole thickne$s of it at the lower
end; through which, and a little bra$s
Ring (L) fa$tned to one $ide, (no matter
which) of the bottom of the $topple
(FG) a $tring (8, 9, 10) might pa$s, to
be imploy'd to move $ome things in the
capacity of the empty'd Ve$$el; without
any where un$topping it.
<p>The la$t thing belonging to our Recei-
ver, is the $top-cock de$igned in the fir$t
Figure by (N.) for the better fa$tening
of which to the neck, and exacter exclu$i-
on of the Air, there was $oder'd on to
the $hank of the Cock (X) a Plate of
Tin, (MTUW) long enough to cover
the neck of the Receiver. But becau$e
the cementing of this was a matter of
$ome difficulty, it will not be ami$s to
mention here the manner of it, which
was, That the cavity of the tin Plate was
fill'd with a melted Cement, made of
Pitch, Ro$in, and Wood-a$hes, well in-
corporated; and to hinder this liquid
Mixture from getting into the Orifice (Z)
<pb n=12>
of the $hank, (X) that hole was $topt
with a Cork, to which was fa$tned a $tring,
whereby it might be pull'd out of the up-
per Orifice of the Receiver; and then,
the gla$s neck of the Receiver being well
warm'd, was thru$t into this Cement, and
over the $hank whereby it was effected,
that all the $pace betwixt the tin Plate and
the Receiver, and betwixt the internal
$uperficies of the Receiver, and the
$hanck of the Cock, was filld with the
Cement; and $o we have di$pach'd the
fir$t and upper part of the Engine.
<p>The undermo$t remaining part con$i$ts
of a Frame, and of a $ucking Pump, or
as we formerly call'd it, an Air Pump, $up-
ported by it: The Frame is of Wood,
$mall, but very $trong, con$i$ting of three
legs, (111) $o plac'd, that one $ide of
it may $tand perpendicular, that the free
motion of the hand may not be hindered.
In the mid$t of which frame, is tran$ver$ly
nail'd a board, (222) which may not im-
properly be call'd a Midriff, upon which
re$ts, and to which is $trongly fa$tned, the
main part of the Pump it $elf, which is
the onely thing remaining to be de$cri-
bed.
<p>The Pump con$i$ts of four parts, a
<pb n=13>
hollow Cylindre, a Sucker, a handle to
move that Sucker, and a Valve.
<p>The Cylindre was (by a pattern) ca$t
of bra$s; it is in length about 14 inches,
thick enough to be very $trong, notwith-
$tanding the Cylindrical cavity left with-
in it; this cavity is about three inches
Diameter, and makes as exact a Cylin-
dre as the Artificer was able to bore.
This hollow Cylindre is fitted with a $uck-
er, (4455) con$i$ting of two parts, the
one (44) $omewhat le$s in Diameter then
the cavity of the Cylindre, upon which
is nail'd a good thick piece of tan'd $hoe
Leather, which will go $o clo$e to the
Cylindre, that it will need to be very
forcibly knock'd and ram'd in, if at any
time it be taken out, which is therefore
done, that it may the more exactly hin-
der the Air from in$inuating it $elf be-
twixt it and the $ides of the Cylindre
whereon it is to move.
<p>To the mid$t of this former part of the
Sucker is $trongly fa$tned the other,
namely a thick and narrow plate of Iron,
(55) $omewhat longer then the Cylindre,
one of who$e edges is $mooth, but at the
other edge it is indented (as I may $o
$peak) with a row of teeth delineated in
<pb n=14>
the Scheme, into who$e intervals are to
be fitted, the teeth of a $mall Iron nut;
(<*>) (as Trade$-men call it) which is fa$t-
ned by two $taples (22) to the under $ide
of the formerly mention'd tran$ver$e
board (222) on which the Cylindre re$ts,
and is turn'd to and fro by the third piece
of this Pump, namely, the handle or
<I>manubrium,</I> (7) of which the Figure gives
a $ufficient de$cription.
<p>The fourth and la$t part of this Cylin-
dre, is the Valve, (R) con$i$ting of a
hole bored through at the top of the Cy-
lindre, a little tapering towards the cavi-
ty; into which hole is ground a tapering
Peg of bra$s, to be thru$t in, and taken
out at plea$ure.
<p>The Engine being thus de$crib'd, it
will be requi$ite to adde, that $omething
is wont to be done before it be $et on
work, for the more ea$ie moving of the
Sucker, and for the better exclu$ion of
the outward Air: which when the Ve$$el
begins to be exhau$ted, is much more dif-
ficult to be kept out then one would ea$i-
ly imagine.
<p>There mu$t then be fir$t powr'd in at
the top of the Receiver a little $allad oyl,
partly to fill up any $mall intervalls that
<pb n=15>
may happen to be betwixt the contigu-
ous $urfaces of the internal parts of the
Stop-cock: And partly that it may be
the more ea$ie to turn the Key (S) back-
wards and forwards. Pretty $tore of oyl
mu$t al$o be pour'd into the Cylindre,
both that the Sucker may $lip up and
down in it the more $moothly and freely,
and that the Air might be the better
hindred from getting in between them:
And for the like rea$ons, a little oyl is to
be u$ed al$o about the Valve. Upon
which occa$ion, it would not be omitted
(for it is $trange) that oftentimes, when
neither the pouring in of water, nor even
of oyl alone, prov'd capable to make the
Sucker move ea$ily enough in the Cylin-
der; a mixture of both tho$e Liquors
would readily ($ometimes even to admi-
ration) perform the de$ired effect. And
la$tly, the bra$s cover of the Receiver,
being put into the bra$s ring formerly de-
$crib'd, that no Air may get between
them, it will be very requi$ite to plai$ter
over very carefully the upper edges of
both, with the plai$ter formerly mention-
ed, or $ome other as clo$e, which is to be
$pread upon the edges with a hot Iron;
that being melted, it may run into and
<pb n=16>
fill up all the crannies, or other little ca-
vities, at which the Air might otherwi$e
get entrance.
<p>All things being thus fitted, and the
lower $hank (O) of the $top-cock being
put into the upper Orifice of the Cylin-
der (&amp;), into which it was exactly ground;
the Experimenter is fir$t, by turning the
handle, to force the Sucker to the top of
the Cylinder, that there may be no Air
left in the upper part of it: Then $hut-
ting the Valve with the Plug, and turning
the other way, he is to draw down the
Sucker to the bottom of the Cylinder;
by which motion of the Sucker, the Air
that was formerly in the Cylinder being
thru$t out, and none being permitted to
$ucceed in its room, 'tis manife$t that the
cavity of the Cylinder mu$t be empty,
in reference to the Air: So that if there-
upon the Key of the Stop-cock be $o
turn'd, as that through the perforation of
it, a free pa$$age be opened betwixt the
Cylinder and the Receiver, part of the
Air formerly contain'd in the Receiver,
will nimbly de$cend into the Cylinder.
And this Air, being by the turning back
of the Key hinder'd from the returning
into the Receiver, may, by the opening
<pb n=17>
of the Valve, and forcing up of the Suck-
er to the top of the Cylinder again, be
driven out into the open Air. And thus
by the repetition of the motion of the
Sucker upward and downward, and by op-
portunely turning the Key, and $topping
the Valve, as occa$ion requires, more or
le$s Air may be $uck'd out of the Recei-
ver, according to the exigency of the Ex-
periment, and the intention of him that
makes it.
<p>Your Lord$hip will, perhaps, think that
I have been unnece$$arily prolix in this
fir$t part of my Di$cour$e: But if you
had $een how many unexpected difficul-
ties we found to keep out the externall
Air, even for a little while, when $ome
con$iderable part of the internal had been
$uckt out; You would peradventure al-
low, that I might have $et down more
circum$tances then I have, without $et-
ting down any, who$e knowledge, he that
$hall try the Experiment may not have
need of. Which is $o true, that, before we
proceed any further, I cannot think it un-
$ea$onable to adverti$e Your Lord$hip,
that there are two chief $orts of Experi-
ments, which we de$ign'd in our Engine
to make tryal of: The one, $uch as may
<pb n=18>
be quickly di$patcht, and therefore may
be try'd in our Engine, though it leak a
little; becau$e the Air may be fa$ter drawn
out, by nimbly plying the Pump, then
it can get in at undi$cern'd leaks; I $ay at
undi$cern'd leaks, becau$e $uch as are big
enough to be di$cover'd can $carce be un-
ea$ie to be $topt. The other $ort of Ex-
periments con$i$ts of tho$e that require
not onely that the internal Air be drawn
out of the Receiver, but that it be like-
wi$e for a long time kept out of it. Such
are the pre$ervation of Animal and o-
ther Bodies therein, the germination and
growth of Vegetables, and other tryals
of $everal $orts, which it is apparent can-
not be well made unle$s the external Air
can, for a competent while, be excluded:
Since even at a very $mall leak there may
enough get in, to make the <I>Vacuum</I> $oon
loo$e that name; by which I here declare
once for all, that I under$tand not a $pace
wherein there is no body at all, but $uch
as is either altogether, or almo$t totally
void of Air.
<p>Now this di$tinction of Experiments
I thought fit to premi$e to the en$uing
Narratives, becau$e upon tryal, we found
it $o exceeding (and $carce imaginable) dif-
<pb n=19>
ficult a matter, to keep out the Air from
getting at all in at any imperceptible hole
or flaw what$oever, in a Ve$$el immedi-
ately $urrounded with the compre$$ed At-
mo$phere, that in $pight of all our care
and diligence, we never were able totally
to exhau$t the Receiver, or keep it when
it was almo$t empty, any con$iderable
time, from leaking more or le$s: although
(as we have lately intimated) by unwearyed
quickne$s in plying the Pump, the inter-
nall Air can be much fa$ter drawn out
then the external can get in, till the Re-
ceiver come to be almo$t quite empty.
And that's enough to enable men to di$-
cover hitherto unob$erved <I>Ph&aelig;nomena</I> of
Nature.
<p>The Experiments therefore of the fir$t
$ort, will, I fear, prove the onely ones
wherewith my Avocations will allow me
to entertain Your Lord$hip in this Letter.
For till your further Commands $hall en-
gage me to undertake, by Gods permi$-
$ion, $uch an Employment, and more lea-
$ure $hall better fit me for it, I know not
whether I $hall be in a condition to try
what may be done, to enable me to give
you $ome account of the other $ort of
Experiments al$o.
<pb n=20>
<p>TO proceed now to the <I>Ph&aelig;nomena,</I>
<MARG><I>Experi-
ment</I> 1.</MARG>
exhibited to us by the Engine above
de$cribed; I hold it not unfit to begin
with what does con$tantly and regularly
offer it $elf to our ob$ervation, as depend-
ing upon the Fabrick of the Engine it $elf,
and not upon the nature of this or that
particular Experiment which 'tis employ-
ed to try.
<p>Fir$t, Then upon the drawing down
of the Sucker, (the Valve being $hut) the
Cylindrical $pace, de$erted by the Sucker,
is left de void of Air; and therefore, up-
on the turning of the Key, the Air con-
tained in the Receiver ru$hes into the em-
ptyed Cylinder, till the Air in both tho$e
Ve$$els be brought to about an equal
mea$ure of dilatation. And therefore,
upon $hutting the Receiver by returning
the Key, if you open the Valve, and force
up the Sucker again, you will finde, that
after this fir$t ex$uction you will drive
out almo$t a whole Cylinder full of Air:
But at the following ex$uctions, you will
draw le$s and le$s of Air out of the Recei-
ver into the Cylinder, becau$e that there
will $till remain le$s and le$s Air in the
<pb n=21>
Receiver it $elf; and con$equently, the
Particles of the remaining Air, having
more room to extend them$elves in, will
le$s pre$s out one another. This you will
ea$ily perceive, by finding, that you $till
force le$s and le$s Air out of the Cylin-
der; $o that when the Receiver is almo$t
exhau$ted, you may force up the Sucker
almo$t to the top of the Cylinder, be-
fore you will need to un$top the Valve to
let out any Air: And if at $uch time, the
Valve being $hut, you let go the handle of
the Pump, you will finde the Sucker for-
cibly carryed up to the top of the Cylin-
der, by the protru$ion of the external Air;
which, being much le$s rarified then that
within the Cylinder, mu$t have a more
forcible pre$$ure upon the Sucker, then
the internal is able to re$i$t: And by this
means you may know how far you have
emptyed the Receiver. And to this we
may adde, on this occa$ion, that con$tant-
ly upon the turning of the Key to let out
the Air from the Receiver, into the em-
ptied Cylinder, there is immediately pro-
duced a con$iderably brisk noi$e, e$peci-
ally whil'$t there is any plenty of Air in
the Receiver.
<pb n=22>
<p>For the more ea$ie under$tanding of the
Experiments tryable by our Engine, I
thought it not $uperfluous, nor un$ea$on-
able in the recital of this fir$t of them, to
in$inuate that notion by which it $eems
likely that mo$t, if not all, of them will
prove explicable. Your Lord$hip will
ea$ily $uppo$e, that the Notion I $peak
of is, That there is a Spring, or Ela$ti-
cal power in the Air we live in. By which
<G>e)latg\r</G> or Spring of the Air, that which
I mean is this: That our Air either con-
$i$ts of, or at lea$t abounds with, parts of
$uch a nature, that in ca$e they be bent or
compre$$'d by the weight of the incum-
bent part of the Atmo$phere, or by any o-
ther Body, they do endeavor, as much as
in them lies, to free them$elves from that
pre$$ure, by bearing again$t the contigu-
ous Bodies that keep them bent; and,
a$$oon as tho$e Bodies are remov'd or
reduced to give them way, by pre$ently
unbending and $tretching out them$elves,
either quite, or $o far forth as the con-
tiguous Bodies that re$i$t them will per-
mit, and thereby expanding the whole
parcel of Air, the$e ela$tical Bodies com-
po$e.
<pb n=23>
<p>This Notion may perhaps be $ome-
what further explain'd, by conceiving the
Air near the Earth to be $uch a heap of
little Bodies, lying one upon another, as
may be re$embled to a Fleece of Wooll.
For this (to omit other likene$$es betwixt
them) con$i$ts of many $lender and flexi-
ble Hairs; each of which, may indeed,
like a little Spring, be ea$ily bent or roul-
ed up; but will al$o, like a Spring, be
$till endeavouring to $tretch it $elf out
again. For though both the$e Haires,
and the Aerial Corpu$cles to which we
liken them, do ea$ily yield to externall
pre$$ures; yet each of them (by vertue of
its $tructure) is endow'd with a Power or
Principle of $elf-Dilatation; by vertue
whereof, though the hairs may by a Mans
hand be bent and crouded clo$er together,
and into a narrower room then $uits be$t
with the nature of the Body: Yet whil'$t
the compre$$ion la$ts, there is in the fleece
they compo$e an endeavour outwards,
whereby it continually thru$ts again$t the
hand that oppo$es its Expan$ion. And
upon the removall of the external pre$-
$ure, by opening the hand more or le$s, the
compre$$ed Wooll does, as it were, $pon-
taneou$ly expand or di$play it $elf towards
<pb n=24>
the recovery of its former more loo$e and
free condition, till the Fleece have ei-
ther regain'd its former Dimen$ions, or
at lea$t, approach'd them as near as the
compre$$ing hand (perchance not quite
open'd) will permit. This Power of
$elf-Dilatation, is $omewhat more con$pi-
cuous in a dry Spunge compre$$'d, then
in a Fleece of Wooll. But yet we ra-
ther cho$e to imploy the latter, on this
occa$ion, becau$e it is not like a Spunge,
an entire Body, but a number of $len-
der and flexible Bodies, loo$ely com-
plicated, as the Air it $elf $eems to
be.
<p>There is yet another way to explicate
the Spring of the Air, namely, by $uppo-
$ing with that mo$t ingenious Gentleman,
Mon$ieur <I>Des Cartes,</I> That the Air is no-
thing but a Congeries or heap of $mall
and (for the mo$t part) of flexible Parti-
cles; of $everal $izes, and of all kinde of Fi-
gures which are rai$'d by heat (e$pecially
that of the Sun) into that fluid and
$ubtle Etheriall Body that $urrounds
the Earth; and by the re$tle$$e agi-
tation of that Cele$tial Matter where-
in tho$e Particles $wim, are $o whirl'd
<pb n=25>
round, that each Corpu$cle endeavours
to beat off all others from coming within
the little Sphear requi$ite to its motion
about its own Center; and (in ca$e any,
by intruding into that Sphear $hall op-
po$e its free Rotation) to expell or drive
it away: So that according to this Do-
ctrine, it imports very little, whether the
particles of the Air have the $tructure re-
qui$ite to Springs, or be of any other
form (how irregular $oever) $ince their
Ela$tical power is not made to depend
upon their $hape or $tructure, but upon
the vehement agitation, and (as it were)
brandi$hing motion, which they receive
from the fluid <I>Ether</I> that $wiftly flows
between them, and whirling about each
of them (independently from the re$t)
not onely keeps tho$e $lender A&euml;rial
Bodies $eparated and $tretcht out (at lea$t,
as far as the Neighbouring ones will per-
mit) which otherwi$e, by rea$on of
their flexiblene$s and weight, would
flag or curl; but al$o makes them hit
again$t, and knock away each other, and
con$equently require more room, then
that which if they were compre$$'d, they
would take up.
<pb n=26>
<p>By the$e two differing ways, my Lord,
may the Spring of the Air be explicated.
But though the former of them be that,
which by rea$on of its $eeming $omewhat
more ea$ie, I $hall for the mo$t part make
u$e of in the following Di$cour$e: yet
am I not willing to declare peremptorily
for either of them, again$t the other. And
indeed, though I have in another Treati$e
endeavoured to make it probable, that the
returning of Ela$tical Bodies (if I may $o
call them) forcibly bent, to their former
po$ition, may be Mechanically explica-
ted: Yet I mu$t confe$s, that to deter-
mine whether the motion of Re$titution
in Bodies, proceed from this, That the
parts of a Body of a peculiar Structure
are put into motion by the bending of the
$pring, or from the endeavor of $ome $ub-
tle ambient Body, who$e pa$$age may be
oppo$'d or ob$tructed, or el$e it's pre$$ure
unequally re$i$ted by rea$on of the new
$hape or magnitude, which the bending of
a Spring may give the Pores of it: To
determine this, I $ay, $eems to me a mat-
ter of more difficulty, then at fir$t $ight
one would ea$ily imagine it. Wherefore
I $hall decline medling with a $ubject,
which is much more hard to be explica-
<pb n=27>
ted, then nece$$ary to be $o, by him,
who$e bu$ine$s it is not, in this Letter, to
a$$ign the adequate cau$e of the Spring of
the Air, but onely to manife$t, That the
Air has a Spring, and to relate $ome of
its effects.
<p>I know not whether I need annex that,
though either of the above-mention'd
Hypothe$es, and perhaps $ome others,
may afford us an account plau$ible enough
of the Air-$pring; yet I doubt, whether
any of them gives us a $ufficient account
of its Nature. And of this doubt, I
might here mention $ome Rea$ons, but
that, peradventure, I may (God permit-
ting) have a fitter occa$ion to $ay $ome-
thing of it el$ewhere. And therefore I
$hould now proceed to the next Experi-
ment, but that I think it requi$ite, fir$t,
to $ugge$t to your Lord$hip what comes
into my thoughts, by way of An$wer to
a plau$ible Objection, which I fore$ee you
may make again$t our propo$'d Doctrine,
touching the Spring of the Air. For it
may be alleadged, that though the Air
were granted to con$i$t of Springy Par-
ticles (if I may $o $peak) yet thereby
we could onely give an account of the
Dilatation of the Air in Wine-Guns and
<pb n=28>
other pneumatical Engines wherein the
Air has been compre$$'d, and its Springs
violently bent by an apparent externall
force; upon the removall of which, 'tis
no wonder that the Air $hould, by the
motion of re$titution, expand it $elf till
it have recovered its more natural dimen-
$ions: whereas in our above-mentioned
fir$t Experiment, and in almo$t all others
tryable in our Engine, it appears not
that any compre$$ion of the Air prece-
ded its $pontaneous Dilatation or Expan-
$ion of it $elf. To remove this difficul-
ty, I mu$t de$ire Your Lord$hip to take
notice, that of whatever nature the Air,
very remote from the Earth, may be, and
whatever the Schools may confidently
teach to the contrary, yet we have divers
Experiments to evince, that the Atmo$-
phere we live in is not (otherwi$e then
comparatively to more ponderous Bodies)
light, but heavy: And did not their
gravity hinder them, it appears not why
the $teams of the Terraqueous Globe, of
which our Air in great part con$i$ts,
$hould not ri$e much higher then the Re-
fraction of the Sun, and other Stars
give men ground to think, that the At-
mo$phere, even in the judgement of tho$e
<pb n=29>
Recent A$tronomers, who $eem willing
to enlarge its bounds as much as they dare,
does reach.
<p>But le$t you $hould expect my $econding
this Rea$on by Experience; and le$t you
$hould object, That mo$t of the Experi-
m&etilde;ts that have been propo$'d to prove the
gravity of the Air, have been either barely
propo$'d, or perhaps not accuratly try'd; I
am content, before I pa$s further, to menti-
on here, That I found a dry lambs-bladder
containing near about two thirds of a pint,
and compre$$'d by a packthred tyed about
it, to loo$e a grain and the eighth part of
a grain of its former weight, by the rece$s
of the Air upon my having prickt it: And
this with a pair of Scales, which when the
full Bladder and the corre$pondent weight
were in it, would manife$tly turn either
way with the 32 part of a grain. And if
it be further objected, That the Air in
the Bladder was violently compre$$'d by
the Pack-thred and the $ides of the
Bladder, we might probably (to wave
prolix an$wers) be furni$h'd with a Re-
ply, by $etting down the differing weight
of our Receiver, when empty'd and when
full of uncompre$$'d Air, if we could here
procure $cales fit for $o nice an experiment;
<pb n=30>
$ince we are informed, that in the <I>German</I>
Experiment, commended at the begin-
ning of this Letter, the Ingenious Tryers
of it found, That their Gla$s Ve$$el, of
the capacity of 32 mea$ures, was lighter
when the Air had been drawn out of it,
then before, by no le$s then one ounce
and (3/10) that is, an ounce and very near a
third: But of the gravity of the Air, we
may el$ewhere have occa$ion to make fur-
ther mention.
<p>Taking it then for granted that the Air
is not deyoid of weight, it will not be
unea$ie to conceive, that that part of the
Atmo$phere wherein we live, being the
lower part of it, the Corpu$cles that com-
po$e it, are very much compre$$'d by the
weight of all tho$e of the like nature that
are directly over them, that is, of all the
Particles of Air, that being pil'd up up-
on them, reach to the top of the Atmo$-
phere. And though the height of this
Atmo$phere, according to the famous
<I>Kepler,</I> and $ome others, $carce exceeds
eight common miles; yet other eminent
and later A$tronomers, would promote
the confines of the Atmo$phere, to ex-
ceed $ix or $even times t<*> number of
miles. And the diligent and learned
<pb n=31>
<I>Riviolo</I> makes it probable, that the At-
mo$phere may, at lea$t in divers places, be
at lea$t 50 miles high. So that according to
a moderate e$timate of the thickne$s of
the Atmo$phere, we may well $uppo$e,
that a Column of Air, of many miles in
height, leaning upon $ome $pringy Cor-
pu$cles of Air here below, may have
weight enough to bend their little $prings,
and keep them bent: As, to re$ume our
former compari$on, if there were fleeces of
Wooll pil'd up to a mountainous height
upon one another, the Hairs that com-
po$e the lowermo$t locks which $upport
the re$t, would, by the weight of all the
Wool above them, be as well $trongly
compre$$ed, as if a man $hould $queeze
them together in his hands, or imploy any
$uch other moderate force to compre$s
them. So that we need not wonder, that
upon the taking off the incumbent Air
from any parcel of the Atmo$phere here
below, the Corpu$cles, whereof that un-
dermo$t Air con$i$ts, $hould di$play them-
$elves, and take up more room then be-
fore.
<p>And if it be objected, That in Water,
the weight of the upper and of the lower
part is the $ame: I an$wer, That be$ides
<pb n=32>
that it may be well doubted whether the
ob$ervation, by rea$on of the great diffi-
culty have been exactly made, there is a
manife$t di$parity betwixt the Air and
Water: For I have not found, that upon
an Experiment purpo$ely made, (and in
another Treati$e Recorded) that Water
will $uffer any con$iderable compre$$ion;
whereas we may ob$erve in Wind-Guns
(to mention now no other Engines) that
the Air will $uffer it $elf to be crouded in-
to a comparatively very little room; in
$o much, that a very diligent Examiner
of the <I>Ph&aelig;nomena</I> of Wind-Guns would
have us believe, that in one of them, by
conden$ation, he reduc'd the Air into a
$pace at lea$t eight times narrower then it
before po$$e$t. And to this, if we adde
a noble <I>Ph&aelig;nomenon</I> of the Experiment
<I>De Vacuo;</I> the$e things put together, may
for the pre$ent $uffice to countenance our
Doctrine. For that noble Experimenter,
Mon$ieur <I>Pa$cal</I> (the Son) had the com-
mendable Curio$ity to cau$e the <I>Torri-
cellian</I> Experiment to be try'd at the foot,
about the middle, and at the top of that
high Mountain (in <I>Auvergne,</I> if I mi$take
not) commonly call'd <I>Le Puy de Domme;</I>
whereby it was found, That the <I>Mercury</I>
<pb n=33>
in the Tube fell down lower, about three
inches, at the top of the Mountain then
at the bottom. And a Learned Man a
while $ince inform'd me, That a great
<I>Virtuo$o,</I> friend to us both, has, with not
unlike $ucce$s, tryed the $ame Experi-
ment in the lower and upper parts of a
Mountain in the We$t of <I>England:</I> Of
which, the rea$on $eems manife$tly enough
to be this, That upon the tops of high
Mountains, the Air which bears again$t
the re$tagnant Quick-$ilver, is le$s pre$$'d
by the le$s ponderous incumbent Air; and
con$equently is not able totally to hinder
the de$cent of $o tall and heavy a Cylin-
der of Quick-$ilver, as at the bottom of
$uch Mountains did but maintain an <I>&AElig;qui-
librium</I> with the incumbent Atmo$phere.
<p>And if it be yet further Objected a-
gain$t what hath been propo$'d touching
the compactne$s and pre$$ure of the Infe-
rior Air; That we finde this very Air to
yield readily to the motion of little Flies,
and even to that of Feathers, and $uch o-
ther light and weak Bodies; which $eems
to argue, that the particles of our Air are
not $o compre$$'d as we have repre$ented
them, e$pecially, $ince by our former
Experiment it appears, that the Air rea-
<pb n=34>
dily dilated it $elf downward, from the
Receiver into the Pump, when 'tis plain,
that it is not the incumbent Atmo$phere,
but onely the $ubjacent Air in the bra$s
Cylinder that has been remov'd: If this,
I $ay, be objected, we may reply, That
when a man $queezes a Fleece of Wool in
his hand, he may feel that the Wool in-
ce$$antly bears again$t his hand, as that
which hinders the hairs it con$i$ts of, to
recover their former and more natural ex-
tent. So each parcel of the Air about the
Earth, does con$tantly endeavour to thru$t
away all tho$e contiguous Bodies, whe-
ther A&euml;rial or more gro$s, that keep
them bent, and hinder the expan$ion of
its parts, which will dilate them$elves or
flie abroad towards that part, whether up-
wards or downwards, where they finde
their attempted Dilatation of them$elves
le$s re$i$ted by the neihgboring Bodies.
Thus the Corpu$cles of that Air we have
been all this while $peaking of, being un-
able, by rea$on of their weight, to a$cend
above the Convexity of the Atmo$phere,
and by rea$on of the re$i$tance of the $ur-
face of the Earth and Water, to fall down
lower, they are forced, by their own gra-
vity and this re$i$tance, to expand and
<pb n=35>
diffu$e them$elves about the Terre$tial
Globe; whereby it comes to pa$s, that
they mu$t as well pre$s the contiguous
Corpu$cles of Air that on either $ide op-
po$e their Dilatation, as they mu$t pre$s
upon the $urface of the Earth, and, as it
were recoyling thence, endeavor to thru$t
away tho$e upper particles of Air that
lean upon them.
<p>And as for the ea$ie yielding of the Air
to the Bodies that move in it, if we con-
$ider that the Corpu$cles whereof it con-
$i$ts, though of a $pringy nature, are yet
$o very $mall, as to make up (which 'tis
manife$t they doe) a fluid Body, it will
not be difficult to conceive, that in the
Air, as in other Bodies that are fluid, the
little Bodies it con$i$ts of are in an almo$t
re$tle$s motion, whereby they become
(as we have more fully di$cour$ed in ano-
<MARG><I>In a Di$-
cour$e
touching
$luidity
and firm-
ne$s.</I></MARG>
ther Treati$e) very much di$po$ed to
yield to other Bodies, or ea$ie to be di$-
plac'd by them, and that the $ame Cor-
pu$cles are likewi$e $o variou$ly mov'd, as
they are intire Corpu$cles, that if $ome
$trive to pu$h a Body plac'd among them
towards the right hand (for in$tance)
others, who$e motion has an oppo$ite de-
termination, as $trongly thru$t the $ame
<pb n=36>
Body towards the left; whereby neither
of them proves able to move it out of
its place, the pre$$ure on all hands being
reduced as it were to an <I>&AElig;quilibrium:</I> $o
that the Corpu$cles of the Air mu$t be as
well $ometimes con$idered under the no-
tion of little Springs, which remaining
bent, are in their entire bulk tran$ported
from place to place; as under the notion
of Springs di$playing them$elves, who$e
parts flie abroad whil$t as to their entire
bulk they $carce change place: As the
two ends of a Bow, $hot off, fly from one
another, whereas the Bow it $elf may be
held fa$t in the Archers hand; and that it
is the equal pre$$ure of the Air on all $ides
upon the Bodies that are in it, which cau-
$es the ea$ie Ce$$ion of its parts, may be
argu'd from hence: That if by the help
of our Engine the Air be but in great
part, though not totally drawn away
from one $ide of a Body without being
drawn away from the other; he that $hall
think to move that Body too and fro, as
ea$ily as before, will finde him$elf much
mi$taken.
<p>In verification of which we will, to di-
vert your Lord$hip a little, mention here
a <I>Ph&aelig;nomenon</I> of our Engine, which even
<pb n=37>
to divers ingenious per$ons has at fir$t
$ight $eem'd very wonderful.
<p>THe thing that is wont to be admired,
<MARG><I>Experi-
ment</I> 2.</MARG>
and which may pa$s for our $econd
Experiment is this, That if, when the
Receiver is almo$t empty, a By-$tander
be de$ired to lift up the bra$s Key (former-
ly de$cribed as a $topple in the bra$s Co-
ver) he will finde it a very difficult thing
to do $o, if the Ve$$el be well exhau$ted;
and even when but a moderate quantity of
Air has been drawn out, he will, when he
has lifted it up a little, $o that it is $ome-
what loo$e from the $ides of the lip or
$ocket, which (with the help of a little
oyl) it exactly filled before, he will (I $ay)
finde it $o difficult to be lifted up, that
he will imagine there is $ome great weight
fa$tned to the bottom of it. And if (as
$ometimes has been done for merriment)
onely a Bladder be tyed to it, it is plea-
$ant to $ee how men will marvail that $o
light a Body, filled at mo$t but with Air,
$hould $o forcibly draw down their hand
as if it were fill'd with $ome very ponder-
ous thing: whereas the cau$e of this pret-
ty <I>Ph&aelig;nomenon</I> $eems plainly enough to
<pb n=38>
be onely this, That the Air in the Recei-
ver, being very much dilated, its Spring
mu$t be very much weakn'd, and con$e-
quently it can but faintly pre$s up the
lower end of the $topple, whereas the
Spring of the external Air being no way
debilitated, he that a little lifts up the
$topple mu$t with his hand $upport a pre$-
$ure equal to the di$proportion betwixt
the force of the internal expanded Air, and
that of the Atmo$phere incumbent upon
the upper part of the $ame key or $topple:
And $o men being unu$'d to finde any re-
$i$tance, in lifting things up, from the
free Air above them, they are forward to
conclude that that which depre$$es their
hands mu$t needs be $ome weight, though
they know not where plac'd, drawing be-
neath it.
<p>And that we have not mi$-a$$ign'd the
cau$e of this <I>Ph&aelig;nomenon</I> $eems evident
enough by this; That as Air is $uffer-
ed by little and little to get into the Re-
ceiver, the weight that a man fancies his
hand $upports is manife$tly felt to decrea$e
more and more, the internal Air by this
recruit approaching more to an <I>&AElig;quili-
brium</I> with the external, till at length the
Receiver growing again full of Air, the
<pb n=39>
$topple may be lifted up without any dif-
ficulty at all.
<p>By $everal other of the Experiments
afforded us by our Engine, the $ame no-
tion of the great and equal pre$$ure of the
free Air upon the Bodies it environs,
might be here manife$ted, but that we
think it not $o fit to anticipate $uch Ex-
periments: And therefore $hall rather
employ a few lines to clear up a difficulty
touching this matter, which we have ob-
$erv'd to have troubled $ome even of the
Philo$ophical and Mathematical Specta-
tors of our Engine, who have wonder'd
that we $hould talk of the Air exqui$itely
$hut up in our Receiver, as if it were all
one with the pre$$ure of the Atmo$phere;
whereas the thick and clo$e body of the
Gla$s, wholly impervious to the Air, does
manife$tly keep the incumbent Pillar of
the Atmo$phere from pre$$ing in the lea$t
upon the Air within the Gla$s, which it
can no where come to touch. To eluci-
date a little this matter, let us con$ider,
That if a man $hould take a fleece of
Wool, and having fir$t by compre$$ing it
in his hand reduc'd it into a narrower com-
pa$s, $hould nimbly convey and $hut it
clo$e up into a Box ju$t fit for it, though
<pb n=40>
the force of his hand would then no lon-
ger bend tho$e numerous $pringy Body's
that compo$e the Fleece, yet they would
continue as $trongly bent as before, be-
cau$e the Box they are inclo$'d in would
as much re$i$t their re-expanding of
them$elves, as did the hand that put them
in. For thus we may conceive, that the
Air being $hut up, when its parts are bent
by the whole weight of the incumbent
Atmo$phere, though that weight can no
longer lean upon it, by rea$on it is kept
off by the Gla$s, yet the Corpu$cles of
the Air within that Gla$s continue as
forcibly bent as they were before their in-
clu$ion, becau$e the $ides of the Gla$s
hinder them from di$playing or $tretch-
ing out them$elves. And if it be ob-
jected that this is unlikely, becau$e ev'n
Gla$s bubles, $uch as are wont to be
blown at the flame of a Lamp, exceeding
thin and Hermetically $eal'd will not
break; whereas it cannot be imagin'd
that $o thin a Pri$on of Gla$s could re-
$i$t the Ela$tical force of all the included
Air, if that Air were $o compre$$'d as we
$uppo$e. It may be ea$ily reply'd, That
the pre$$ure of the inward Air again$t the
Gla$s, is countervail'd by the equal pre$-
<pb n=41>
$ure of the outward again$t the $ame Gla$s.
And we $ee in bubles, that by rea$on of
this an exceeding thin film of Water is
often able, for a good while, to hinder the
eruption of a pretty quantity of Air. And
this may be al$o more con$picuous in
tho$e great Spherical bubles that boyes
$ometimes blow with Water, to which
Sope has given a Tenacity. But that, if the
pre$$ure of the ambient Air were remov'd,
the internal Air may be able to break
thicker Gla$$es then tho$e lately men-
tion'd, will appear by $ome of the follow-
ing Experiments; to which we $hall there-
fore now ha$ten, having, I fear, been but
too prolix in this Excur$ion, though we
thought it not ami$s to annex to our fir$t
Experiments $ome general Con$iderati-
ons touching the Spring of the Air, be-
cau$e (this Doctrine being yet a $tranger
to the Schools) not onely we finde not
the thing it $elf to be much taken notice
of; but of tho$e few that have heard of it,
the greater part have been forward to re-
ject it, upon a mi$taken Per$wa$ion, that
tho$e <I>Ph&aelig;nomena</I> are the effects of natures
abhorrency of a <I>Vacuum,</I> which $eem to
be more fitly a$cribeable to the weight
and Spring of the Air.
<pb n=42>
<p>WE will now proceed to ob$erve that
<MARG><I>Experi-
ment</I> 3.</MARG>
though, by the help of the handle,
the Sucker be ea$ily drawn down to the
bottom of the Cylinder; yet, without
the help of that Leaver, there would be
required to the $ame effect, a force or
weight great enough to $urmount the
pre$$ure of the whole Atmo$phere: Since
otherwi$e the Air would not be driven out
of its place, when none is permitted to
$ucceed into the place de$erted by the
Sucker. This $eems evident, from the
known <I>Torricellian</I> Experiment, in which,
if the inverted Tube of <I>Mercury</I> be but
25 Digits high, or $omewhat more, the
Quick-$ilver will not fall but remain $u$-
pended in the Tube; becau$e it cannot
pre$s the $ubjacent <I>Mercury</I> with $o great
a force, as does the incumbent Cylinder
of the Air reaching thence to the top of
the Atmo$phere: Whereas, if the Cy-
linder of <I>Mercury</I> were three or four digits
longer, it would over-power that of the
external Air, and run out into the Ve$$el'd
<I>Mercury,</I> till the two Cylinders came to
an <I>&AElig;quilibrium,</I> and no further. Hence
we need not wonder, that though the
<pb n=43>
Sucker move ea$ily enough up and down
in the Cylinder by the help of the <I>Manu-
brium;</I> yet if the <I>Manubrium</I> be taken off,
it will require &amp; con$iderable $trength to
move it either way. Nor will it $eem
$trange, that if, when the Valve and
Stop-cock are well $hut, you draw down
the Sucker, and then let go the <I>Manubri-
um;</I> the Sucker will, as it were of it $elf,
re-a$cend to the top of the Cylinder, $ince
the $pring of the external Air findes no-
thing to re$i$t its pre$$ing up the Sucker.
And for the $ame rea$on, when the Re-
ceiver is almo$t evacuated, though, ha-
ving drawn down the Sucker, you open
the way from the Receiver to the Cylin-
der, and then intercept that way again by
returning the Key; the Sucker will, up-
on the letting go the <I>Manubrium,</I> be
forcibly carried up almo$t to the top of
the Cylinder: Becau$e the Air within the
Cylinder, being equally dilated and weak-
ned with that of the Gla$s, is unable to
with$tand the pre$$ure of the external Air,
till it be driven into $o little $pace, that
there is an <I>&AElig;quilibrium</I> betwixt its force
and that of the Air without. And con-
gruou$ly hereunto we finde, that in this
ca$e, the Sucker is drawn down with little
<pb n=44>
le$s difficulty, then if the Cylinder, be-
ing devoid of Air, the Stop-cock were
exactly $hut: We might take notice of
$ome other things, that depend upon the
Fabrick of our Engine it $elf; but to $hun
prolixity, we will, in this place, content
our $elves to mention one of them, which
$eems to be of greater moment then the
re$t, and it is this; that when the Sucker
has been impell'd to the top of the Cylin-
der, and the Valve is $o carefully $topp'd,
that there is no Air left in the Cylinder a-
bove the Sucker: If then the Sucker be
drawn to the lower part of the Cylinder,
he that manages the Pump findes not any
$en$ibly greater difficulty to depre$s the
Sucker, when it is nearer the bottom of the
Cylinder, then when it is much further off.
Which circum$tance we therefore think fit
to take notice of, becau$e an eminent Mo-
dern Naturali$t hath taught, that, when the
Air is $ucked out of a Body, the violence
wherewith it is wont to ru$h into it again,
as $oon as it is allow'd to re-enter, pro-
ceeds mainly from this; That the pre$$ure
of the ambient Air is $trengthned upon
the acce$$ion of the Air $uck'd out; which,
to make it $elf room, forces the neighbor-
ing Air to a violent-$ubingre$$ion o$ its
parts: which, i$ it were true, he that draws
<pb n=45>
down the Sucker, would finde the re$i$t-
ance of the external Air increa$'d as he
draws it lower, more of the di$placed Air
being thru$t into it to compre$s it. But, by
what has been di$cour$'d upon the fir$t
Experiment, it $eems more probable, that
without any $uch $trengthning of the pre$-
$ure of the outward Air, the taking quite
away or the debilitating of the re$i$tance
from within, may $uffice to produce the
effects under con$ideration. But this will
perhaps be illu$trated by $ome or other of
our future Experiments, and therefore
$hall be no longer in$i$ted on here.
<p>HAving thus taken notice of $ome of
<MARG><I>Experi-
ment</I> 4.</MARG>
the con$tant <I>Ph&aelig;nomena</I> of our En-
gine it $elf, let us now proceed to the Ex-
periments tryable in it.
<p>We took then a Lambs Bladder large,
well dry'd, and very limber, and leaving in
it about half as much Air as it could con-
tain, we cau$'d the neck of it to be $trong-
ly ty'd, $o that none of the included Air,
though by pre$$ure, could get out. This
Bladder being convey'd into the Receiver,
and the Cover luted on, the Pump
was $et awork, and after two or three
ex$uctions of the ambient Air (where-
by the Spring of that which remain'd in
<pb n=46>
the Gla$s was weaken'd) the Impri$on'd
Air began to $well in the Bladder, and as
more and more of the Air in the Recei-
ver was, from time to time, drawn out; $o
did that in the Bladder more and more ex-
pand it $elf, and di$play the folds of the
formerly flaccid Bladder: $o that before we
had exhau$ted the Receiver near $o much
as we could, the Bladder appear'd as full
and $tretched, as if it had been blown up
with a Quill.
<p>And that it may appear that this plump-
ne$s of the Bladder proceeded from the
$urmounting of the debilitated Spring of
the ambient Air remaining in the Ve$$el,
by the $tronger Spring of the Air remain-
ing in the Bladder; we Return'd the Key
of the Stop-cock, and by degrees allow'd
the external Air to return into the Recei-
ver: Whereupon it happen'd, as was ex-
pected, that as the Air came in from with-
out, the di$turb'd Air in the Bladder, was
proportionably compre$$'d into a narrow-
er room, and the $ides of the Bladder
grew flaccid, till the Receiver having re-
admitted its wonted quantity of Air, the
Bladder appear'd as full of wrinkles and
cavities as before.
<pb n=47>
<p>This Experiment is much of the $ame
nature with that which was $ome years
agoe $aid to be made by that eminent Ge-
ometrician Mon$ieur <I>Roberval,</I> with a
Carps Bladder empty'd and convey'd into
a Tube, wherein the Experiment <I>De Va-
cuo</I> was afterwards try'd, which ingeni-
ous Experiment of his ju$tly de$erves the
thanks of tho$e that have been, or $hall be
$olicitous to di$cover the nature of the
Air.
<p>But to return to our Experiment, we
may take notice of this Circum$tance in
it, That after the Receiver has been in
$ome mea$ure empty'd, the Bladder do's,
at each ex$uction, $well much more con-
$picuou$ly then it did at any of the fir$t
Ex$uctions; in$omuch that towards the
end of the pumping, not onely a great
fold or cavity in the $urface of the Blad-
der may be made, even by the $tretching
of the inward $elf-expanding Air: But
we have $ometimes $een, upon the turn-
ing of the Key to let the ambient Air
pa$s out of the Receiver into the Cylin-
der, we have $een (I $ay) the Air in the
Bladder $uddenly expand it $elf $o much
and $o briskly, that it manife$tly lifted up
$ome light Bodies that lean'd upon it,
<pb n=48>
and $eem'd to lift up the Bladder it
$elf.
<p>Now becau$e it has by very Learned
Men been doubted whether the $welling
of the Bladder may not have proceeded
from the Dilatation of the included Air,
but from the Texture of the Fibres,
which, being wont to keep the Bladder
extended when the Animal to whom it
belong'd was alive, may be $uppo$'d in
our Experiment to have return'd, like $o
many Springs to their wonted extent, up-
on the removal of the Ambient Air that
compre$$'d and bent them: becau$e this,
I $ay, has been doubted, we thought fit
to make this further tryall.
<p>We let down into the Receiver with
the fore-mentioned Bladder two other
much $maller, and of the $ame kinde of
Animal; the one of the$e was not ty'd
up at the neck that there might be liberty
left to the Air that was not $queez'd out
(which might amount to about a fifth
part of what the Bladder held before) to
pa$s out into the Receiver: The other had
the $ides of it $tretch'd out and pre$$'d to-
gether, almo$t into the form of a Cup,
that they might intercept the le$s Air be-
twixt them, and then was $trongly ty'd
<pb n=49>
up at the neck: This done, and the Air
being in $ome mea$ure $uck'd out of the
Pneumatical Gla$s (if I may $o call it)
the Bladder, mention'd at the beginning
of our Experiment, appear'd extended e-
very way to its full Dimen$ions; whereas
neither of the two others did remarkably
$well, and that who$e neck was not ty'd
$eem'd very little, if at all le$s wrinkl'd
then when it was put in.
<p>We made likewi$e a $trong Ligature a-
bout the middle of a long Bladder part-
ly empty'd, and upon the drawing the
Air out of the Receiver, could ob$erve
no $uch $welling betwixt the Ligature and
the Neck of the Bladder, which had been
purpo$ely left open, as betwixt the $ame
Ligature and the bottom of the Bladder,
whence the included Air could no way
get out.
<p>But a further and $ufficient manife$tati-
on whence the intume$$ence of the Blad-
der proceeds, may be deduc'd from the
following Experiment.
<p>TO try then at once both what it was
<MARG><I>Experi-
ment</I> 5.</MARG>
that expanded the Bladder, and what
a powerful Spring there is ev'n in the Air
<pb n=50>
we are wont to think uncompre$$'d, we
cau$'d a Bladder dry, well ty'd and blown
moderately full, to be hung in the Recei-
ver by one end of a $tring, who$e other
end was fa$tned to the in$ide of the Co-
ver: and upon drawing out the ambient
Air, that pre$$'d on the Bladder; the in-
ternal Air not finding the wonted re$i$t-
ance, fir$t $well'd and di$tended the Blad-
der, and then broke it, with $o wide and
crooked a rent, as if it had been forcibly
torn a$$under with hands. After which a
$econd Bladder being convey'd in, the Ex-
periment was repeated with like $ucce$s:
And I $uppo$e it will not be imagin'd that
in this ca$e the Bladder was broken by its
own Fibres, rather then by the Impri-
$on'd Air.
<p>And of this Experiment the$e two <I>Ph&aelig;-
nomena</I> may be taken notice of: The one,
that the Bladder at its breaking gave a
great report, almo$t like a Craker: And
the other, That the Air contain'd in the
Bladder, had the power to break it with
the mention'd Impetuo$ity, long before
the ambient Air was, all or near all, drawn
out of the Receiver.
<p>But, to verifie what we $ay in another
Di$cour$e, where we $how, That even
<pb n=51>
true Experiments may, by rea$on of
the ea$ie mi$take of $ome unheeded
Circum$tance, be un$ucce$sfully try'd;
we will Adverti$e, on this occa$ion,
that we did oftentimes in vain try the
breaking of Bladders, after the manner
above-mention'd: Of which the cau$e
appear'd to be this, That the Bladders we
could not break, having been brought us
ready blown from tho$e that $old them,
were grown dry before they came to our
hands: whence it came to pa$s, that, if
we afterwards ty'd them very hard, they
were apt to fret and $o become un$ervice-
able; and if we ty'd them but moderate-
ly hard, their $tiffne$s kept them from be-
ing clo$'d $o exactly, but that when the
included Air had in the exhau$ted Recei-
ver di$tended them as much as ea$ily it
could, it would in part get out between
the little wrinkles of the Sphincter of the
Neck: Whence al$o it u$ually happen'd,
that, upon the letting in the Air from
without, the Bladders appear'd more flac-
cid and empty then before they were put
in; whereas when the Bladders were
brought us moi$t from the Butchers, we
could, without injuring them, tye their
necks $o clo$e, that none of the Air once
<pb n=52>
blown in, could get out of them, but by
violently breaking them.
<p>It will not be ami$s on this occa$ion to
point at $omething which may de$erve a
more deliberate Speculation then we can
now afford it; namely that the Ela$tical
Power of the $ame Quantity of Air may
be as well Encrea$'d by the Agitation of
the A&euml;rial Particles (whether onely mo-
ving them more $wiftly and $cattering
them, or al$o extending or $tretching
them out, I determine not) within an
every way inclo$ing and yet yielding Bo-
dy; as Di$play'd by the withdrawing of
the Air that pre$$'d it without. For we
found that a Bladder, but moderately
fill'd with Air and $trongly ty'd, being
a while held near the Fire, not onely grew
exceeding turgid and hard, but after-
wards, being approach'd nearer to the
Fire, $uddenly broke with $o loud and ve-
hement a noi$e, as $tony'd tho$e that were
by, and made us, for a while after, almo$t
deaf.
<p>HAving thus $een that the Air has an
<MARG><I>Experi-
ment</I> 6.</MARG>
Ela$tical Power, we were next de$i-
rous to know in $ome mea$ure how far a
<pb n=53>
parcel of Air might by this its own Spring
be dilated. And though we were not pro-
vided of In$truments fit to mea$ure the
dilatation of the Air any thing accurately,
yet becau$e an imperfect mea$ure of it was
more de$ireable then none at all, we de-
vi$'d the following Method as very ea$ily
practicable.
<p>We took a limber Lambs Bladder
which was thorowly wetted in fair Water,
that the $ides of it being $queez'd roge-
ther, there might be no Air left in its
folds: (as indeed we could not afterwards
upon tryal di$cern any) The neck of this
Bladder was $trongly tyed about that of
a $mall Gla$s, (capable of holding five
full drachmes of Water) the Bladder be-
ing fir$t $o compre$$'d, that all the inclu-
ded Air was onely in the Gla$s, without
being pre$$'d there; then the Pump be-
ing $et awork after a few ex$uctions, the
Air in the little Viol began to dilate it
$elf and produce a $mall Tumor in the
Neck of the Bladder; and as the ambi-
ent Air was more and more drawn away,
$o the included Air penetrated further and
further into the Bladder, and by degrees
lifted up the $ides and di$play'd its folds,
till at length it $eem'd to have blown it
<pb n=54>
up to its full extent: whereupon the ex-
ternal Air, being permitted to flow back
into the Reciver, repul$'d the Air that
had fill'd the Bladder into its former nar-
row receptacle, and brought the Bladder
to be again flaccid and wrinkled as before:
Then taking out the Bladder, but with-
out $evering it from the Gla$s, we did by
a hole made at the top of the Bladder fill
the Ve$$el they both made up with Wa-
ter, who$e weight was five Ounces five
Drachmes and an half: Five Drachmes
whereof were above-mention'd to be the
contents of the Bottle. So that in this Ex-
periment, when the Air had mo$t extend-
ed the Bladder, it po$$e$$'d in all above
nine times as much room as it did when it
was put into the Receiver. And it would
probably have much inlarg'd its bounds,
but that the Bladder by its weight and the
$ticking together of its $ides did $ome-
what re$i$t its expan$ion: And which was
more con$iderable, the Bladder appear'd
tumid enough, whil$t yet a pretty deal of
Air was left in the Receiver, who$e ex-
$uction would, according to our former
Ob$ervation, probably have given way
to a further expan$ion of the Air, e$peci-
<pb n=55>
ally $uppo$ing the dilatation not to be re-
$train'd by the Bladder.
<p>SInce we wrote the other day the former
Experiment, we have met with $ome
Gla$$es not very unfit for our purpo$e;
by means of which we are now able, with
a little more trouble, to mea$ure the ex-
pan$ion of the Air a great deal more ac-
curately then we could by the help of the
above-mention'd Bladder, which was
much to narrow to allow the Air its ut-
mo$t di$tention.
<p>We took then fir$t a Cylindrical Pipe
of Gla$s, who$e bore was about a quarter
of an Inch in Diameter: this Pipe was $o
bent and doubled, that, notwith$tanding
its being about two foot in length, it
might have been $hut up into a $mall Re-
ceiver, not a Foot high: But by mi$-
fortune it crack'd in the cooling, whereby
we were reduced to make u$e of one part
which was $traight and intire, but exceed-
ed not $ix or $even Inches. This little
Tube was open at one end; and at the
other, where it was Hermetically $eal'd,
had a $mall Gla$s bubble to receive the
Air who$e dilatation was to be mea$ur'd.
<pb n=56>
<p>Along the $ide of this Tube was pa$t-
ed a $traight narrow piece of Parchment,
divided into twenty $ix equal parts, mark-
ed with black Lines and Figures, that by
them might be mea$ur'd both the inclu-
ded Air and its dilatation. Afterwards
we fill'd the Tube with Water almo$t to
the top, and $topping the open end with
a Finger, and inverting the Tube, the
Air was permitted to a$cend to the above-
mention'd Gla$s bubble. And by rea-
$on this a$cent was very $low, it gave us
the opportunity to mark how much more
or le$s then one of the twenty $ix divi$i-
ons this Air took up. By this means, af-
ter a tryal or two, we were inabled to con-
vey to the top of the Gla$s a bubble of
Air equal enough, as to $ight, to one
of tho$e Divi$ions: Then the open end
of the Tube being put into a $mall Viol,
who$e bottom was cover'd with Water
about half an Inch high; we included
both Gla$$es into a $mall and $lender Re-
ceiver, and cau$ed the Pump to be $et a-
work. The event was, That at the fir$t
ex$uction of the Air there appear'd not
any expan$ion of the bubble, comparable
to what appear'd at the $econd, and that
upon a very few ex$uctions the bubble
<pb n=57>
reaching as low as the $urface of the $ub-
jacent Water, gave us cau$e to think
that if our Pipe had not been broken it
would have expanded it $elf much fur-
ther: Wherefore we took out the little
Tube, and found that be$ides the twenty
$ix divi$ions formerly mention'd, the
Gla$s bubble and $ome part of the Pipe
to which the divided Parchment did not
reach, amounted to $ix divi$ions more.
Whereby it appears that the air had taken
up one and thirty times as much room as
before, and yet $eem'd capable of a much
greater expan$ion, if the Gla$s would
have permitted it. Wherefore, after the
former manner, we let in another bubble,
that by our gue$s was but half as big as
the former, and found, that upon the ex-
$uction of the Air from the Receiver, this
little bubble did not onely fill up the
whole Tube, but (in part) break through
the $ubjacent Water in the Viol, and
thereby manife$t it $elf to have po$$e$$ed
$ixty and odde times its former room.
<p>The$e two Experiments are mention'd
to make way for the more ea$ie belief of
that which is now to follow. Finding
then that our Tube was too $hort to $erve
our turn, we took a $lender Quill of Gla$s
<pb n=58>
which happen'd to be at hand, though it
were not $o fit for our purpo$e as we
could have wi$hed, in regard it was three
or four times as big at one end as the o-
ther. This Pipe which was thirty Inches
long, being Hermetically $eal'd at the
$lender end, was almo$t filled with Wa-
ter; and after the above-related manner
a bubble was convey'd to the top of it,
and the open extream was put into a Viol
that had a little fair Water at the bottom:
Then the Cover, by means of a $mall hole
purpo$ely made in it for the Gla$s Pipe to
$tand out at, was cemented on to the Re-
ceiver, and the Pump being $et awork,
after $ome ex$uctions, not onely the Air
manife$tly appear'd extended below the
$urface of the $ubjacent Water; but one
of the By-$tanders affirms, that he $aw
$ome bubbles come out at the bottom of
the Pipe and break through the Water
This done, we left off Pumping, and ob-
$erv'd how at the unperceiv'd leaks of the
Receiver the Air got in $o fa$t, thatit
very quickly impell'd up the Water to
the top of the Tube, excepting a little
$pace whereinto that bubble was repul$'d,
which had $o lately po$$e$$'d the whole
Tube; this Air at the $lender end ap-
<pb n=59>
pear'd to be a Cylinder of 5/6 parts of an
Inch in length; but when the Pipe was
taken out and turn'd up$ide down, it ap-
pear'd at the other end inferior in bulk to a
Pea.
<p>The$e things being thus done we took
(to make the Experiment the more ex-
actly) a $mall pair of Scales, $uch as Gold-
Smiths u$e to weigh Gold Coyn in; and
weighing the Tube and Water in it, we
found them to amount to one Ounce thir-
ty Grains and an half: Then we pour'd in
as much Water as $erv'd to fill up the
Tube, wherein before we had left as much
$pace unfill'd up as was po$$e$$'d by the
bubble; and weighing again the Pipe and
Water, we found the weight increa$'d
onely by one Grain. La$tly, pouring out
the Water, and carefully freeing the Pipe
from it (which yet we could not perfectly
doe) we weighed the Gla$s alone, and
found it to want two Drachmes and thirty
two Grains of its former weight: So
that the bubble of Air taking up the room
but of one Grain in weight of Water, it
appear'd that the Air by its own <G>e)lith\r</G>
was $o rarified, as to take up one hundred
fifty two times as much room as it did be-
fore: though it were then compre$$'d by
<pb n=60>
nothing but the ordinary pre$$ure of the
contiguous Air. I know not whether it
be requi$ite to take notice, that this Ex-
periment was made indeed in a moi$t
Night, but in a Room, in who$e Chim-
ney there was burning a good Fire, which
did perhaps $omewhat rarifie the Air of
which the bubble con$i$ted.
<p>It has $eem'd almo$t incredible which is
related by the Indu$trious <I>Mer$ennus,</I> That
the Air by the violence of heat, though
as great as our Ve$$els can $upport with-
out fu$ion, can be $o dilated as to take up
$eventy times as much room as before:
Wherefore becau$e we were willing to
have a confirmation of $o $trange a <I>Ph&aelig;no-
menon;</I> we once more convey'd into the
Tube a bubble of the bigne$s of the for-
mer, and pro$ecuting the Experiment as
before with the $ame Water, we ob$erved
that the Air did manife$tly $tretch it $elf
$o far, as to appear $everal times a good
way below the $urface of the Water in the
Viol, and that too with a $urface very
convex toward the bottom of the Pipe.
Nay, the Pump being ply'd a little lon-
ger, the Air did manife$tly reach to that
place where the bottom of the Tube
lean'd upon the bottom of the Viol, and
<pb n=61>
$eem'd to knock upon it and rebound
from it: Which Circum$tances we adde,
partly that the <I>Ph&aelig;nomenon</I> we have been
relating may not be imputed to the
bare $ub$iding of the Water that fill'd
the Tube, upon the taking off the pre$-
$ure of the ambient Air. And partly al-
$o that it may appear that if our Expe-
riments have not been as accurately made
as with fitter In$truments might perhaps
be po$$ible; yet the expan$ion of the
Air is likely to be rather greater then
le$$er then we have made it: Since the
Air was able to pre$s away the Water at
the bottom of the Pipe, though that were
about two Inches below the $urface of the
Water that was then in the Viol, and
would have been at lea$t as high in the
Pipe, if the Water had onely $ub$ided and
not been depre$$ed: So that it $eems not
unlikely that if the Experiment could be
$o made, as that the expan$ion of the Air
might not be re$i$ted by the Neighboring
Bodies, it would yet inlarge its bounds,
and perhaps $tretch it $elf to two hundred
times its former bulk, if not more. How-
ever, what we have now try'd will, I hope,
$uffice to hinder divers of the <I>Ph&aelig;nomena</I>
of our Engine from being di$tru$ted:
<pb n=62>
Since in that part of the Atmo$phere we
live in, that which we call the free Air (and
pre$ume to be $o uncompre$$'d) is crouded
into $o very $mall a part of that $pace,
which if it were not hindred it would po$-
$e$s. We would gladly have tryed al$o
whether the Air at its greate$t expan$ion
could be further rarified by heat; but do
what we could, our Receiver leak'd too
fa$t to let us give our $elves any $atisfacti-
on in that particular.
<p>TO di$cover likewi$e by the means of
<MARG><I>Experi-
ment</I> 7.</MARG>
that pre$$ure of the Air, both the
$trength of Gla$s, and how much inte-
re$t the Figure of a Body may have in its
greater or le$$er Re$i$tance to the pre$$ure
of other Bodys, we made the$e further
tryals.
<p>We cau$'d to be blown with a Lamp a
round Gla$s bubble, capable of contain-
ing, by gue$s, about five Ounces of Wa-
ter, with a $lender neck about the bigne$s
of a Swans Quill, and it was purpo$ely
blown very thin, as Viols made with
Lamps are wont to be, that the thinne$s
of the matter might keep the roundne$s
of the Figure from making the Ve$$el too
<pb n=63>
$trong. Then having moderately empty-
ed the Receiver, and taken it out of the
Pump, we $peedily applyed to the Ori-
fice of the bottom of it the Neck of the
newly mention'd Gla$s, carefully $topping
the Crannys with melted Plai$ter, that no
Air might get in at them: And after
turning the Key of the Stop-cock, we
made a free pa$$age for the Air to pa$s out
of the bubble into the Receiver: which it
did with great celerity, leaving the bub-
ble as empty as the Receiver it $elf; as ap-
pear'd to us by $ome Circum$tances not
now to be in$i$ted on. Notwith$tanding
all which, the Ve$$el, continuing as intire
as before, gave us cau$e to wonder that
the bare Roundne$s of the Figure $hould
inable a Gla$s, almo$t as thin as Paper, to
re$i$t $o great a pre$$ure as that of the
whole incumbent Atmo$phere. And ha-
ving reiterated the Experiment, we found
again that the pre$$ure of the ambient
Body, thru$ting all the parts inwards,
made them, by rea$on of their arched Fi-
gure, $o $upport one another, that the
Gla$s remain'd as whole as at fir$t.
<p>Now that the Figure of the Gla$s is
of great moment in this matter, may be
evinced by this other Experiment.
<pb n=64>
<p>WE took a Gla$s Helmet or Alem-
<MARG><I>Experi-
ment</I> 8.</MARG>
bick (delineated by the $eventh
Figure) $uch as Chymi$ts u$e in Di$tilla-
tions, and containing by conjecture be-
tween two and three Pints: The <I>Ro$trum</I>
or No$e of it mark'd with <I>(c)</I> was Herme-
tically clo$ed; and at the top of it was a
hole, into which was fitted and cemented
one of the Shanks of a middle-$iz'd Stop-
cock; $o that the Gla$s being turn'd up-
$ide-down, the wide Orifice (which in
common Gla$s-Helmets is the onely one)
was upwards; and to that wide Orifice
was fitted a ca$t-Cover of Lead, which
was carefully cemented on to the Gla$s:
Then the other Shank of the Stop-cock
being with Cement likewi$e fa$ten'd into
the upper part of the Pump, the ex$ucti-
on of the Air was endeavoured. But it
was not long before, the remaining Air
being made much too weak to ballance
the pre$$ure of the ambient Air, the Gla$s
was not without a great noi$e crack'd al-
mo$t half round, along that part of it
where it began to bend inwards: As if
in the Figure the crack had been made ac-
cording to the Line <I>(ab);</I> and upon an
<pb n=65>
endeavour to pump out more of the Air,
the crack once began, appear'd to run on
further; though the Gla$s where it was
broken $eem'd to be by conjecture above
ten, $ome thought above twenty times as
thick as the bubble mention'd in the fore-
going Experiment.
<p>This will perhaps make it $eem $trange,
that having taken another Gla$s bubble
blown at the $ame time, and like for
ought we di$cern'd for $ize, thickne$s
and Figure to that thin one formerly
mention'd; and having $eal'd it up Her-
metically, and $u$pended it in the Recei-
ver, the ex$uction of the ambient Air did
not enable the impri$oned Air to break, or
in the lea$t to crack the bubble; though
the Experiment were laboriou$ly try'd,
and that $everal times with bubbles of o-
ther $izes: But that perhaps the heat of
the Candle or Lamp wherewith $uch
Gla$$es are Hermetically $eal'd, (not to
mention the warmth of his hands that
$eal'd it) might $o rarifie the contained
Air, as much to weaken its Spring, may
$eem probable by the following Expe-
riments.
<pb n=66>
<p>WE took a Gla$s Viol able to hold
<MARG><I>Experi-
ment</I> 9.</MARG>
three or four Ounces of Water,
and of the thickne$s u$ual in Gla$$es of
that $ize; into the Neck of this was put
a moderately $lender Pipe of Gla$s, which
was carefully fa$ten'd with a mixture of e-
qual parts of Pitch and Ro$in to the Neck
of the Viol, and which reach'd almo$t to
the bottom of it, as the $ixth Figure de-
clares.
<p>This Viol being upon a particular de-
$ign fill'd with Water, till that came up in
it a pretty deal higher then the lower end
of the Pipe, was put into one of our $mall
Receivers, (containing between a Pint
and a Quart) in $uch manner as that the
Gla$s Pipe, pa$$ing through a hole made
purpo$ely for it in the Leaden-Cover of
the Receiver, was for the mo$t part of it
without the Ve$$el, which being exactly
clo$ed, the Pump was $et awork: But at
the very fir$t ex$uction, and before the
Sucker was drawn to the bottom of the
Cylinder, there flew out of the Viol a
piece of Gla$s half as broad as the Palm
of a Mans Hand, and it was thrown out
with $uch violence, that hitting again$t
<pb n=67>
the Neighboring $ide of the Receiver, it
not onely dafh'd it $elf to pieces, but
crack'd the very Receiver in many places,
with a great noi$e that much $urpri$ed all
that were in the Room. But it $eem'd
that in $o little a Receiver, the Air about
the Viol being $uddenly drawn out, the
Air Impri$on'd in the Ve$$el, having on
it the whole pre$$ure of the Atmo$phere
(to which by the Pipe open at both ends,
It and the Water were expo$'d) and not
having on the other $ide the wonted pre$-
$ure of the Ambient Air to ballance that
other pre$$ure, the re$i$tance of the Gla$s
was finally $urmounted, and the Viol once
beginning to break where it was weake$t,
the external Air might ru$h in with vio-
lence enough to throw the crack'd parcel
$o forcibly again$t the Neighboring $ide
of the Receiver, as to break that too.
<p>And this may be pre$umed $ufficient to
verifie what we delivered in that part of
our Appendix to the fir$t Experiment,
where we mention'd the almo$t equal
pre$$ure of the Air on either $ide of a
thin Gla$s Ve$$el, as the cau$e of its not
being broken by the forcible Spring of
the contain'd Air. But yet that it be not
$u$pected that chance had an intere$t in $o
<pb n=68>
odde an Experiment as we have been Re-
lating, we will adde that for farther $ati$-
faction we reiterated it in a round Gla$$e
containing by gue$$e about $ix ounces
of water: this violl we put into $uch a
$mall Receiver as was lately mention'd,
in $uch manner as that the bottome of
it re$ted upon the lower part of the Pneu-
maticall Gla$$e, and the Neck came out
through the Leaden-Cover of the $ame
at a hole made purpo$ely for it. But be-
ing made circum$pect by the foregoing
mi$chance, we had put the violl into a
Bladder, before we put it into the Re-
ceiver to hinder this la$t named Gla$$e
from being endanger'd by the breaking
of the other. Then the Pneumaticall
ve$$ell being clos'd $o that no way was
left for the outward Air to get into it,
but by breaking through the Viol, into
who$e cavity it had free acce$$e by the
mouth of it, (which was purpo$ely left
open,) the Sucker being nimbly drawn
down, the external Air immediatly pre$$'d
forcibly as well upon the Leaden-Co-
ver as the Violl; and the Cover hap-
pening to be in one place a little narrow-
er then the edge of the Pneumatical Gla$s,
was depre$$'d, and thru$t into it $o vio-
<pb n=69>
lently by the incumbent Air, that get-
ting a little within the tapering Lip of the
Gla$s, it did like a kinde of Wedge, thru$t
out that $ide where it was depre$$'d, $o as,
though the Receiver was new, to $plit it.
This accident being thus mention'd upon
the by to confirm what we formerly $aid
touching the fitne$s or unfitne$s of Gla$$es
of $ome Figures to re$i$t the pre$$ure of
the Atmo$phere; We will proceed to
relate the remaining part of the Experi-
ment, namely, That having fitted on a
wider Cover to the $ame Receiver, and
clo$ed both that and the crack with Ce-
ment, we pro$ecuted the Experiment in
the manner above related, with this $uc-
ce$s: That upon the quick depre$$ing of
the Sucker, the external Air bur$t the
Body of the Viol in above a hundred pie-
ces, many of them exceeding $mall, and
that with $uch violence that we found a
wide rent, be$ides many holes, made in
the Bladder it $elf.
<p>And to evince that the$e <I>Ph&aelig;nomena</I>
were the effects of a limited and even
moderate force, and not of $uch an ab-
horrency of a <I>Vacuum</I> as that to avoid it,
many have been plea$ed to think that Na-
ture mu$t, upon occa$ion, exerci$e an al-
<pb n=70>
mo$t boundle$s power; we afterwards pur-
po$ely try'd this Experiment with $everal
Gla$$es $omewhat thicker then tho$e Vi-
ols, and found the event to verifie our con-
jecture, that it would not $ucceed: for
the Gla$$es were taken out as intire as they
were put in.
<p>And here, My Lord, I hold it not un-
fit, upon occa$ion of the mention that
has been made of our having employ'd
$mall Receivers, and one of them, not-
with$tanding its being crack'd, to annex
the$e two Adverti$ements.
<p>Fir$t then, be$ides the great Pneuma-
tical Gla$s $o often mention'd, and the
proportionate Stop-cock, we thought fit
to provide our $elves of $ome $mall Recei-
vers blown of Cry$talline Gla$s, of $eve-
rall Shapes, and furni$hed with $maller
Stop-cocks purpo$ely made; and this we
did upon hopes that when we had $ur-
mounted the difficulties to be met with in
Cementing the Gla$$es to the Stop-
cocks, and the Pneumatical Ve$$els to the
Pump $o exqui$itely as is requi$ite for our
purpo$e, we $hould from the $malne$s of
our Receivers receive a four-fold Advan-
tage. The fir$t, that by rea$on of the
$lenderne$s of the Ve$$els, and their be-
<pb n=71>
ing made of much purer and clearer me-
tall, as the Gla$s-men $peak, then the
great Receiver, we might have a more
perfect view of every thing happening
within them. The next, that $uch $mall
Ve$$els might be empty'd with le$s la-
bour and in much le$$e time. The third,
that this nimble ex$uction of the ambient
Air would make many changes in the
Bodies $hut up in the$e gla$$es more $ud-
den and con$picuous then otherwi$e they
would prove. And the la$t, that we $hould
be able to draw and keep out the Air much
more perfectly from $uch $mall Ve$$els
then from our large Receiver. But though
we were not much di$-appointed in the
expectation of the three fir$t advantages,
yet we were in our hopes of the fourth.
For be$ides the great difficulty we found
in fitting together the Gla$$es, the Stop-
cocks and the Covers; be$ides this I $ay,
we found our $elves $eldom able to draw,
and keep out the Air $o far as to make the
remaining Air in the$e Receivers weaker
then the remaining Air in our great Recei-
ver. For though $ometimes the Leaks
of $ome of the$e little Receivers may be
much either fewer or $maller then tho$e
of the larger Ve$$el; yet a little Air get-
<pb n=72>
ting into one of the$e, wherein it had but
little room to expand and di$play it $elf,
might pre$s as much upon all parts of the
internal $urface of the Ve$$el, and upon
the included Bodies, as a greater quan-
tity of Air in a Ve$$el in who$e capacity
it might finde more room to expand it
$elf.
<p>The other thing that we were to ad-
verti$e, is, That 'tis not every $mall crack
that can make $uch a Receiver as is of a
roundi$h Figure altogether u$ele$s to our
Experiment, in regard that upon the ex-
$uction of the internal Air, the ambient
Air on all $ides pre$$ing the Gla$s inwards
or towards the middle, does con$equent-
ly thru$t the Lips of the crack clo$er, and
$o rather clo$e then increa$e it.
<p>This I mention partly becau$e Recei-
vers fit for our turn are more ea$ily
crack'd then procur'd, and therefore ought
not to be unnece$$arily thrown away as
un$erviceable: And partly becau$e I think
it becomes one that profe$$es him$elf a
faithful Relator of Experiments, not to
conceal from Your Lord$hip, that after a
few of the foregoing Experiments were
made, there happen'd in the great Recei-
ver a crack of about a Span long, begin-
<pb n=73>
ning at the upper Orifice, and occa$ion'd,
as it $eem'd, by the exce$$ive heat of too
large an Iron that was employ'd to melt
the Cement about that Orifice. But ha-
ving laid upon this crack a broad Plai$ter,
which in one of our E$$ays written $ome
years $ince to your ingenious and hopeful
Cou$in <I>Fones,</I> we extoll for the mending
of crack'd Receivers, and other Chymi-
cal Gla$$es; and having afterwards thick-
ly over-laid this Plai$ter with Diachylon,
we neither could then, nor can yet per-
ceive that the Ve$$el leaks $en$ibly at that
crack.
<p>The Plai$ter was made of good quick
Lime finely poudred, and nimbly ground
with a Pe$tle in a Morter, with a quantity
(I know not how much preci$ely, not ha-
ving tho$e E$$ays in this place) of $cra-
pings of Chee$e and a little fair Water,
no more then is ju$t nece$$ary to bring the
mixture to a $omewhat $oft Pa$te, which
when the Ingredients are exqui$itely in-
corporated, will have a $trong and
$tincking $mell: Then it mu$t be im-
mediately $pread upon a Linnen Cloath
three or four fingers breadth, and pre$ently
apply'd, le$t it begin to harden. But if
Your Lord$hip had $een how we mended
<pb n=74>
with it Receivers even for the mo$t $ub-
tle Chymical Spirits, You would $carce
wonder at the $ervice it has done in our
Pneumatical Gla$s.
<p>WE took a Tallow-Candle of $uch
<MARG><I>Experi-
ment</I> 10.</MARG>
a $ize that eight of them make
about a pound, and having in a very com-
modious Candle$tick let it down into the
Receiver, and $o $u$pended it that the
Flame burnt almo$t in the middle of the
Ve$$el, we did in $ome two minutes ex-
actly clo$e it up: and, upon Pumping ve-
ry nimbly, we found that within little
more then half a minute after the Flame
went out, though the Snuff had been
purpo$ely left of that length we judged
the mo$t convenient for the la$ting of
the Flame.
<p>But the $econd time having put in the
$ame Candle into the Receiver, (after it
had by the bla$ts of a pair of Bellows
been freed from Fumes) the Flame la$ted
about two minutes from the time the
Pumper began to draw out the Air; up-
on the fir$t ex$uction whereof, the Flame
$eem'd to contract it $elf in all its Dimen-
$ions. And the$e things were further ob-
<pb n=75>
$ervable, that after the two or three fir$t
ex$uctions of the Air, the Flame (except
at the very top) appear'd exceeding blew,
and that the Flame $till receded more and
more from the Tallow, till at length it
appear'd to po$$e$s onely the very top of
the Week, and there it went out.
<p>The $ame Candle being lighted again
was $hut into the Receiver, to try how it
would la$t there without drawing forth
the Air, and we found that it la$ted much
longer then formerly; and before it went
out receded from the Tallow towards the
the top of the Week, but not near $o
much as in the former Experiment.
<p>And having an intention to ob$erve par-
ticularly what the motion of the $moak
would be in the$e Experiments: We
took notice that when the Air was not
drawn out, there did upon the extinction
of the Flame a con$iderable part of the
Week remain kindled, which (probably
by rea$on of the Circulation of the Air
in the Ve$$el, occa$ion'd by the heat) e-
mitted a Steam, which a$cended $wiftly
and directly upwards in a $lender and unin-
terrupted Cylinder of $moke, till it came
to the top, whence it manife$tly recoyl'd
by the $ides to the lower part of the Ve$-
<pb n=76>
$el. Whereas when the Flame went out
upon the ex$uction of the Air one time
(when the Flame retir'd very lea$urely
to the top) we perceived it not to be fol-
low'd by any $moke at all. And at an
other time the upper part of the Week
remaining kindled after the extinction
of the Flame, the $lender $team of Fumes
that did ari$e a$cended but a very little
way, and then after $ome uncertain mo-
tions this and that way, did, for the mo$t
part, $oon fall downwards.
<p>Being de$irous al$o to try whether
there would be any difference as well in
our Receiver as there is wont to be el$e-
where betwixt Candles made of Wax and
tho$e made of Tallow, as to their dura-
tion; we took $lender Tapers of white
Wax, (commonly called Virgins Wax)
that being found to burn with much le$s
$moke then common yellow Wax: Six
of the$e of like bigne$s, and each of them
of about the thickne$s of a Swans Quill,
we pre$$'d together into one Candle: And
having lighted all the Weeks, we let in
the above-mention'd Wax into the Re-
ceiver, and made what ha$te we could to
clo$e it up with Cement. But though in
the mean while we left open the Valve
<pb n=77>
of the Cylinder, the hole of the Stop-
cock and that in the Cover of the Re-
ceiver, that $ome Air might get in to
cheri$h the Flame and the $moke might
have a vent; Yet for $o great a Flame
the Air $ufficed not $o much as till the
Cover could be perfectly luted on: So
that before we were quite ready to imploy
the Pump, the Candle was extingui$hed.
Wherefore we took but one of the a-
bove mention'd Tapers, and having
lighted it, clo$'d it up in the Receiver, to
try how long a $mall Flame with a pro-
portionable $moke would continue in
$uch a quantity of Air: But we found
upon two $everal tryals, that from the
beginning of pumping, the Flame went
out in about a minute of an hour. It
appear'd indeed to us that the $winging
of the Wier to and fro (in the Engine
$haken by pumping) ha$ten'd the vani$h-
ing of the Flame, which $eem'd by that
motion to be ca$t $ometimes on one $ide
of the Week and $ometimes on the o-
ther; But though once we purpo$ely
refrain'd pumping after a very few ex-
$uctions of the Air, that the Flame might
not be agitated, yet it la$ted not much
longer then the newly mention'd time.
<pb n=78>
And la$tly, clo$ing up the $ame Taper,
lighted again, to di$cover how long it
would la$t without drawing out of the
Air, we found that it burn'd for a while
vividly enough, but afterwards began to
be le$$en'd more and more in all its Di-
men$ions. And we ob$erv'd that the
Flame did not, as before, retire it $elf by
little and little towards the top, but to-
wards the bottom of the Week (from
which yet it did a little withdraw upwards
ju$t before it went out) $o that the upper
part of the Week appear'd for a pretty
while manife$tly above the top of the
Flame, which having la$ted about five
minutes, was $ucceeded by a directly a$-
cending $tream of Smoak.
<p>THere was taken a Wier, which being
<MARG><I>Experi-
ment</I> 11.</MARG>
bent almo$t in the form of a Screw,
con$tituted $uch an In$trument to contein
Coals and leave them every way acce$$i-
ble to the Air, as the tenth Figure de-
clares; the breadth of this Ve$$el was no
le$s then that it might with ea$e be con-
vey'd into the Receiver: And having filld
it to the height of about five Inches with
throughly kindled Wood-coals, we let
<pb n=79>
it down into the Gla$s; and $peedily clo-
$ing it, we cau$'d the Pumper to ply
his work, and ob$erv'd that upon the ve-
ry fir$t ex$uction of the Air (though per-
haps not becau$e of that onely) the Fire
in the Coals began to grow very dim, and
though the agitation of the Ve$$el did
make them $wing up and down (which in
the free Air would have retarded the ex-
tinction of the Fire) yet when we could
no longer di$cern any redne$s at all in any
of them; ca$ting our eyes upon a Minute-
Watch we kept by us on this occa$ion, we
found that from the beginning of the
Pumping (which might be about two mi-
nutes after the Coals had been put in
glowing) to the total di$-appearing of
the Fire, there had pa$$ed but three mi-
nutes.
<p>Whereupon, to try the Experiment a
little further, we pre$ently took out the
Coals, in which it $eems there had re-
mained $ome little parcels of Fire, rather
cover'd then totally quench'd: For in the
open Air the Coals began to be re-kind-
led in $everal places, wherefore having by
$winging them about in the Wier,
throughly lighted them the $econd time,
welet them down again into the Receiver,
<pb n=80>
and clo$'d it $peedily as before; and then
waiting till the Fire $eem'd totally ex-
tinct without medling with the Pump, we
found that from the time the Ve$$el was
clo$'d till that no Fire at all could be per-
ceiv'd there had pa$$ed about four mi-
nutes: Whereby it $eem'd to appear that
the drawing away of the ambient Air
made the Fire go out $ooner then other-
wi$e it would have done; though that part
of the Air that we drew out left the more
room for the $tifling $teams of the Coals
to be received into.
<p>La$tly, Having taken out the Wier
and put other Coals into it, we did, in the
$ame Room where the Engine $tood, let it
hang quietly by a $tring in the open Air,
to try how long the Fire would la$t with-
out agitation when no Air was kept from
it. And we found that the Fire began to
go out fir$t at the top and out-$ides of the
Coals; but inwards and near the bottom
the Fire continu'd vi$ible for above half
an hour, a great part of the Coals, e$pe-
cially tho$e next the bottom, being burnt
to a$hes before the Fire went out.
<p>We cau$'d likewi$e a piece of Iron to
be forg'd, of the bigne$s of a middle $iz'd
Char-coal, and having made it red hot
<pb n=81>
throughout; we cau$'d it in the lately
mention'd Wier, to be $peedily convey'd
and $hut up into the Receiver, being de-
$irous to try what would become of a
glowing Body, by rea$on of its texture
more vehemently hot then a burning
Coal of the $ame bigne$s, &amp; yet unlike to
$end forth $uch copious &amp; $tifling Fumes:
But we could not ob$erve any manife$t
change upon the ex$uction of the Air.
The Iron began indeed to lo$e its Fiery
redne$s at the top, but that $eem'd to be
becau$e it was it the upper end $omewhat
more $lender then at the lower: The red-
ne$s, though it were in the day time, con-
tinued vi$ible about four minutes; and
then, before it did quite di$-appear, we
turn'd the Key of the Stop-cock but
could not di$cern any change of the Iron
upon the ru$hing in of the Air. Yet $ome
little remainders of Wax that $tuck to
the Wier, and were turn'd into Fumes by
the heat of the neighboring Iron, $eem'd
to afford a more plentiful, or at lea$t a
much more free expanded $moke when
the Air was $uck'd out, then afterwards;
though allowance was made for the de-
crea$ing heat of the Iron. And la$tly,
notwith$tanding a con$iderable ex$uction
<pb n=82>
of the ambient Air, though not by far $o
great a one as might have been made by
the Engine; and notwith$tanding the in-
con$iderable di$$ipation of the parts of the
Iron, the $urrounding $ides of the Recei-
ver were $en$ibly, and almo$t offen$ively
heated by it; in$omuch that a pretty while
after the Iron was taken out, the $ides of
the Gla$s manife$tly retain'd a warmth:
which would not be unfit to be con$ider'd
by a Per$on at more lea$ure then I am
now.
<p>BEing willing to try after this $ome-
<MARG><I>Experi-
ment</I> 12.</MARG>
thing that would not cheri$h much
Fire at once, and would keep Fire much
longer then a Coal. We took a piece of
Match, $uch as Souldiers u$e, of the thick-
ne$s of a Mans little Finger, or $omewhat
thicker; and this being well lighted at
one end, was by a $tring $u$pended with
that end downwards in the cavity of the
Receiver which was immediately clo$'d:
And yet by that time it could well be $o,
the copious Fumes of the Match had neer
fill'd and darken'd the Receiver. Where-
fore, le$t the Ve$$el $hould be endanger'd,
the Pump was nimbly ply'd, and a great
<pb n=83>
deal of Air and Smoke mixt together was
drawn out, whereby the Receiver grow-
ing more clear, we could di$cern the Fire
in the Match to burn more and more lan-
guidly: And notwith$tanding that by the
diligence u$'d in Pumping, it $eem'd to
have room enough allow'd it to throw
out Fumes; yet after no long time it
cea$'d from being di$cernable either by its
Light or its Smoke. And though by
that we were invited to $uppo$e it quite
extingui$hed, yet we continu'd pumping
a while, in pro$ecution of another Expe-
riment we were trying at the $ame time:
And this we did the more willingly be-
cau$e of a $u$picion the Experiment a-
bout the Coals might ea$ily $ugge$t, and
which the event declar'd not to have been
altogether groundle$s. For upon the
Admi$$ion of the external Air, the Fire,
that $eem'd to have gone out a pretty
while before, did pre$ently revive; and
being as it were refre$h d by the new Air,
and blown by the Wind made by that
Air in ru$hing in, it began again to $hine
and di$$ipate the neighboring Fuel into
Smoke as formerly.
<pb n=84>
<p>A While after we let down into
<MARG><I>Experi-
ment</I> 13.</MARG>
the Receiver together with a ligh-
ted piece of Match, a great Bladder well
tyed at the Neck, but very lank, as not
containing actually much (if any thing) a-
bove a Pint of Air, but being capable of
containing ten or twelve times as much.
<p>Our $cope in this Experiment was
partly to try whether or no the $moke of
the Match, repleni$hing the Receiver,
would be able to hinder the Dilatation of
the inward Air, upon the ex$uction of the
Ambient. And partly to di$cover whe-
ther the extinction of the Fire in the
Match did proceed from want of Air, or
barely from the pre$$ure of its own
Fumes, which for want of room to ex-
pand them$elves in, might be $uppo$'d
to Recoyl upon the Fire, and $o to
$tifle it.
<p>The event of our tryal was, That
at the beginning of our Pumping the
Match appear'd well lighted, though
it had almo$t fill'd the Receiver with
its plentiful Fumes: But by degrees it
burnt more and more dimly, notwith-
$tanding that by the nimble drawing
<pb n=85>
out the Air and Smoke, the Ve$$el
were made le$s opacous, and le$s full of
compre$$ing matter; as appeard by this,
That the longer we pump'd, the le$$er
Air and Smoke came out of the Cylin-
der at the opening the Valve, and con$e-
quently the le$s came into it before; yet
the Fire in the Match went but $lowly
out. And when afterwards, to $atisfie
our $elves of its expiration, we had dar-
ken'd the Room, and in vain endeavored
to di$cover any $park of Fire, as we could
not for $ome time before by the help of
Candles di$cern the lea$t ri$ing of Smoke,
we yet continued pumping $ix or $even
times; and after all that letting in the
Air, the $eemingly dead Fire quickly
revived, and manife$ted its recovery by
Light and $tore of Smoke, with the
latter of which it quickly began to re-
pleni$h the Receiver. Then we fell
to pumping afre$h, and continued that
labour $o long till the re-kindled
Match went out again: and thinking
it then fit not to cea$e from Pum-
ping $o $oon as before, we found that
in le$s then half a quarter of an hour the
Fire was got out for good and all,
<pb n=86>
and pa$t the po$$ibility of being recover'd
by the re-admitted Air.
<p>Some Circum$tances, be$ides tho$e al-
ready mention'd, occurr'd in the making
of the Experiment, of which the$e are
the principal.
<p>Fir$t, when the Receiver was full of
Smoke, if the Cylinder were emptied,
immediately upon the turning of the
Stop-cock, the Receiver would appear
manife$tly darken'd to his eye that look'd
upon the light through it: and this dark-
ne$s was much le$s when the Receiver was
much le$s fill'd with Fumes: It was al$o
in$tantaneous, and $eem'd to proceed from
a $udden change of place and $cituation
in the exhalations, upon the vent $ud-
denly afforded them and the Air they
were mixt with, out of the Receiver into
the Cylinder.
<p>The next thing we ob$erv'd was, a kinde
of <I>Halo</I> that appear'd a good while about
the Fire, and $eem'd to be produced by
the $urrounding Exhalations.
<p>And la$tly, it is remarkable, That even
when the Fumes $eemed mo$t to reple-
ni$h the Receiver, they did not $en$ibly
hinder the Air included in the Bladder
from dilating it $elf after the $ame manner
<pb n=87>
(for ought we could di$cern) as it would
have otherwi$e done: So that before the
Fire or the Match was quite extinct, the
Bladder appear'd $well'd at lea$t to $ix or
$even times its former capacity.
<p>Since the writing of the$e la$t Lines,
we took a $mall Receiver, capable of
containing (by gue$s) about a pound and
a half of Water; and in the mid$t of it
we $u$pended a lighted Match, but though
within one minute of an hour (or there-
abouts) from the putting in of the Match,
we had cemented on the Cover, yet we
could not make $uch ha$te, but that before
we began to pump, the Smoke had $o
fill'd that $mall Receiver, as for ought we
di$cern'd, to choke the Fire. And having
again and again reiterated the Experi-
ment, it $eem'd $till as at fir$t, that we
could not clo$e up the Ve$$el and pump
out all the Fumes time enough to re$cue
the Fire from Extinction; whereupon we
made u$e of this Expedient. A$$oon as
we had pump'd once or twice, we $udden-
ly turn'd the Key, and thereby gave acce$s
to the excluded Air, which ru$hing vio-
lently in, as if it had been forced thorow
a pair of Bellows, did both drive away
the a$hes, fill the Gla$s with fre$h Air, and
<pb n=88>
by blowing the almo$t extingui$h'd Fire,
re-kindl'd it, as appear'd by the Matches
beginning again to $moke, which before it
had cea$'d to do; we having by this
means obtain'd a lighted Match in the
Receiver, without being reduc'd to $pend
time to clo$e it up, commanded the Air
to be immediatly pump'd out, and found
that upon the ex$uction of it, the Match
quickly left $mokeing, as it $eem'd, by
rea$on of the ab$ence of the Air; and
yet if $ome urgent occa$ions had not hin-
der'd us, we would for greater $ecurity
have try'd, whether or no the Match re-
kindled as formerly, would $moke much
longer, in ca$e of no ex$uction of the am-
bient Air.
<p>TO try diver$e things at once,
<MARG><I>Experi-
ment</I> 14.</MARG>
and particularly whether Fire,
though we found it would not long la$t,
might not yet be produced in our eva-
cuated Receiver: We took a Pi$tol of
about a Foot in length, and having
firmly tyed it to a $tick almo$t as long as
the Cavity of the Receiver, we very
carefully prim'd it with well dry'd Gun-
powder, and then cocking it, we ty'd to
<pb n=89>
the Tricker one end of a $tring, who$e
other end was fa$ten'd to the Key former-
ly mention'd to belong to the Cover of
our Receiver. This done, we convey'd
the Pi$tol, together with the annexed
Staff, into the Ve$$el: which being clo$'d
up, and empty'd after the u$ual man-
ner, we began to turn the Key in the
Cover; and thereby $hortning the $tring
that reach'd from it to the Pi$tol, we
pull'd a$ide the Tricker, and ob$erv'd,
that according to our expectation the
force of the Spring of the Lock was
not $en$ibly abated by the ab$ence of
the Air. (from who$e <I>impetus</I> yet $ome
Modern Naturali$ts would derive the
cau$e of the motion of Re$titution in
$olid Bodies) For the Cock falling
with its wonted violence upon the Steel,
$truck out of it as many and as con$pi-
cuous parts of Fire, as, for ought we
could perceive, it would have done in
the open Air. Repeating this Experi-
ment divers times, we al$o ob$erved
whether or no there would appear
any con$iderable Diver$ity in the
Motion of the $hining Sparks in a
place where the remaining Aire was
$o much rarified, but could not perceive
<pb n=100>
but that they moved $ome of them up-
wards, as well as $ome of them down-
wards, and $ome of them $ide-ways, as
they are wont to do, when upon $uch col-
li$ions they fly out in the open Air.
<p>We likewi$e cau$'d a piece of Steel to
be made of the form and bigne$s of the
Flint, in who$e place we put it, and then
the Pi$tol being cock'd and conveyed in-
to the Receiver, the Trigger was pull'd
after the Air was drawn out: And though
the place were purpo$ely $omewhat dar-
ken'd, yet there appear'd not upon the
$triking of the two Steels again$t each o-
ther the lea$t $park of Fire: Nor did we
expect any (having before in vain attem-
pted to $trike Fire this way in the open
Air) though we thought fit to make the
Experiment to undeceive tho$e who fan-
cy in rarified Air, I know not what $trange
di$po$ition, to take Fire upon a much
$lighter occa$ion then this Experiment
afforded. We have indeed found, that
by the dextrous Colli$ion of two har-
den'd pieces of Steel, $tore of $parks
may be $truck out: But that was done with
$uch vehement percu$$ion of the edges of
the two Steels, as could not well be com-
pa$$'d in our Receiver.
<pb n=101>
<p>But the chief thing we de$ign'd to do
with our Pi$tol, was, To ob$erve whe-
ther Gun-powder would take Fire in our
empty'd and clo$ely $top'd Gla$s? Whe-
ther the expan$ion of the Flame would be
con$iderably varied by the ab$ence of $o
much of the ambient Air as was drawn
out of the Receiver? and whether the
Flame would diffu$e it $elf upward, as it is
wont, notwith$tanding its not having a-
bout it the u$ual proportion of Air to
force it up? And though mo$t of our at-
tempts to fire the Gun-powder in the
Pan of the Pi$tol $ucceeded not, becau$e
we were fain to let it hang almo$t perpen-
dicular in the Receiver; whereby the
Powder was $haken down before the
$parks could reach it: yet once the Ex-
periment $ucceeded, and the kindled
Powder $eem'd to make a more expanded
Flame then it would have done in the
open Air, but mounted upwards accord-
ing to its wont, whether by rea$on of that
little portion of Air, which in $pight of
our pumping remained in the Receiver, or
for any other cau$e, we have not now the
lei$ure to con$ider. But we mu$t not for-
get, that upon the extinction of the Flame
the Receiver appear'd darken'd with
<pb n=102>
$moke, which $eem'd to move freely up
and down, and upon the letting in the Air
at the Stop-cock began to circulate much
fa$ter then before. We wonld have made
more ob$ervations concerning this Flame,
but that of two or three attempts we
afterwards made to repeat the kindling of
Powder, not any one $ucceeded; and
we have not the lea$ure to dwell long up-
on one kinde of Tryals.
<p>TO the$e Experiments concerning Fire
<MARG><I>Experi-
ment</I> 15.</MARG>
we added another, which, though it $uc-
ceded not, may perhaps without imper-
tinency be recorded: partly becau$e that
(as we have in another Treati$e amply de-
clar'd) it is u$efull to recite what Experi-
ments mi$carry as well as what $ucceed.
And partly al$o becau$e it is very po$$ible
that what we endeavored in vaine, may be
performed by Your Lord$hip, or $ome
other <I>Virtuo$o</I> that $hall have $lancker
Ve$$ells then we had, and more Sunny
dayes then the pre$ent Winter allows
us.
<p>We convey'd then into one of our $mall
Receivers a piece of matter combu$tible,
dry and black (experience declaring things
<pb n=103>
of that colour to be mo$t ea$ily kindled)
&amp; carefully clo$ing the Ve$$el we brought
it to a Window at which the Sun, not very
faire from the Meridian, $hone in very free-
ly: then drawing out the Aire with $peed
united the Sun-beames with a burning
Gla$s upon the combu$tible matter which
began immediatly to $end forth a Smoke
that quickly darkned the Receiver, but
notwith$tanding all our care and diligence
the externall Aire got in $o fa$t that after
diver$e tryals we were fayne to leave off
the Experiment in that Gla$$e and induc'd
to make tryall of it in our great Re-
ceiver.
<p>Haveing then after $ome difficulty
lodg'd the combu$tible matter in the ca-
vity of this Ve$$ell in $uch manner as that
it was almo$t contiguous to that $ide
thereof that was next the Sun, we did en-
deavor with a pretty large burning Gla$s
to kindle it, but found, as we fear'd,
That by rea$on of the thickne$s of the
Gla$s, (which was al$o of a le$s pure and
le$s Diaphanous matter then the o-
ther) the Sun-beams thrown in by the
burning Gla$s, were in their pa$$age
$o Di$located and Scattered (not now to
mention tho$e many that being reflected,
<pb n=104>
I could not pierce into the cavity of the
Receiver) that we could not po$$ibly u-
nite enough of them to kindle the matter,
nor $o much as to make it $en$ibly $moke.
Yet we hope that the $eeing whether Bo-
dies (other then Gun-powder) may be
kindled, and what would happen to them
when $et on fire, in a place in great mea-
$ure devoid of Air, may prove $o Lucife-
rous an Experiment, that when the Sea-
$on is more favorable we $hall, God per-
mitting, make further tryal of it, and ac-
quaint Your Lord$hip with the Event, if
it prove pro$perous. In the mean time
we $hall pa$s on to other Experiments,
a$$oon as we have adverti$'d Your Lord-
$hip that we have forborn to make $uch
Reflections upon the $everal Experiments
we have $et down concerning Fire, as the
matter would have ea$ily enough afford-
ed, and Your Lord$hip may perhaps have
expected. But I made the le$s $cruple to
forbear the annexing of Speculations to
the$e Recitals, becau$e <I>Carneades</I> &amp; <I>Eleu-
therius</I> have in $ome Dialogues concern-
ing Heat and Flame, which were la$t year
$een by $ome Friends, and may be, when
you plea$e, commanded by You, men-
<pb n=105>
tion'd divers of my Thoughts and Expe-
riments concerning Fire.
<p>WE de$igned to try whether or no
<MARG><I>Experi-
ment</I> 16</MARG>
divers Magnetical Experiments
would exhibit any unu$ual <I>Ph&aelig;nomena,</I>
being made in our Evacuated Receiver
in$tead of the open Air: But for want of
lei$ure and conveniency to pro$ecute $uch
Tryals, we were induced to re$erve the
re$t for an other time, and to content our
$elves with making that which follows.
We convey'd into the Receiver a little
Pede$tal of Wood, in the mid$t of which
was perpendicularly erected a $lender
Iron, upon who$e $harp point an excited
Needle of Steel purpo$ely made, and of
about five Inches long, was $o placed
that hanging in an <I>&AElig;quilibrium</I> it could
move freely towards either hand. Then
the Air being after the u$ual manner
pumped out, we apply'd a Load-$tone
moderately vigorous to the out-$ide of
of the Gla$s, and found that it Attracted
or Repell'd the ends of the Needle, accor-
ding to the Laws Magnetical, without
any remarkable difference from what the
$ame Load-$tone would have done had
<pb n=106>
none of the Air been drawn away from a-
bout the Needle, which when the Load-
$tone was removed, after $ome tremu-
lous Vibrations to and fro, re$ted in a po-
$ition wherein it look'd North and
South.
<p>PRoceed we now to the mention of
<MARG><I>Experi-
ment</I> 17.</MARG>
that Experiment, whereof the $ati$-
factory tryal was the principal Fruit I
promi$'d my $elf from our Engine. It
being then $ufficiently known, that, in
the Experiment <I>De Vacuo,</I> the Quick-
$ilver in the Tube is wont to remain ele-
vated, above the $urface of that whereon
it leans, about 27 digits: I con$idered,
that, if the true and onely rea$on why the
Quick-$ilver falls no lower, be, that at
that Altitude, the Mercurial Cylinder in
the Tube, is an <I>&AElig;quilibrium</I> with the
Cylinder of Air, $uppo$'d to reach from
the adjacent Mercury to the top of the
Atmo$phere: If this Experiment could
be try'd out of the Atmo$phere, the
Quick-$ilver in the Tube would fall
down to a levell with that in the Ve$$el,
$ince then there would be no pre$$ure up-
on the Subjacent, to re$i$t the weight of
<pb n=107>
the Incumbent Mercury. Whence I in-
ferr'd (as ea$ily I might) that, if the Ex-
periment could be try'd in our Engine, the
Quick-$ilver would $ub$ide below 27 Di-
gits, in proportion to the ex$uction of
Air, that $hould be made out of the Re-
ceiver. For, as when the Air is $hut in-
to the Receiver, it does (according to
what hath above been taught) continue
there as $trongly compre$$'d, as it did
whil'$t all the incumbent Cylinder of the
Atmo$phere lean'd immediatly upon it;
becau$e the Gla$s, wherein it is pent up,
hinders it to deliver it $elf, by an expan$i-
on of its parts, from the pre$$ure where-
with it was $hut up. So, if we could per-
fectly draw the Air out of the Receiver,
it would conduce as well to our purpo$e,
as if we were allow'd to try the Experi-
ment beyond the Atmo$phere.
<p>Wherefore (after having $urmounted
$ome little difficulties which occurr'd at
the beginning) the Experiment was made
after this manner. We took a $lender and
very curiou$ly blown Cylinder of Gla$s,
of near three Foot in length, and who$e
bore had in Diameter a quarter of an Inch,
wanting a hairs breadth: This Pipe being
Hermetically $eal'd at one end, was, at
<pb n=108>
the other, fill'd with Quick-$ilver, care
being taken in the filling, that as few
bubles as was po$$ible $hould be left in the
Mercury: Then the Tube being $topt
with the Finger and inverted, was open'd,
according to the manner of the Experi-
ment, into a $omewhat long and $lender
Cylindrical Box (in$tead of which we now
are wont to u$e a Gla$s of the $ame form)
half fill'd with Quick-$ilver: And $o, the
liquid metal being $uffered to $ub$ide, and
a piece of Paper being pa$ted on levell
with its upper $urface, the Box and Tube
and all were by $trings carefully let down
into the Receiver, and then, by means of
the hole formerly mention'd to be left in
the Cover, the $aid Cover was $lip't along
as much of the Tube as reach'd above the
top of the Receiver; And the Interval,
left betwixt the $ides of the Hole and
tho$e of the Tube, was very exqui$itely
fill'd up with melted (but not over hot)
Diachylon; and the round chink, betwixt
the Cover and the Receiver, was likewi$e
very carefully clo$'d up: Upon which clo-
$ure there appear'd not any change in the
height of the Mercurial Cylinder; no
more, then if the interpo$'d Gla$s Recei-
ver did not hinder the immediate pre$$ure
<pb n=109>
of the ambient Atmo$phere upon the
inclo$ed Air; which hereby appears to
bear up on the Mercury, rather by virtue
of its $pring, then of its weight: $ince its
weight cannot be $uppo$'d to amount to
above two or three Ounces, which is in-
con$iderable in compari$on of $uch a Cy-
linder of Mercury as it would keep from
$ub$iding.
<p>All things being thus in a readine$s, the
Sucker was drawn down; and, immedi-
ately upon the egre$s of a Cylinder of
Air out of the Receiver; the Quick-$ilver
in the Tube did, according to expectati-
on, $ub$ide: and notice being carefully
taken (by a mark fa$ten'd to the out$ide)
of the place where it $topt, we cau$'d him
that manag'd the Pump to pump again,
and mark'd how low the Quick-$ilver fell
at the $econd ex$uction; but continuing
this work, we were quickly hindred from
accurately marking the Stages made by
the Mercury in its de$cent, becau$e it $oon
$unk below the top of the Receiver; $o
that we could thenceforward mark it no
other ways then by the eye. And thus,
continuing the labor of pumping for a-
bout a quarter of an hour, we found our
$elves unable to bring the Quick-$ilver in
<pb n=110>
the Tube totally to $ub$ide; becau$e,
when the Receiver was con$iderably em-
pty'd of its Air, and con$equently that
little that remain'd grown unable to re$i$t
the Irruption of the external, that Air
would (in $pight of whatever we could
do) pre$s in at $ome little Avenue or
other; and though much could not there-
at get in, yet a little was $ufficient to coun-
terballance the pre$$ure of $o $mall a Cy-
linder of Quick-$ilver, as then remain'd
in the Tube.
<p>Now (to $atisfie our $elves further, that
the failing of the Quick-$ilver in the
Tube to a determinate height, proceeds
from the <I>&AElig;quilibrium,</I> wherein it is at
that height with the external Air, the one
gravitating, the other pre$$ing with equal
force upon the $ubjacent Mercury) we Re-
turned the Key and let in $ome new Air;
upon which the Mercury immediatly be-
gan to a$cend (or rather to be impell'd up-
wards) in the Tube, and continu'd a$cend-
ing, till having Return'd the Key it im-
mediatly re$ted at the height which it had
then attain'd: And $o, by Turning and
Returning the Key, we did $everal times
at plea$ure impel it upwards, and check its
a$cent. And la$tly, having given a free
<pb n=111>
egre$s at the Stop-cock to as much of the
external Air as would come in, the Quick-
$ilver was impell'd up almo$t to its fir$t
height: I $ay almo$t, becau$e it $topt
near a quarter of an Inch beneath the Pa-
per mark formerly mention'd; which we
a$crib'd to this, That there was (as is u-
$ual in this Experiment) $ome little Parti-
cles of Air engag'd among tho$e of the
Quick-$ilver; which Particles, upon the
de$cent of the Quick-$ilver, did manife$t-
ly ri$e up in Bubbles towards the top of
the Tube, and by their pre$$ure, as well
as by le$$ening the Cylinder by as much
room as they formerly took up in it, hin-
der'd the Quick-$ilver from regaining its
fir$t height.
<p>This Experiment was a few days after
repeated in the pre$ence of tho$e excellent
and de$ervedly Famous Mathematick
Profe$$ors, Dr. <I>Wallis,</I> Dr. <I>Ward,</I> and Mr.
<I>Wren,</I> who were plea$ed to Honor it with
their Pre$ence: And whom I name, both
as ju$tly counting it an Honor to be
known to them, and as being glad of $uch
Judicious and illu$trious Witne$$es of our
Experiment; and 'twas by their gue$s that
the top of the Quick-$ilver in the Tube
was defin'd to be brought within an Inch
<pb n=112>
of the $urface of that in the Ve$$el.
<p>And here, for the Illu$tration of the
foregoing Experiment, it will not be a-
mi$s to mention $ome other particulars
relating to it.
<p>Fir$t then, When we endeavor'd to
make the Experiment with the Tube
clo$'d at one end with <I>Diachylon</I> in$tead
of an Hermetical Seal; we perceiv'd, that
upon the drawing of $ome of the Air out
of the Receiver, the Mercury did indeed
begin to fall, but continu'd afterwards to
$ub$ide, though we did not continue pum-
ping. Whence it appear'd, that though
the <I>Diachylon</I> that $topt the end of the
Tube were $o thick and $trong, that the
external Air could not pre$s it in (as expe-
rience taught us that it would have done,
if there had been but little of it) yet the
$ubt'ler parts of it were able (though
$lowly) to in$inuate them$elves through
the very body of the Plai$ter, which it
$eems was of $o clo$e a Texture, as that
which we mention'd our $elves to have
$ucce$sfully made u$e of in the Experi-
ment <I>De Vacuo</I> $ome years ago. So that
now we begin to $u$pect, that perhaps one
Rea$on, why we cannot perfectly pump
out the Air, may be, that when the Ve$$el
<pb n=113>
is almo$t empty, $ome of the $ubtler
parts of the external Air may, by the
pre$$ure of the Atmo$phere, be $train'd
through the very body of the <I>Diachylon</I>
into the Receiver. But this is onely con-
jecture:
<p>Another Circum$tance of our Expe-
riment was this, That, if (when the
Quick-$ilver in the Tube was fallen low)
too much ingre$s were, at the hole of the
Stop-cock, $uddenly permitted to the ex-
ternal Air; it would ru$h in with that vio-
lence, and bear $o forcibly upon the $ur-
face of the $ubjacent Quick-$ilver, that
it would impel it up into the Tube rudely
enough to endanger the breaking of the
Gla$s.
<p>We formerly mention'd, that the
Quick-$ilver did not in its de$cent fall as
much at a time after the two or three fir$t
ex$uctions of the Air, as at the beginning:
For, having mark'd its $everal Stages up-
on the Tube, we found, that at the fir$t
$uck it de$cended an Inch and 3/8, and at the
$econd an Inch and 1/8; and when the Ve$-
$el was almo$t empty'd, it would $carce at
one ex$uction be drawn down above the
breadth of a Barly-corn. And indeed we
found it very difficult to mea$ure in what
<pb n=114>
proportion the$e decrements of the Mer-
curial Cylinder did proceed: partly be-
cau$e (as we have already intimated) the
Quick $ilver was $oon drawn below the
top of the Receiver: and partly becau$e,
upon its de$cent at each ex$uction, it
would immediatly rea$cend a little up-
wards; either by rea$on of the leaking of
the Ve$$el at $ome imperceptible hole or
other, or by rea$on of the motion of
Re$titution in the Air, which, b<*>ng $ome-
what compre$t by the fall as well as weight
of the Quick $ilver, would repell it a lit-
tle upwards, and make it vibrate a little up
and down, before they could reduce each
other to $uch an <I>&AElig;quilibrium</I> as both
might re$t in. But though we could not
hitherto make ob$ervations accurate e-
nough concerning the mea$ures of the
Quick-$ilver's de$cent, to reduce them in-
to any <I>Hypothe$is,</I> yet would we not di$-
courage any from attempting it: $ince, if it
could be reduc'd to a certainty, tis proba-
ble that the di$covery would not be un-
u$eful.
<p>And, to illu$trate this matter a little
more, we will adde, That we made a $hift
to try the Experiment in one of our above
mention'd $mall Receivers, not containing
<pb n=115>
a Quart; but that (agreeably to what we
formerly ob$erved) we found it as difficult
to bring this to be quite empty as to eva-
cuate the greater; the lea$t external Air
that could get in (and we could not po$$i-
bly keep it all perfectly out) $ufficing in $o
$mall a Ve$$el to di$play a con$iderable
pre$$ure upon the $urface of the Mercury,
and thereby hinder that in the Tube from
falling to a level with it. But this is remark-
able, that having two or three times try'd
the Experiment in that $mall Ve$$el, upon
the very fir$t Cylinder of Air that was
drawn out of the Receiver, the Mercury
fell in the Tube 18 Inches and a half, and
at another 19 Inches and a half.
<p>But, on this occa$ion, I hold it not un-
fit to give Your Lord$hip notice that I
hop'd, from the de$cent of the Quick-
$ilver in the Tube upon the fir$t $uck, to
derive this advantage: that I $hould thence
be enabled to give a near gue$s at the pro-
portion of force betwixt the pre$$ure of
the Air (according to its various $tates, as
to Den$ity and Rarefaction) and the gra-
vity of Quick-$ilver, then hitherto has
been done. For in our Experiment there
are diver$e things given, that may be
made u$e of towards $uch a di$covery.
<pb n=116>
For fir$t we may know the capacity of the
Receiver wherein the Experiment is
made, $ince, by filling it with water, we
may ea$ily compute how many Quarts, or
Mea$ures of any other denomination, it
contains of Air; which Air, when $hut
up in the Ve$$el, may be $uppo$'d to have
a pre$$ure equal to that of the Atmo-
$phere; $ince it is able to keep the Quick-
$ilver in the Tube from falling any lower
then it did in the free and open Air. Next
here is given us the capacity of the bra$s
Cylinder empty'd by the drawing down
of the Sucker (its bore and height being
mention'd in the de$cription of our Pump)
whereby we may come to know how
much of the Air contain'd in the Recei-
ver is drawn out at the fir$t $uck. And
we may al$o ea$ily define, either in weight
or cubick mea$ures the Cylinder of
Quick-$ilver that an$wers to the Cy-
linder of Air lately mention'd (that
Mercuriall Cylinder being in our En-
gine computable by deducting from
the entire altitude or that Cylinder of
Quick-$ilver, the altitude at which it re$ts
upon the fir$t ex$uction.) But though, if
this Experiment were very watchfully
try'd in Ve$$els of $everal $izes, and the
<pb n=117>
various de$cents of the Quick-$ilver com-
par'd among them$elves, 'tis not impro-
bable that $ome $uch thing as we hop'd for
may thereby be di$cover'd. Yet becau$e
not onely the $olid contents of as much
of the Gla$s-tube as remains within the
concave $urface of the Receiver, and
(which is more difficult) the varying con-
tents of the Ve$$el containing the Mer-
cury, and of as much of the Mercury it
$elf as is not in the Tube, mu$t be dedu-
cted out of the capacity of the Receiver;
but there mu$t al$o an allowance be made
for this, that the Cylinder that is empty'd
by the drawing down of the Sucker, and
comes to be fill'd upon the letting of the
Air out of the Receiver into it, is not $o
repleni$h'd with Air as the Receiver it $elf
at fir$t was: becau$e there pa$$es no more
Air out of the Receiver into the Cylin-
der, then is requi$ite to reduce the Air in
the cavity of the Cylinder, and in that of
the Receiver to the $ame mea$ure of dila-
tation: Becau$e of the$e (I $ay) and $ome
other difficulties that require more skill in
Mathematicks then I pretend to, and much
more lea$ure then my pre$ent occa$ions
would allow me, I was willing to refer the
nicer con$ideration of this matter to $ome
<pb n=118>
of our Learned and Acurate Mathema-
ticians, thinking it enough for me to have
given the Hint already $ugge$ted.
<p>For further confirmation of what hath
been delivered, we likewi$e tryed the Ex-
periment in a Tube of le$s then two foot
long: and, when there was $o much Air
drawn out of the Ve$$el, that the remain-
ing Air was not able to counterballance
the Mercurial Cylinder, the Quick-$ilver
in the Tube $ub$ided $o vi$ibly, that (the
Experiment being try'd in the little Ve$-
$el lately mention'd) at the fir$t $uck it
fell above a $pan, and was afterwards
drawn lower and lower for a little while;
and the external Air being let in upon it,
impell'd it up again almo$t to the top of
the Tube: So little matters it how heavy
or light the Cylinder of Quick $ilver to
$ub$ide is, provided its gravity over-
power the pre$$ure of as much external
Air as bears upon the $urface of that Mer-
cury into which it is to fall.
<p>La$tly we al$o ob$erv'd, That if (when
the Mercury in the Tube had been drawn
down, and by an Ingre$s permitted to the
external Air, impell'd up again to its for-
mer height) there were $ome more Air
thru$t up by the help of the Pump into
<pb n=119>
the Receiver, the Quick-$ilver in the Tube
would a$cend much above the wonted
height of 27 digits, and immediatly up-
on the letting out of that Air would fall a-
gain to the height it re$ted at before.
<p>Your Lord$hip will here perhaps expect,
that as tho$e who have treated of the <I>Tor-
ricellian</I> Experiment, have for the mo$t
part maintaind the Affirmative, or the Ne-
gative of that famous Que$tion, Whether
or no that Noble Experiment infer a <I>Va-
cuum?</I> $o I $hould on this occa$ion inter-
po$e my Opinion touching that Contro-
ver$ie, or at lea$t declare whether or no, in
our Engine, the ex$uction of the Air do
prove the place de$erted by the Air $uck'd
out, to be truly empty, that is, devoid of
all Corporeal Sub$tance. But be$ides that,
I have neither the lei$ure, nor the ability,
to enter into a $olemn Debate of $o nice a
Que$tion; Your Lord$hip may, if you
think it worth the trouble, in the Dia-
logues not long $ince referr'd to, finde the
Difficulties on both $ides repre$ented;
which then made me yield but a very wa-
vering a$$ent to either of the parties con-
tending about the Que$tion: Nor dare I
yet take upon me to determine $o difficult
a Controver$ie.
<pb n=120>
<p>For on the one $ide it appears, that not-
with$tanding the ex$uction of the Air, our
Receiver may not be de$titute of all Bo-
dies, $ince any thing placed in it, may be
$een there; which would not be, if it
were not pervious to tho$e Beams of
Light which rebounding from the $een
Object to our eyes, affect us with the $en$e
of it: And that either the$e Beams are
Corporeal Emanations from $ome lucid
body, or el$e at lea$t the light they convey
doth re$ult from the brisk Motion of $ome
$ubtle Matter, I could, if I mi$take not,
$ufficiently manife$t out of the Dialogues
above-mention'd, if I thought your Lord-
$hip could $eriou$ly imagine that Light
could be convey'd without, at lea$t, having
(if I may $o $peak) a Body for its Ve-
hicle.
<p>By the $ixteenth Experiment, it al$o
appears that the clo$ene$s of our Receiver
hinders it not from admitting the Efflu-
via of the Load-$tone; which makes it
very probable that it al$o freely admits
the Magnetical $teams of the Earth; con-
cerning which, we have in another Trea-
ti$e endeavour'd to manife$t that numbers
of them do always permeate our Air.
<p>But on the other $ide it may be $aid,
<pb n=121>
That as for the $ubtle Matter which makes
the Objects enclo$ed in our evacuated Re-
ceiver, vi$ible, and the Magnetical Efflu-
via of the Earth that may be pre$um'd to
pa$s thorow it, though we $hould grant
our Ve$$el not to be quite devoyd of
them, yet we cannot $o rea$onably affirm
it to be repleni$h'd with them, as we may
$uppo$e, that if they were gather'd toge-
ther into one place without Intervals be-
tween them, they would fill but a $mall
part of the whole Receiver. As in the
thirteenth Experiment, a piece of Match
was incon$iderable for its bulk, while$t its
parts lay clo$e together, that afterwards
(when the Fire had $catter'd them into
$moke) $eem'd to repleni$h all the Ve$$el.
For (as el$ewhere our Experiments have
demon$trated) both Light and the Efflu-
via of the Load-$tone, may be readily ad-
mitted into a Gla$s, Hermetically $eal'd,
though before their Admi$$ion, as full of
Air as hollow Bodies here below are wont
to be, $o that upon the ex$uction of the
Air, the large $pace de$erted by it, may
remain empty, notwith$tanding the pre-
tence of tho$e $ubtle Corpu$cles, by
which Lucid and Magnetical Bodies pro-
duce their effects.
<pb n=122>
<p>And as for the Allegations above
mention'd, they $eem to prove but that
the Receiver devoy'd of Air, <I>May</I> be re-
pleni$h'd with $ome $uch Etherial Matter,
as $ome Modern Naturali$ts write of; but
not that it really <I>is</I> $o. And indeed to me
it yet $eems, that as to tho$e $paces which
the <I>Vacui$ts</I> would have to be empty, be-
cau$e they are manife$tly devoid of Air;
and all gro$$er Bodies, the <I>Pleni$ts</I> (if I
may $o call them) do not prove that $uch
$paces are repleni$h'd with $uch a $ubtle
Matter as they $peak of, by any $en$ible
effects, or operations of it (of which di-
vers new Tryals purpo$ely made, have not
yet $hown me any) but onely conclude
that there mu$t be $uch a Body, becau$e
there cannot be a Void. And the rea$on
why there cannot be a Void, being by
them taken, not from any Experiments,
or <I>Ph&aelig;nomena</I> of Nature, that clearly and
particularly prove their <I>Hypothe$is,</I> but
from their notion of a Body, who$e Na-
ture, according to them, con$i$ting one-
ly in exten$ion (which indeed $eems the
property mo$t e$$ential to, becau$e in$epa-
rable from a Body) to $ay a $pace devoid
of Body, is to $peak in the School-mens
Phra$e, a Contradiction <I>in Adjecto:</I> This
<pb n=123>
rea$on, I $ay, being thus de$um'd, $eems
to make the Controver$ie about a <I>Vacu-
um,</I> rather a Metaphy$ical, then a Phy$io-
logical Que$tion; which therefore we $hall
here no longer debate, finding it very dif-
ficult either to $atisfie Naturali$ts with
this Carte$ian Notion of a Body, or to
manife$t wherein it is erroneous, and $ub-
$titute a better in its $tead.
<p>But though we are unwilling to exa-
mine any further the Inferences wont to
be made from the <I>Torricellian</I> Experi-
ment, yet we think it not impertinent to
pre$ent Your Lord$hip with a couple of
Adverti$ements concerning it.
<p>Fir$t, then if in trying the Experiment
here or el$ewhere, you make u$e of the
Engli$h mea$ures that Mathematicians
and Trade$men are here wont to imploy,
You will, unle$s you be forewarn'd of it,
be apt to $u$pect that tho$e that have writ-
ten of the Experiment have been mi$ta-
ken. For whereas men are wont gene-
rally to talk of the Quick-$ilver's remain-
ing $u$pended at the heighth of between
$ix or $even and twenty Inches; we com-
monly ob$erv'd, when divers years $ince
we fir$t were $ollicitous about this Expe-
riment, that the Quick-$ilver in the Tube
<pb n=124>
re$ted at about 29 Inches &amp; an half above
the $urface of the Re$tagnant Quick-$ilver
in the Ve$$el, which did at fir$t both amaze
and perplex us, becau$e though we held it
not improbable that the difference of the
gro$$er Engli$h Air, and that of <I>Italy</I> and
<I>France,</I> might keep the Quick-$ilver from
falling quite as low in this colder, as in
tho$e warmer Climates; yet we could
not believe that that difference in the Air
$hould alone be able to make $o great a one
in the heights of the Mercurial Cylinders;
and accordingly upon enquiry we found,
that though the various den$ity of the
Air be not to be over-look'd in this Ex-
periment, yet the main Rea$on why we
found the Cylinder of Mercury to con$i$t
of $o many Inches, was this, That our
Engli$h Inches are $omewhat inferior in
length to the digits made u$e of in Fo-
rein Parts, by the Writers of the Expe-
riment.
<p>The next thing I de$ire Your Lord$hip to
take notice of, is, That the heigth of the
Mercurial Cylinder is not wont to be fo&utilde;d
altogether $o great as really it might
prove, by rea$on of the negligence or in-
cogitancy of mo$t that make the Experi-
ment. For often times upon the opening
<pb n=125>
of the inverted Tube into the Ve$$ell'd
Mercury, you may ob$erve a bubble of
Air to a$cend from the bottom of the
Tube through the $ub$iding Quick-$ilver
to the top; and almo$t always you may,
if you look narrowly, take notice of a
multitude of $mall bubbles all along the
in$ide of the Tube betwixt the Quick-
$ilver &amp; the gla$s: (not now to mention the
Particles of Air that lye conceal'd in the
very Body of the Mercury) Many of
which, upon the Quick-$ilvers for$aking
the upper part of the Tube, do break in-
to that de$erted $pace where they finde
little or no re$i$tance to their expanding
of them$elves. Whether this be the rea-
$on that upon the Application of warm
Bodies to the emptyed part of the Tube,
the $ubjacent Mercury would be depre$$'d
$omewhat lower, we $hall not determine;
though it $eem very probable, e$pecially
$ince we found that upon the application
of Linnen cloaths dipped in Water, to
the $ame part of the Tube, the Quick-
$ilver would $omewhat a$cend, as if the
cold had conden$'d the Impri$on'd Air,
that pre$$'d upon it, into a le$$er room.
But that the de$erted $pace is not wont to
be totally devoid of Air, we were induc'd
<pb n=126>
to think by $everal Circum$tances. For
when an eminent Mathematician, and ex-
cellent Experimenter, had taken great
pains and $pent much time in accuratly fil-
ling up a Tube of Mercury, we found
that yet there remain'd $tore of incon$pi-
cuous bubbles, by inverting the Tube,
letting the Quick-$ilver fall to its wonted
heighth; and by approaching (by de-
grees) a red hot Iron to the out-$ide of the
Tube, over again$t the upper part of the
Mercurial Cylinder, for hereby the little
unheeded bubbles, being mightily expan-
ded, a$cended in $uch numbers, and $o fa$t
to the de$erted $pace, that the upper part
of the Quick-$ilver $eem'd, to our wonder,
to boyl. We further ob$erv'd, That in
the tryals of the <I>Torricellian</I> Experiment
we have $een made by others, and (one
excepted) all our own, we never found that
upon the inclining of the Tube the Quick-
$ilver would fully reach to the very top of
the $eal'd end: which argued, that there
was $ome Air retreated thither that kept
the Mercury out of the unrepleni$h'd
$pace.
<p>If Your Lord$hip $hould now demand
what are the be$t expedients to hinder the
intru$ion of the Air in this Experiment;
<pb n=127>
we mu$t an$wer, That of tho$e which are
ea$ily intelligible without ocular demon-
$tration, we can at pre$ent $ugge$t upon
our own tryals no better then the$e. Fir$t,
at the open end of the Tube the Gla$s
mu$t not onely be made as even at the ed-
ges as you can, but it is very conveni-
ent (e$pecially if the Tube be large) that
the bottom be every way bent inwards,
that $o the Orifice, not much exceeding a
quarter of an Inch in Diameter, may be
the more ea$ily and exactly $topp'd by the
Experimenter's finger; between which
and the Quick-$ilver, that there may be
no Air intercepted (as very often it hap-
pens that there is) it is requi$ite that the
Tube be fill'd as full as po$$ibly it can be,
that the finger which is to $top it, pre$$ing
upon the accumulated and protuberant
Mercury, may rather throw down $ome,
then not finde enough exactly to keep out
the Air. It is al$o an u$eful and compen-
dious way not to fill the Tube at fir$t
quite ful of Mercury, but to leave near the
top about a qnarter of an Inch empty; for
if you then $top the open end with your
finger, and invert the Tube that quarter
of an Inch of Air will a$cend in a great
bubble to the top, and in its pa$$age thi-
<pb n=128>
ther, will gather up all the little bubbles,
and unite them with it$elf into one great
one, $o that if by reinverting the Tube
you let that bubble return to the open
end of it, you will have a much clo$er Mer-
curial Cylinder then before, and need but
to adde a very little Quick-$ilver more to
fill up the Tube exactly. And la$tly, as for
tho$e le$$er and incon$picuous parcels of
Air which cannot this way be gleaned up,
You may endeavor before you invert the
Tube, to free the Quick-$ilver from them
by $haking the Tube, and gently knock-
ing on the out-$ide of it, after every little
parcel of Quick-$ilver which you pour in;
and afterwards, by forcing the $mall la-
titant bubbles of Air to di$clo$e them-
$elves and break, by imploying a hot Iron
in $uch manner as we lately mention'd. I
remember that by carefully filling the
Tube, though yet it were not quite free
from Air, we have made the Mercurial
Cylinder reach to 30 Inches and above an
eighth, and this in a very $hort Tube:
which we therefore mention, becau$e we
have found, by experience, that in $hort
Tubes a little Air is more prejudicial to
the Experiment then in long ones, where
the Air having more room to expand it
<pb n=129>
$elf, does le$s potently pre$s upon the $ub-
jacent Mercury.
<p>And $ince we are fallen upon the con$i-
deration of the Altitude of the Mercurial
Cylinder, I mu$t not conceal from Your
Lord$hip an Experiment relating thereun-
to, which perhaps will $et both You and
many of your Friends the <I>Virtuo$i</I> a think-
ing; and, by di$clo$ing $ome things a-
bout the Air or Atmo$phere that have
$carce hitherto been taken notice of, may
afford you $ome hints conducive to a fur-
ther di$covery of the $ubject of this E-
pi$tle.
<p>WE took a Gla$s Tube, which,
<MARG><I>Experi-
ment</I> 18.</MARG>
though it were not much above
three Foot long, we made choice of be-
cau$e it was of a more then ordinarily
even thickne$s. This we fill'd with Mer-
cury, though not with as much care as we
could, yet with $omewhat more then is
wont to be u$ed in making the <I>Torricellian</I>
Experiment. Then, having according to
the manner inverted the Tube, and open'd
the mouth of it beneath the $urface of
$ome other Quick-$ilver, that in the Tube
fell down to the wonted heigth, leaving,
<pb n=130>
as is u$ual, $ome little Particles of Air in
the $pace it de$erted, as we ghe$t by ob-
$erving, that upon the Application of hot
Bodies to the upper part of the Tube, the
Quick-$ilver would be a little depre$$'d.
La$tly, having put both the Tube and the
Ve$$el it lean'd on into a convenient
Wooden Frame, to keep them from mi$-
chances: we plac'd that Frame in a Win-
dow within my Bed-chamber, that I might
both keep the Mercury from being $tirr'd,
and have opportunity to watch from time
to time the <I>Ph&aelig;nomena</I> it was to exhibit.
For the better di$covery of which, when
the Quick-$ilver both in the Tube and
$ubjacent Ve$$el was perfectly at re$t, we
took notice, by a mark made on the out-
$ide of the Gla$s, how high the included
Liquor then reach'd.
<p>During $everal Weeks that the Tube
was kept in that Window (which was very
rarely open'd) I had the opportunity to
ob$erve, that the Quick-$ilver did $ome-
times faintly imitate the Liquor of a
Weather-gla$s, $ub$iding a little in warm,
and ri$ing a little in cold Weather, which
we a$cribed to the greater or le$$er pre$$ure
of that little Air that remain'd at the top
of the Tube, expanded or conden$'d by
<pb n=131>
the heat or cold that affected the ambient
Air. But that which I was chiefly careful
to ob$erve, was this, That oftentimes the
Quick-$ilver did ri$e and fall in the Tube,
and that very notably, without conforming
it $elf to what is u$ual in Weather-gla$$es,
who$e Air is at the top, nay quite contrary
thereunto: for $ometimes I ob$erv'd it in
very cold weather ($uch as this Winter has
already afforded us good $tore of) to fall
down much lower then at other times,
when by rea$on of the ab$ence of both
Fro$t, Snow, and $harp Winds, the Air was
comparatively much warmer. And I fur-
ther ob$erv'd, That $ometimes the Quick-
$ilver would for $ome days together re$t
almo$t at the $ame height; and at other
times again it would in the compa$s of the
$ame day con$iderably vary its altitude,
though there appear'd no change either in
the Air abroad, or in the temper of the Air
within the Room (wherein was con$tantly
kept a good Fire) nor in any thing el$e, to
which either I, or $ome eminently Learned
Men whom I then acquainted with the
Experiment, could rea$onably impute
$uch a change: E$pecially con$idering that
the $pace wherein the Mercury wandred up
and down, within about five Weeks, a-
mounted to full two Inches, of which we
<pb n=132>
found by our $everal marks whereby we
had taken notice of its $everal removes, that
it had de$c&etilde;ded about (9/16) of an Inch from the
place where it fir$t $etled, &amp; the other Inch
and (7/16) it had a$cended. And it $eems pro-
bable that the height of the Mercurial Cy-
linder would have varied yet more, if the
Experiment had been made in the open
Air and in a long Tube, where the Parti-
cles of the Impri$on'd Air, by having
more room to di$play them$elves in,
might not have had $o $trong a Spring to
work upon the Quick-$ilver with. But for
want both of time and of a competent
quantity of Mercury (which was not to be
procur'd where we then happen'd to be)
we were unable to make any further try-
als: which therefore chiefly troubled us,
becau$e we would gladly have try'd an in-
genious Experiment which was $ugge$ted
unto us by that excellent Mathematician
Mr. <I>Wren,</I> who being invited to name any
thing he would have us try touching the
pre$$ure of the Air, de$ired us to ob$erve
whether or no the Quick-$ilver in a long
Tube would not a little vary its height ac-
cording to the Tides, e$pecially about the
New and Full Moon, about which times
Mariners ob$erve tho$e great Flowings
and Ebbs of the Sea, that they call the
<pb n=133>
Spring-Tides. For he $agaciou$ly and
plau$ibly conjectur'd that $uch ob$ervati-
ons accurately made, would di$cover the
truth or erroneou$ne$s of the <I>Carte$ian
Hypothe$is</I> concerning the Ebbing and
Flowing of the Sea: which <I>Des Cartes</I>
a$cribes to the greater pre$$ure made upon
the Air by the Moon, and the Intercur-
rent Ethereal Sub$tance at certain times
(of the Day, and of the Lunary Moneth)
then at others. But in regard we found
the Quick-$ilver in the Tube to move up
and down $o uncertainly, by rea$on, as it
$eems, of accidental mutation in the Air;
I $omewhat doubt whether we $hall finde
the Altitude of the Quick-$ilver to vary
as regularly as the Experiment is ingeni-
ou$ly propo$'d. The $ucce$s we $hall (God
permitting us to make tryal of it) acquaint
Your Lord$hip with; and in the mean
time take notice, that when we had occa-
$ion to take the Tube out of the Frame
(after it had $taid there part of <I>November</I>
and part of <I>December</I>) a good Fire being
then in the room, becau$e it was a Snowy
day, we found the Quick-$ilver in the
Tube to be above the upper $urface of
the $ubjacent Mercury 29 Inches three
quarters.
<pb n=134>
<p>If Your Lord$hip $hould now ask me
what are the true cau$es of this varying al-
titude of the Mercurial Cylinder; I $hould
not undertake to an$wer $o difficult a que-
$tion, and $hould venter to $ay no more,
then that among divers po$$ible cau$es to
which it may be a$cribed, it would not be,
perhaps, ab$urd to reckon the$e that fol-
low.
<p>Fir$t then we may con$ider, that the Air
in the upper part of the Tube is much
more rarified, and therefore more weak
then the external Air, as may appear by
this among other things, That upon the in-
clining of the Tube the Quick-$ilver will
readily a$cend almo$t to the very top of
it, and $o take up eight or nine tenth parts,
and perhaps more of that $pace which it
de$erted before: which would not happen
if that whole $pace had been full of unra-
rified Air, $ince that (as tryal may ea$ily
$atisfie you) would not have $uffer'd it
$elf to be thru$t into $o narrow a room by
$o weak a pre$$ure. So that although in
our Tube when the included Air was
heated, the Quick-$ilver was $omewhat
depre$$'d: Yet there is this difference be-
twixt $uch a Tube and common Weather-
Gla$$es, that in the$e the included and the
<pb n=135>
ambient Air are in an <I>&AElig;quilibrium</I> as to
pre$$ure, and the weight of the Water
that keeps them $eparate is $carce con$i-
derable. Whereas in $uch a Tube as we
are $peaking of, the Air within is very
much more dilated then that without; and
'tis not $o much the $pring or re$i$tance
of the included Air, as the weight of the
Mercurial Cylinder it $elf that hinders the
Quick-$ilver from a$cending higher; for
if we $hould $uppo$e that de$erted part of
the Tube perfectly devoid of Air, yet
would the Quick-$ilver ri$e but a little
higher in it, and be far from filling it, in
regard the outward Air would not be
able to impel up $uch a weight much
higher: whereas it may, by our former
Experiments appear, that if all the Air in
the upper part of a Weather-Gla$s were
away, the Water would be impell'd up to
the very top of it, though the Pipe were
above thirty Foot long.
<p>We may next con$ider, that this ra-
rified Air at the upper part of our Tube
being exactly $hut up betwixt the Gla$s
and the Quick-$ilver, it was $carce $ubject
to any di$cernable alterations, $ave tho$e
it receiv'd from heat and cold.
<pb n=136>
<p>And we may further con$ider that yet
the external Air or Atmo$phere is $ubject
to many alterations, be$ides them that
proceed from either of tho$e Quali-
ties.
<p>For the Experiment that occa$ion'd
this Di$cour$e, $eems to make it proba-
ble enough that there may be $trange
Ebbings and Flowings, as it were, in the
Atmo$phere; or at lea$t, that it may ad-
mit great and $udden Mutations, either as
to its Altitude or its Den$ity, from cau$es,
as well unknown to us, as the effects are
unheeded by us. And that You may not
think that there is nothing in Nature but
our Experiment that agrees with this our
conjecture, we might put Your Lord$hip
in minde of the Pains and Aches that are
often complain'd of by tho$e that have
had great Wounds or Brui$es, and that
doe pre$age great Mutations in the Air
oftentimes, whil$t to $trong and healthy
Per$ons no $ign of any $uch thing appears.
And that is al$o very memorable to this
purpo$e, which I remember I have $ome-
where read in a Book of the Ingenious
<I>Kircherus,</I> who giving a pertinent admoni-
tion concerning the various refractions
that may happen in the Air, relates, That
<pb n=137>
during his $tay in <I>Malta,</I> he often $aw
Mount <I>&AElig;tna,</I> though the next day, not-
with$tanding its being extreamly clear, he
could not $ee it; adding, that <I>Vintemillius,</I>
a very Learned Per$on, did oftentimes,
from a Hill he names, behold the whole
I$land he calls <I>Luprica</I> protuberant above
the Sea, though at other times, notwith-
$tanding a clear Sky, he could not $ee it.
And though perhaps this may be in part a-
$cribed to the various light &amp; po$ition of
the $un, or to the various di$po$ition of the
Spectators eye, or peradventure to $ome
other cau$e; yet the mo$t probable cau$e
$eems to be the differing Den$ity of the
Air, occa$ion'd by Exhalations capable to
increa$e the refraction, and con$equently
bring Beams to the Eye, which otherwi$e
would not fall on it. We have likewi$e
in another Treati$e mention'd our having
often ob$erv'd with Tele$copes a plenty
of Steams in the Air, which without $uch
a help would not be taken notice of, and
which as they were not at all times to be
$een even through a Tele$cope, $o they
did $ometimes, e$pecially after a $hower of
Rain, ha$tily di$appear: and when we
have vi$ited tho$e places that abound with
Mines, we have $everal times been told
<pb n=138>
by the Diggers, that even when the Sky
$eem'd clear, there would not $eldom $ud-
denly ari$e, and $ometimes long continue,
a certain Steam (which they u$ually call a
damp) $o gro$s and thick, that it would
oftentimes put out their very Candles, if
they did not $ea$onably prevent it. And
I think it will ea$ily be granted, that the
a$cen$ion of $uch Steams into this or that
part of the Air, and their mixing with it,
are very like to thicken it; as on the o-
ther $ide either heat or the $udden conden-
$ation of the Air in another part of the At-
mo$phere (to mention now no other cau-
$es) are capable of rarifying it.
<p>Nor will it very much import the main
$cope of our Di$cour$e, whether it be
$uppo$'d that the copious Steams the
earth $ends into the air, thicken that part
of the Atmo$phere that receives them,
and make it more heavy: Or that $ome-
times the Fumes may a$cend with $uch ce-
lerity, that though the Air be thicken'd
yet they rather dimini$h then en<*>ea$e its
gravitation, in regard that the quickne$s
of their a$cent, not onely keeps them
from gravitating them$elves, but may
hinder the pre$$ing downwards of many
A&euml;rial Corpu$cles that they meet with in
<pb n=139>
their way upwards. This, I $ay, is of
no great importance to our pre$ent Di$-
cour$e, $ince either way the Terre$trial
Steam may here and there con$iderably
alter the gravity or pre$$ure of the At-
mo$phere.
<p>Your Lord$hip may al$o be plea$ed to
remember, That by our $eventeenth Ex-
periment it appear'd that as when the Air
in the Receiver was expanded more then
ordinarily, the Quick-$ilver in the Tube
did proportionably $ub$ide; $o when the
Air in the $ame Receiver was a little more
then ordinarily compre$$'d, it did impell
up the Quick-$ilver in the Tube above
the wonted height of betwixt $ix and $e-
ven and twenty digits.
<p>And if to the$e things we annex, that
for ought we can finde by tryals purpo$e-
ly made, the degree of rarity or den$ity
of the Air, $hut up into our Receiver, does
not $en$ibly alter its temperature as to
cold or heat. It will not, I hope, appear
ab$urd to conceive, That $ince the Air,
included in the Tube, could but very faint-
ly hinder the a$cent of the Quick-$ilver,
or pre$s it downwards, $ince too that inclu-
ded Air could $carce immediately receive
any $en$ible alteration, $ave either by heat
<pb n=140>
or cold. And $ince al$o that according to
the bare den$ity or rarity of the Air in-
cumbent on the $ubjacent Quick-$ilver in
the Ve$$el, that in the Tube was impell'd
more or le$s high; $uch changes happen-
ing in the neighboring part of the out-
ward Air, either by the a$cen$ion of gro$s
or copious exhalations, or by any other
cau$e (of which there may be divers) as
were capable to make con$iderable altera-
tions in the con$i$tence of the Air, as to
rarity and den$ity, <I>may</I> be able propor-
tionably to alter the heighth of the
Quick-$ilver: I rather $ay, that $uch alte-
rations <I>may</I> be, then that they <I>are</I> the
cau$es of our <I>Ph&aelig;nomenon,</I> becau$e I think
it $ufficient, if I have propo$'d conje-
ctures not altogether irrational about a
new My$tery of Nature, touching which,
the chief thing I pretend to, is to give oc-
ca$ion to the Curious to inquire further
into it then I have been yet able to do.
<p>THe $ame Rea$on that mov'd us to
<MARG><I>Experi-
ment</I> 19.</MARG>
conclude, that by the drawing of the
Air out of the Receiver, the Mercury
would de$cend in a Tube $horter then $ix
and twenty digits, induc'd us al$o to ex-
<pb n=141>
pect, that by the $ame means Water
might be brought to $ub$ide in Gla$s
Tubes of a moderate length, though by
the noble Experiment, $aid to have been
accurately made in <I>France</I> by <I>Mon$ieur
Pa$chal,</I> we are informed that a Tube of
no le$s then about two and thirty Foot,
was found requi$ite to make the Experi-
ment <I>De Vacuo</I> $ucceed with Water in-
$tead of Quick-$ilver: $o tall a Cylinder
of that lighter Liquor, being, it $eems,
requi$ite to equal the weight of a Mercu-
rial Cylinder of $ix or $even and twenty
digits, and $urmount the pre$$ure of the
Atmo$phere.
<p>We took then a Tube of Gla$s, Her-
metically $eal'd at one end, of about four
foot in length, and not very $lender: This
at the open end we fill'd with common
Water, and then $topt that end till we
had inverted the Tube, and open'd it be-
neath the $urface of a quantity of the like
Water, contain'd in a $omewhat deep and
$lender Ve$$el. This Ve$$el, with the
Tube in it, was let down into the Recei-
ver, and the Receiver being clo$'d up af-
ter the accu$tom'd manner, the Pump was
$et awork.
<pb n=142>
<p>As much of the event as concerns our
pre$ent purpo$e, was this, That till a con-
$iderable part of the Air was drawn out
of the Receiver, the Tube continu'd top-
full of Water as when it was put in, it be-
ing requi$ite that a great part of the Air
formerly contain'd in the Receiver, $hould
be drawn out, to bring the remaining
Air to an <I>&AElig;quilibrium</I> with $o $hort and
light a Cylinder of Water. But when
once the Water began to fall in the Tube,
then each ex$uction of Air made it de-
$cend a little lower, though nothing near
$o much as the Quick-$ilver at the begin-
ning did in the Experiment formerly men-
tion'd. Nor did there appear $o much
inequality in the $paces tran$mitted by
the Water in its de$cent, as there did in
tho$e ob$erv'd in the fall of the Quick-
$ilver, of which the cau$e will $carce $eem
ab$tru$e to him that $hall duly reflect up-
on what has been already deliver'd. And
whereas we drew down the Quick-$ilver
in the Tube $o far as to bring it within an
Inch of the $urface of the other Quick-
$ilver into which it was to fall; the lowe$t
we were able to draw down the Water
was, by our conjecture, to about a Foot
<pb n=143>
or more above the $urface of that in the
Ve$$el; of which I know not whether it
will be needful to a$$ign $o obvious a cau$e
as that, though the little Air remaining
in the Receiver could not hinder a Cylin-
der of above an Inch high of Quick-$ilver
from $ub$iding; yet it might very well
be able, by its pre$$ure, to countervail the
weight of a Cylinder of a Foot long or
more, of a Liquor $o much le$s ponderous
then Quick-$ilver, as Water is. And in
fine, to conclude our Experiment, when
the Water was drawn down thus low, we
found, that by letting in the outward Air,
it might be immediately impell'd up a-
gain to the higher parts of the Tube.
<p>We will adde no more concerning this
Experiment, $ave that having try'd it in
one of our $mall Receivers, we ob$erv'd,
That upon the fir$t ex$uction of the Air
the Water did u$ually $ub$ide divers In-
ches, and at the $econd (ex$uction) fall
down much lower, $ub$iding $ometimes
near two Foot; as al$o that upon the let-
ting in of the Air from without, the Wa-
ter was impell'd up with very great ce-
lerity.
<pb n=144>
<p>THat the Air has a notable Ela$tical
<MARG><I>Experi-
ment</I> 20.</MARG>
power (whence$oever that proceeds)
we have, I $uppo$e, abundantly evinc'd,
and it begins to be acknowledg'd by the
eminente$t Modern Naturali$ts. But whe-
ther or no there be in Water $o much as
a languid one, $eems hitherto to have been
$carce con$ider'd, nor has been yet, for
ought I know, determin'd either way by
any Writer, which invited us to make the
following Experiment.
<p>There was taken a great Gla$s-bubble,
with a long neck; ($uch as Chymi$ts are
wont to call a Philo$ophical Egg) which
being fill'd with common Water till the
Liquor reach'd about a $pan above the
bubble, and a piece of Paper being there
pa$ted on, was put un$top'd into the Re-
ceiver, and then the Air was $uck'd out
after the wonted manner. The event was
this, That a con$iderable part of the Air,
pent up in the Receiver, was drawn out
before we di$cern'd any expan$ion of the
Water; but, continuing the labor of
pumping, the Water manife$tly began to
a$cend in the $tem of the Gla$s, and di-
vers bubbles loo$ening them$elves from
<pb n=145>
the lower parts of the Ve$$el, made their
way through the Body of the Water, to
the top of it, and there brake into the
Receiver: And after the Water once ap-
pear'd to $well, then at each time the Stop-
cock was turn'd to let out the air from the
Receiver into the Pump, the Water in the
Neck of the Gla$s did $uddenly ri$e a-
bout the breadth of a Barly-corn in the
Neck of the Gla$s, and $o attain'd, by
degrees, to a con$iderable height above
the mark formerly mention'd. And at
length (to make the expan$ion of the Wa-
ter more evident) the outward Air was
$uddenly let in, and the Water immedi-
ately $ub$ided and de$erted all the $pace it
had newly gain'd in the Gla$s.
<p>And, on this occa$ion, it will not per-
haps be ami$s to acquaint Your Lord$hip
here (though we have already mention'd
it in another Paper, to another purpo$e)
with another Expedient that we made u$e
of two or three years ago, to try whether
or no Water had a Spring in it. About
that time then, That Great and Learned
Promoter of Experimental Philo$ophy
Dr. <I>Wilkins,</I> doing me the Honor to
come him$elf, and bring $ome of his in-
qui$itive Friends to my Lodging, we
<pb n=146>
there had in readine$s a round and hollow
Ve$$el of Pewter, great enough to con-
tain two pounds of Water, and exactly
clo$e every where, but at one little hole
where it was to be fill'd; then partly by
$ucking out the Air, and partly by inject-
ing Water with a Syringe, it was (not
without $ome difficulty) fill'd up to the
top; and that hole being plac'd directly
upwards, there was a little more Water
lei$urely forc'd in by the Syringe. Upon
which, though the Ve$$el were permitted
to re$t, and the hole kept in its former po-
$ture, yet the compre$$'d Water lei$urely
$well'd above the Orifice of the hole, and
divers drops ran over along the $ides of the
Ve$$el. After this, we cau$'d a skilful Pew-
terer (who had made the Globe) to clo$e
it up in our pre$ence with Soder $o exqui-
$itely, that none $u$pected there was any
thing left in it be$ides Water. And la$t-
ly, the Ve$$el thus $oder'd up, was wari-
ly and often $truck in divers places with a
Wooden Mallet, and thereby was mani-
fe$tly compre$$ d, whereby the inclo$ed
Water was crouded into le$s room then it
had before: And thereupon when we took
a Needle, and with it and the Mallet per-
forated the Ve$$el, and drew out the
<pb n=147>
Needle again; the Water (but in a very
$lender Stream) was $uddenly thrown af-
ter it into the Air, to the height of two
or three Feet. As for the other <I>Ph&aelig;nome-
na</I> of this Experiment, $ince they belong
not to our pre$ent purpo$e, and are partly
mention'd in another of our Papers, we
$hall, in$tead of recording them here, give
this Adverti$ement: That as evidently
as this Experiment, and that made in our
Receiver, $eem to prove a power in the
Water to expand and re$tore it $elf after
compre$$ion; yet for a rea$on to be met
with ere long, I judged it not $afe to in-
fer that Conclu$ion from the$e Premi$es,
till I had made $ome of the following try-
als, to the mention of which I will there-
fore ha$ten.
<p>TO di$cover whether the Expan$ion
<MARG><I>Experi-
ment</I> 21.</MARG>
of the Water really proceeded
from an Ela$tical power in the parts of
the Water it $elf, we thought it requi$ite
to try two things: The one, Whether or no
the Atmo$phere gravitates upon Bodies
under Water; and the other, Whether
in ca$e it do gravitate, the Intume$cence
of the Water may not be a$cribed to $ome
<pb n=148>
$ub$tance $ubtler then it $elf, re$iding m-
it. In order to the $atisfying my $elf about
the fir$t of the$e, I intended to let down
into the Receiver a Ve$$el of Water,
wherein $hould be immer$'d a very $mall
oyl'd Bladder, almo$t devoid of Air, but
$trongly <*>'d up at the Neck with a $tring,
and detain'd a little under Water by $uch
a weight fa$ten'd to that $tring, as $hould
ju$t be able to keep the Bladder from
$wimming, and no more. For I $uppo$'d,
that if when all things were thus order'd,
the Receiver were empty'd, in ca$e there
were any $uch pre$$ure of the Atmo$phere
upon Water, as I was inclin'd to believe,
the Air within the Bladder, being upon the
ex$uction of the Air within the Receiver,
freed from that pre$$ure, and being pre$$'d
onely by the $mall weight of the in-
cumbent Water, would con$iderably ex-
pand it $elf; but whil'$t we were prepa-
ring Bladders for this Experiment, there
occurr'd an ea$ie way for the making at
once both the Di$coveries I de$ir'd.
<p>We took then a Gla$s Viol, containing
by ghe$s a pound and $ome ounces of
Water, this we fill'd top full, and then
we put into the Neck of it a Gla$s Pipe
a pretty deal bigger then a Goo$e Quill,
<pb n=149>
open at both ends, and of divers Inches
in length: One end of this Pipe was $o
put into the Neck of the Viol, as to reach
a little below it, and then was carefully
cemented thereto that no Air might get
into the Viol, nor no Water get out of
it, otherwi$e then through the Pipe; and
then the Pipe being warily fill'd, about
half way up to the top, with more Wa-
ter, and a mark being pa$ted over again$t
the upper $urface of the Liquor; the Viol
thus fitted with the Pipe, was, by $trings
let down into the Receiver, and according
to the wonted manner exqui$itely clo$'d
up in it.
<p>This done, we began to Pump out the
Air, and when a pretty quantity of it had
been drawn away, the Water in the Pipe
began to ri$e higher in the Pipe, at the
$ides of which $ome little bubbles di$co-
ver'd them$elves. After a little while
longer, the Water $till $welling, there
appear'd at the bottom of the Pipe a bub-
ble about the bigne$s of a $mall Pea,
which a$cending through the Pipe to the
top of the Water, $taid there awhile and
then broke; but the Pump being nimbly
ply'd, the expan$ion of the Water $o en-
crea$'d, that quickly, getting up to the
<pb n=150>
top of the Pipe $ome drops of it be-
gan to run down along the out-$ide of it,
which oblig'd us to forbear pumping a-
while, and give the Water leave to $ub-
$ide within le$s then two Inches of the
bottom of the Pipe. After this the
Pump being again $et at work, the bub-
bles began to a$cend from the bottom
of the Pipe, being not all of a $ize, but yet
$o big, that e$timating one with another,
they appear'd to be of the $ize of the $mal-
ler $ort of Peas; and of the$e we reckon'd
about $ixty which came up one after ano-
ther, be$ides $tore of $maller ones, of which
we made no reckoning: And at length,
growing weary of reckoning and pumping
too (becau$e we found, that in $pight
of all our pains and indu$try, $ome un-
di$cern'd Leak or other in the Recei-
ver hinder'd us from being able to empty
it altogether) we thought fit to de$i$t for
that time. After tryal made of what o-
peration the external Air, being let in
upon the expanded Water, would have;
and accordingly turning the Key to let in
the Air, we $aw, as we expected, that
the Water in the Pipe in a moment fell
down almo$t to the bottom of it.
<pb n=151>
<p>Now of this Experiment there are two
or three Circum$tances yet to be men-
tion'd, which are no le$s then tho$e alrea-
dy recited, pertinent to our pre$ent pur-
po$e.
<p>In the fir$t place then, when the great-
er part of the Air had been pump'd out of
the Receiver, the ri$ing bubbles a$cend-
ed $o very $lowly in the Pipe, that their
Progre$s was $carce di$cernable; which
$eem'd to proceed from this, That their
bigne$s was $uch, That they could not
$ufficiently extend them$elves in the
cavity of the Gla$s, without pre$$ing
on both hands again$t the $ides of it,
whereby they became of more difficult
extru$ion to the Water. And though it
may $eem $trange the$e bubbles $hould
be of any con$iderable bulk, $ince 'tis
like they con$i$ted of le$$er parcels of
the Air lurking in the Water, then tho$e
that were vigorous enough to make their
way through long before them: yet they
were commonly much larger then before,
$ome of them being equal in quantity to
four or five Peas: Whether this their in-
crea$e of bulk proceeded from the greater
decrement of the pre$$ure of the Air,
<pb n=152>
or from the Union of two or three of
tho$e numerous bubbles which were then
generated below the bottom of the Pipe,
where we could not $ee what was done a-
mong them.
<p>Another thing we noted in our bubbles
was, That whereas in ordinary ones the
Air, together with the thin film of Water
that inve$ts and detains, is wont to $well
above the $urface of the Water it $wims
on, and commonly to con$titute Hemi$-
pherical Bodies with it, the little parcels
of Air that came up after the Receiver
was pretty well empty'd, did not make
protuberant bubbles, but $uch who$e up-
per $urface was either level with or be-
neath that of the Water, $o that the up-
per $urface being u$ually $omewhat con-
vex, the le$s protuberant parts of it had
a pretty quantity of Water remaining a-
bove them.
<p>We al$o further ob$erv'd, That where-
as in the bubbles that fir$t appear'd in
the Pipe, the a$cending Air did, as in o-
ther common bubbles, make its way up-
wards, by dividing the Water through
which it pa$$'d, in tho$e bubbles that ap-
pear'd at the latter end of our Experi-
ment, when the pre$$ure of the little ex-
<pb n=153>
ternal Air, remaining in the Receiver,
was grown incon$iderable, the a$cending
parcels of Air having now little more
then the weight of the incumbent Water
to $urmount, were able both $o to expand
them$elves as to fill up that part of the
Pipe which they pervaded, &amp; by pre$$ing
every way again$t the $ides of it, to lift
upwards with them what Water they
found above them, without letting any
con$iderable quantity glide down along
the $ides of the Gla$s: So that $ometimes
we could $ee a bubble thru$t on before it
a whole Cylinder of Water of perhaps
an Inch high, and carry it up to the top
of the Pipe; though as we formerly no-
ted, upon the letting in the external Air,
the$e tumid bubbles $uddenly relap$'d to
their former incon$picuou$ne$s.
<p>All the$e things laid together $eem'd
$ufficiently to confirm that, which the
con$ideration of the thing it $elf would
ea$ily enough per$wade, namely, That
the Air, and $uch like Bodies being under
Water, may be pre$$'d upon as well by
the Atmo$phere, as by the weight of the
incumbent Water it $elf.
<p>Hence likewi$e we may verifie what we
ob$erv'd at the clo$e of the foregoing
<pb n=154>
Experiment, namely, That from the $ole
$welling of Water there recorded, it can-
not be $o $afely concluded that Water,
when freed from compre$$ion, is endowd
with an Ela$tical power of expanding it
$elf, $ince thereby it appears that the In-
tume$cence produc'd by that Experiment,
may (at lea$t in great part) be a$crib'd to
the numerous little bubbles which are
wont to be produc'd in Water, from
which the pre$$ure of the Atmo$phere is
in great mea$ure taken off. So apt are we
to be mi$-led, even by Experiments them-
$elves, into Mi$takes, when either we con-
$ider not that mo$t Effects may proceed
from various Cau$es, or minde onely tho$e
Circum$tances of our Experiment, which
$eem to comply with our preconceiv'd
<I>Hypothe$is</I> or Conjectures.
<p>And hence it $eems al$o probable, that
in the Pores or invi$ible little rece$$es of
Water it $elf there lie commonly inter-
$per$'d many parcels of either Air, or at
lea$t $omething Analogous thereunto, al-
though $o very $mall that they have not
been hitherto $o much as $u$pected to
lurk there. But if it be demanded how it
appears that there is inter$per$'d through
the Body of Water any $ub$tance thinner
<pb n=155>
then it $elf, and why that which produc'd
the bubbles above mention'd $hould not
be re$olutely $aid to be nothing el$e then
a more active and $pirituous part of the
Water, we $hall, in order to the Elucida-
tion of this matter, $ubjoyn to what
was formerly deliver'd the following Ex-
periment.
<p>WE recited in our nineteenth Ex-
periment, how by drawing mo$t
<MARG><I>Experi-
ment</I> 22.</MARG>
of the Air out of the Receiver, we made
the Water $ub$ide by degrees in a Gla$s
not four Foot long: We $hall now adde,
that in the like Experiment made in $uch
a Tube, or a greater, it may be ob$erv'd,
That when the Water begins to fall, there
will appear $tore of bubbles fa$ten'd all a-
long to the $ides of the Gla$s; of which
bubbles, by the agitation of the Ve$$el
con$equent upon pumping, there will ari$e
good numbers to the top of the Water,
and there break; and as the Cylinder of
Water is brought to be lower and lower,
$o the bubbles will appear more numerous
in that part of the Tube which the Water
yet fills; and the nearer the $urface of the
Water, in its de$cent, approaches to the$e
<pb n=156>
bubbles, the greater they will grow, be-
cau$e having the le$s weight and pre$$ure
upon them, the Expan$ion of that Air
which makes them, can be the le$s re$i$ted
by the pre$$ure of the incumbent Water
and Air; as $eems probable from hence,
that upon the letting in a little external
Air, tho$e bubbles immediately $hrink.
<p>It may indeed, as we lately intimated,
be conjectur'd, that the$e bubbles pro-
ceed not $o much from any Air pre-exi-
$tent in the Water, and lurking in the
Pores of it, as from the more $ubtle parts
of the Water it $elf; which by the expan-
$ion allow'd them upon the dimini$h'd
pre$$ure of the ambient Bodies may gene-
rate $uch bubbles. And indeed, I am not
yet $o well $atisfied that bubbles may not
(at lea$t $ometimes) have $uch an Origina-
tion: but that which makes me $u$pect
that tho$e in our tryals contain'd real Air
formerly latitant in the Pores of the Wa-
ter, is this, That upon the inletting of
the external Air, the Water was not
again impell'd to the very top of the
Tube whence it began to fall, but was
$topt in its a$cent near an Inch beneath
the top. And $ince, if the upper part of
the Tube had been devoyd of any other
<pb n=157>
then $uch Ethereal matter as was $ubtle
enough freely to penetrate the pores of
the Gla$s, the external Air would have
been able to impel the Water to the top
of a Tube $even or eight times as long as
ours was; The <I>Ph&aelig;nomenon</I> under con$i-
deration $eem'd manife$tly to argue that
the many bubbles that broke at the top
of the Water did contain a real Air,
which, being collected into one place and
hinder'd by the top of the Gla$s from re-
ceding, was able to with$tand the pre$$ure
of the outward Air. As we $ee that if
never $o little Air remain in the Tube up-
on the making the Experiment <I>De Vacuo</I>
with Quick-$ilver, no inclining of the
Tube, though a long one, will enable a
Man to impel the Mercury up to the very
top, by rea$on (as we formerly noted)
of the re$i$tance of the included Air, which
will not be compre$$'d beyond a certain
degree.
<p>But in order to a further Di$covery what
our bubbles were, we will, on this occa-
$ion, inform Your Lord$hip that we try'd
the XIX<SUP>th</SUP> <I>Experiment</I> in one of our $mall
Receivers, and $ound, that upon the draw-
ing down of the Water, $o many bubbles
di$clo$'d them$elves and broke into the
<pb n=158>
upper part of the Tube, that having after-
wards let in the external Air, the Water
was not thereby impell'd to the top of the
Tube (three Foot in length) within a lit-
tle more then half an Inch. And whe-
ther or no it were Air that po$$e$$'d that
$pace at the top of the Tube which was
not fill'd with Water, we took this cour$e
to examine. We drew the $econd time
the Air out of the Receiver, and found,
that by rea$on of the body that po$$e$$'d
the top of the Tube, we were able not
onely to make the Water in the Tube fall
to a level with the $urface of the Water
in the Ve$$el: But al$o (by plying the
Pump a little longer) a great way beneath
it: which $ince it could not well be a$crib'd
to the bare $ub$iding of the Water by rea-
$on of its own weight, argued that the Wa-
ter was depre$$'d by the Air: which was
confirm'd by the Figure of the $urface of
the Water in the Tube, which was much
more concave then that of Water in
Tubes of that bigne$s u$es to be. And
this further tryal (to adde that upon
the by) we made at the $ame time, That
when the Water in the Pipe was drawn
down almo$t as low as the Water without
it, we ob$erv'd, that (though we de$i$ted
<pb n=159>
from pumping) by the bare application
of a hand moderately warm to the de$ert-
ed part of the Tube, the remaining Wa-
ter would be $peedily and notably de-
pre$$'d. And having for a while held a
kindled Coal to the out$ide of the Tube,
(the Pump being $till unimploy'd, becau$e
the Ve$$el chanced to hold extraordinarily
well) the Air was by the heat $o far ex-
panded, that it quickly drave the Water
to the bottom of the Tube, which was
divers Inches beneath the $urface of the
ambient Water. Whereby it appears (by
the $ame way by which we formerly mea-
$ur'd the dilatation of the Air) that the
Air, even when it is expanded to between
90 and 100 times, its extent will yet rea-
dily admit of a much further rarifaction
by heat.
<p>I con$ider'd al$o that in ca$e the Bub-
bles we have been $peaking of, were pro-
duc'd by the parcels of Air latitant in the
Water, that Air being now got together
to the top of the Tube, though the Air
were again drawn out of the Receiver,
the taking off its pre$$ure would not di$-
clo$e bubbles as before; and accordingly,
the Air being again pump'd out, the Wa-
ter in the Tube de$cended as formerly:
<pb n=160>
but for a great while we $carce $aw one
bubble appear, onely when the Receiver
had been very much exhau$ted, and the
Water was fallen very low, there appear'd
near the bottom of the Tube, certain
little bubbles, which $eem'd to con$i$t of
$uch parcels of Air as had not, by rea$on
of their $malne$s, got up to the top of
the Water, with the more bulkie and vi-
gorous ones. And that which is not in-
con$iderable, is, That having, by letting
in the Air, forc'd up the Water into the
Tube, we could not perceive that it a$-
cended nearer the top, though we per-
mitted the Engine to remain unimploy'd
for two or three Nights together, and
watch'd whether the Water would $well
up and fill the Tube. And on this occa-
$ion I remember, that having try'd $uch an
Experiment as this with Quick-$ilver in-
$tead of Water, in a Tube of about a Foot
and a half long, wherein it might $eem
more hopeful to e$cape bubbles; yet up-
on the drawing down the Quick-$ilver as
low as we could, and letting in the exter-
nal Air upon it, we found that $ome lurk-
ing particles of Air were got up to the top
of the Tube, and hinder'd the Quick-
$ilver from being forc'd up again $o high.
<pb n=161>
And though the Quick-$ilver were by
this means brought to appear a very clo$e
and lovely Metalline Cylinder, not inter-
rupted by inter$per$'d bubbles as before;
yet having cau$'d the Air to be again
drawn out of the Receiver, I could per-
ceive $everal little bubbles to di$clo$e
them$elves, fa$ten'd to the in$ide of the
Tube, near the bottom of it; and having
purpo$ely watch'd one or two of the chief-
e$t, I had the plea$ure to ob$erve, that
though they grew bigger and bigger as
the $urface of the Mercurial Cylinder fell
nearer and nearer to them, $o as that at
length they $well'd into a con$picuous
bulk; yet upon the wary letting in the
Air upon them, they did not break, but
pre$ently $hrunk up into a littlene$s that
render'd them incon$picuous.
<p>Whence it $eems very probable, if not
certain, that even in the clo$e$t and mo$t
ponderous Liquors, and therefore much
more in Water, there may lurk undi$cern-
able parcels of Air, capable, upon the
removal of the pre$$ure of the ambient
Air (though but in part) and that of the
Liquor wherein it lurks, to produce con-
$picuous bubbles. And con$equently, if
it $eem inconvenient to admit an Ela$tical
<pb n=162>
power in the Water, it may be $aid that
the $welling of the compre$$'d Water in
the Pewter Ve$$el lately mention'd, and
the $pringing up of the Water at the hole
made by the Needle, were not the effects
of any internal <I>Elater</I> of the Water, but
of the $pring of the many little particles
of Air di$per$'d through that Water, and
acting upon it in their $udden recovering
them$elves to a greater extent, then that
to which a violent compre$$ion had re-
duc'd them.
<p>But though, from all the$e particulars,
it $eems manife$t that the bubbles we have
been all this while treating of, were pro-
duc'd by $uch a $ub$tance as may be pro-
perly enough call'd Air; yet till we $hall
have had the opportunity of making
$ome further tryals concerning the nature
of the Air, we $hall not re$olutely deter-
mine whether or no Air be a Primogenial
Body (if I may $o $peak) that cannot
now be generated or turn'd either into
Water or any other Body. Yet in the
mean while (becau$e it is an important
Que$tion, and if rightly determin'd, may
much conduce to the knowledge of the
<pb n=163>
nature of the Air) We think it not unfit
to make a brief mention of $ome of the
particulars which at pre$ent occur to our
thoughts in favor of either part of the
Que$tion.
<p>Fir$t then, divers Naturali$ts e$teem the
Air (as well as other Elements) to be in-
generable and incorruptible. And rea$ons
plau$ible enough may be drawn to coun-
tenance this Opinion from the con$idera-
tion of that permanency that ought to
belong to the corporeal Principles of o-
ther Bodies.
<p>Next, Experience may be pleaded to
the $ame purpo$e, for I have read of $ome
who have in vain attempted to turn Air
into Water, or VVater into Air.
<p>The diligent <I>Schottus</I> tells us, That a-
<MARG><I>Schottus
<*></I>
Part 3.
Cla$$. 1.</MARG>
mong$t the other rarities to be met with
in that great Repo$itory of them, the
<I>Mu$&aelig;um Kercherianum,</I> there is a round
Gla$s with a tapering Neck near half full
(as one may gue$s by the Scheme he an-
nexes) of ordinary Spring-water, which
having been Hermetically $hut up there
by <I>Clavius</I> the famous Geometrician,
The included water is to this day pre-
$erv'd, not onely clear and pure, as if
it were but newly put in: But (as it $eems)
<pb n=164>
without (in the lea$t) turning into Air,
notwith$tanding its having been kept
there the$e fifty years: For he tells us,
That the Water hath continued there all
this while without any diminution.
<p>Nor does it appear in tho$e Gla$$es,
which for Chymical Experiments we u$u-
ally clo$e with <I>Hermes</I> his Seal (as they
call it) that the included Air does, during
its long Impri$onment, notwith$tanding
the alteration it receives from various de-
grees of heat, di$cernably alter its nature.
Whereas we plainly perceive in our Dige-
$tions and Di$tillations, that though it
may be rarified into invi$ible Vapors, yet
it is not really chang'd into Air, but onely
divided by heat, and $catter'd into very
minute parts, which meeting together in
the Alembick or in the Receiver, do pre-
$ently return into $uch Water as they con-
$tituted before. And we al$o $ee, that
ev'n Spirit of Wine, and other $ubtle and
fugitive Spirits, though they ea$ily fly in-
to the Air, and mingle with it, do yet in
the Gla$$es of Chymi$ts ea$ily lay a$ide
the di$gui$e of Air, and re$ume the deve-
$ted form of Liquors. And $o volatile
Salts, as of Urine, Harts-horn, <I>&amp;c.</I> though
they will readily di$per$e them$elves
<pb n=165>
through the Air, and play up and down in
the capacity of an Alembick or a Recei-
ver: yet will they, after a while, fa$ten
them$elves to the in$ides of $uch Gla$$es
in the form of Salts.
<p>Be$ides, $ince Air is confe$$edly en-
dow'd with an Ela$tical power that proba-
bly proceeds from its Texture, it appears
not what it is that in $uch light alterations
of Water, as are by many pre$um'd ca-
pable of turning it into Air, can be rea-
$onably $uppo$'d $o to contrive the Parti-
cles of Water, as to give them, and that
permanently, the $tructure requi$ite to a
Spring. I adde the word, Permanently,
becau$e the newly mention'd ob$ervations
$eem to argue the Corpu$cles of Air to
be irreducible into Water, whereas the
Aqueous Particles may perhaps for a
while be $o vehemently agitated, as to
pre$s almo$t like Springs upon other Bo-
dies; yet upon the cea$ing of the agitati-
on, they quickly, by relap$ing into Wa-
ter, di$clo$e them$elves to have been no-
thing el$e whil'$t they counterfeited the
Air.
<p>La$tly, The Experiment formerly made
in our Engine with a piece of Match,
$eems to evince, that even tho$e light and
<pb n=166>
$ubtle Fumes (for the mo$t part not aque-
ous neither) into which the Fire it $elf
$hatters dry Bodies, have no $uch Spring
in them as the Air, $ince they were unable
to hinder or repre$s the expan$ion of the
Air included in the Bladder they $urroun-
ded.
<p>I remember indeed that the Learned
<MARG><I>Natural &amp;
<*> Hi$t.
<*> In-
<*>,</I> Lib. 3.
<*> 9.</MARG>
<I>Fo$ephus Aco$ta,</I> in his Hi$tory of the
<I>We$t Indies,</I> tells us, That he $aw in tho$e
parts $ome Grates of Iron $o ru$ted and
con$um'd by the Air, that the Metal be-
ing pre$$'d between the Fingers, di$$olv'd
(to u$e his words) to powder, as if it had
been Hay or parched Straw. And I re-
<MARG><I>Geogr. Ge-
<*>ral.</I> Lib.
<*> 19.</MARG>
member too, that the accurate <I>Varenius</I>
tells us, That in the I$lands commonly
called <I>Azores,</I> the Air (and Wind) is $o
$harp, that in a $hort time it frets not only
Iron Plates, but the very Tiles upon the
Roofs of Hou$es, and reduces them to
du$t. And I have el$ewhere mention'd
$ome recent Ob$ervations of this kinde.
But it may be $aid, That the above-men-
tion'd Authors a$cribe the recited effects
chiefly to the Winds, and that however
the corro$ion of the Iron and the Tiles
may proceed not from the Air it $elf, or
any of its genuine parts, but from $ome
<pb n=167>
$aline Corpu$cles di$per$'d through the
Air, and driven by the Winds again$t the
Bodies it is pre$um'd to fret. And that
$uch volatile Salts may copiou$ly a$cend
into the Air, and yet retain their Nature,
as doth the more fixt Salt in the Sea Wa-
ter, the $ublimations of <I>Sal-Armoniack</I>
may $ufficiently evince. Not to mention
that I have $hown $ome Friends a $ecret
kinde of $aline Sub$tance incomparably
$ubtler then <I>Sal-Armoniack,</I> which did
not onely ea$ily enough a$cend it $elf, but
carried up with it (and that in a very great
proportion) the $olid and ponderous Bo-
dy ev'n of uncalcin'd Gold in the form of
$ubtle exhalations, which did afterwards
fa$ten them$elves to the upper parts of
the Ve$$els, and yet manife$t them$elves
to continue Gold. We remember al$o,
that to try whether Water could be turn'd
into Air, we once took an <I>&AElig;olipile,</I> into
which we had before convey'd $ome Wa-
ter, and placing it upon kindled Coals
when the heat forc'd out a vehement
$tream of aqueous Vapors; we ty'd about
the neck of it, that of a Bladder, which
we had before empty'd of Air; and find-
ing the <I>&AElig;olipile</I> after a while to blow up
the Bladder, we carefully ty'd it again
<pb n=168>
that the included $ub$tance might not get
away. Then $lipping it off from the <I>&AElig;o-
lipile</I> we convey'd it into our Receiver, to
try whether or no that which in part di-
$tended the Bladder would appear by its
Spring to be true Air: whereby we found
that upon the ex$uction of the ambient
Air, the included $ub$tance expanded it
$elf and the Bladder to a very much great-
er bulk then it was of before. And for
further $atisfaction, having again taken
out the Bladder, we $uffer'd it to remain
ty'd up till next morning, to try whether
time, and the coldne$s of the night, would
make the contain'd $ub$tance relap$e in-
to Water: But the next Morning we
found it little le$s tumid then before. I
remember, I $ay, that I once made this
Experiment; but I might $ay in an$wer
to it, that the chief rea$on of my men-
tioning it, is, To let Your Lord$hip $ee
how requi$ite it is to be circum$pect and
con$iderate, when we are to make and to
build upon nice Experiments. For though
I may $eem to have u$ed $ufficient cauti-
on, yet afterward con$idering with my
$elf that the <I>&AElig;olipile</I> I had imploy'd was
a very large one, and that it required much
more care then one that has not try'd it
<pb n=169>
would imagine, to drive out all the Air
from a large <I>&AElig;olipile,</I> I ea$ily $u$pected
that the di$ten$ion of the Bladder in our
pneumatical Ve$$el, might proceed not
from the Watery $teams that came out at
the narrow mouth of the <I>&AElig;olipile,</I> and
had very much wetted the Bladder, but
from the rarified Air which in that $ort of
Ve$$els is wont for a good while together
to come out with the rarified Water: and
accordingly having reiterated the Experi-
ment I found it very difficult (by rea-
$on of the $hrinking of the Bladders (up-
on their being heated) and of other impe-
diments) to make it $o accurately as to de-
duce from it, that Water may be rarified
into true Air.
<p>Again$t the four other above-mention'd
Con$iderations, we cannot $pend time to
frame Objections, but mu$t forth with
proceed to the mention of tho$e things
that $eem to argue that Air (at lea$t $uch
as produc'd our bubbles) maybe gene-
rated of Water and other Bodies.
<p>Fir$t then we have found by Experi-
ence that a vapid Air, or Water rarified
into vapor, may at lea$t for a while emu-
late the ela$tical power of that which is
generally acknowledg'd to be true Air.
<pb n=170>
For if you take a good <I>&AElig;olipile,</I> with a
moderately $trong and $lender Neck, and
filling it with Water, lay it upon quick
Coals, you may after a while ob$erve $o
great a pre$$ure by $ome of the parts con-
tain'd in the <I>&AElig;olipile</I> upon others, that
the Water will $ometimes be thrown up
into the Air above three or four Foot
high; and if you then take the <I>&AElig;olipile</I>
almo$t red hot from off the Fire, you may
perceive that the Water will for a longer
time then one would ea$ily imagine con-
tinue to be $pouted out in a violent
Stream. And if there remains but little
Water in the <I>&AElig;olipile</I> when tis taken ve-
ry hot from the Fire, immerfing the
Neck of it into cold Water, you will
finde, that after it begins to $uck in $ome
Water, there will be made from time to
time $tore of large bubbles in that Water
where into the neck was plunged. Which
bubbles $eem manife$tly to proceed from
hence, that for a while the heat in the <I>&AElig;-
olipile</I> continues $trong enough to rarifie
part of the Water that is $uck'd in, and
expel it in the form of Vapors through
the Water incumbent on the Pipe. If al-
$o when the <I>&AElig;olipile</I> is almo$t full of wa-
ter, and therefore can contain but little
<pb n=171>
Air; you hold a Coal or Brand in that
$tream of Vapors that i$$ues out of the
narrow mouth of it, you will finde this
vapid or rorid Air, (if I may $o call it)
to blow the Fire very $trongly and with a
roaring noi$e. And that it be not $aid
that 'tis by the external Air which the a-
queous $teams drive before them, and
not by the Steams them$elves, that the
Bla$t is made and the Flame excited; it
has been ob$erv'd, that by approaching
the Coal or Brand almo$t to the mouth
of the <I>&AElig;olipile,</I> the winde appear'd more
vehement then if the Body to be kindled
were held $ome Inches off.
<p>But in regard the ela$tical power of the
Stream, i$$uing out of an <I>&AElig;olipile,</I> $eems
manife$tly due to the heat that expands
and agitates the aqueous Particles where-
of that Stream con$i$ts, and that $uch
rapid winds $eem to be but water $catter'd
into little parts and $et a moving; $ince
we finde, that holding a Knife, or any
$olid, $mooth and clo$e Body again$t the
$tream that i$$ues out of the &AElig;olipile, the
vapors conden$ing upon it, will pre$ently
cover it with water: It will be very per-
tinent to $ubjoyn a notable Experiment
that I remember I have met with in the
<pb n=172>
de$cription given us by the Indu$trious
<I>Kircher,</I> of $everal Mu$ical Engines. And
(though it may $eem $omewhat prolix)
we will recite what he delivers in his own
words, which are the$e.
<p><I>Cum codem tempore quo h&aelig;c $crip$i</I>
<MARG><I><*>: Art:
Mag: Cun:
&amp; Di$$on:
<*>.</I> 9.
<*> 309.</MARG>
<I>$ummi Pont: Innocentii</I> X<SUP>mi</SUP> <I>mandato or-
gani hydraulici in horto Quirinali con$ti-
tuendi cur a mihi commendata e$$et; &AElig;oliam
camer am in$igni $ane $ucce$$u con$trui ju$si-
mus, e&aacute; qu&aelig; $equitur ratione.</I>
<p><I>Erat longitudo $ive altitudo camer&aelig;</I> AH
5 <I>Pedum, Latitudine</I> 3 <I>fere ex lateribus</I>
<MARG><I>See the fif-
<*> Fi-
gure,</I></MARG>
<I>con$tructa; in medio duo tenebat Diaphrag-
mata</I> CD <I>&amp;</I> EJ <I>in modum cribri pluri-
bus for aminibus pertu$a. Paulo infra ca-
nalis</I> G <I>aquam advehens in$erebatur in</I> H
<I>eidem epi$tomium par ab at exitum. Aqua
it &aacute;que per canalem</I> G <I>maximo impetu ruens
vehementi$simum ventum mox intus exci-
t ab at; qui ventus nimia humiditate imbu-
tus, ut purior exiret $iccior&queacute;, Diaphrag-
mata ill a in cribri modum pertu$a, or dinata
$unt. Intra h&aelig;c enim aqu&aelig; vehemens agi-
tatio rupta fracta&queacute; aerem puriorem per</I> A
<I>canalem $ubtilioremque emittebat: Verum
cum po$tea invent&utilde; $it aer&etilde; plus &aelig;quo humi-
d&utilde; interioribus Organi meatibus maxim&utilde;
detrimentum inferre: Hinc ut aer aquo$us</I>
<pb n=173>
<I>$icci$simam c&otilde;$i$tentiam acquireret, ordina-
vimus canalem plumbeum</I> QR <I>in helicem
contortum va$i</I> S <I>aliquantulum capaciori in
modum Urn&aelig; efformato, in$ertum. Intra
urnam enim plumbeam &amp; canalem tortuo-
$um illi$us aer humidus, it a ab omni aquo$i-
tate def&aelig;cabatur, ut ex furno in Organum
derivatus dici potuerit. Urna</I> S <I>canalis
tortuo$us</I> QR <I>ultimum orificium</I> Q <I>in$e-
ritur anemothec&aelig; organi. Et hunc modum
organis hydraulicis omni&utilde; apti$sim&utilde; reperi.</I>
<p><I>Debet autem camer&aelig; illa $ituari in loco
quantum fieri pote$t $icciori it a ut longo ca-
nali aqua intr a eam derivetur ne locus hu-
miditate $ua Organis officiat.</I>
<p>Thus far the Ingenious <I>Kircherus,</I> whom
I the rather cite, becau$e although I have
been informed of divers Ventiducts (as
they call them) by very knowing Tra-
vellers that have ob$erv'd them: Yet this
relation of our Author being very pun-
ctual, and deliver'd upon his own particu-
lar Experience, has, I confe$s, made me
wi$h I had had the good fortune when I
was at <I>Rome,</I> to take notice of the$e Or-
gans; or that I had now the opportunity
of examining of $uch an Experiment.
For if upon a $trict inquiry I $hould find
that the breath that blows the Organs
<pb n=174>
does not really upon the cea$ing of its un-
u$ual agitation by little and little relap$e
into water, I $hould $trongly $u$pect that
'tis po$$ible for Water to be ea$ily turn'd
into Air. I remember indeed, that we
have formerly taught that there lurks an
inter$per$ed Air in the pores of ordinary
Water, which may po$$ibly be $truck out
by the breaking of the Water in its fall
into the &AElig;olian Chamber, (as he calls it.)
But in regard the Scheme $eems to repre-
$ent that Chamber as clo$ely $hut, and
thereby forbids us to $uppo$e that any Air
is carried into it but what is latitant in the
Water, it will $carce $eem probable to
him who remembers how $mall a propor-
tion of Air, that appear'd to be when its
rarification $ea$ed, which was conceal'd in
the Water we freed from bubbles in our
Receiver, that $o little Air as is common-
ly di$per$'d through Water, $hould be a-
ble, in $o little Water as was requi$ite for
$o $mall a room, to make $o vehement a
Wind as our Author here tells us of. I
have $ometime therefore $u$pected, that
in this ca$e the Wind may be produc'd by
$mall particles of the water it $elf, forci-
bly expell'd out of the Chamber into the
Organs. And to the Objection to which
<pb n=175>
I fore$aw this ghe$s to be liable, namely,
That, no heat intervening, there appear'd
nothing that $hould rai$e the Water into
exhalations and give them an impul$e. I
thought it might be $aid that motion a-
lone, if vehement enough, may, with-
out $en$ible heat, $uffice to break Water
into very minute parts, and make them a$-
cend upwards, if they can no where el$e
more ea$ily continue their agitation. For
Iremember, that Travelling betwixt <I>Ly-
ons</I> and <I>Geneva,</I> I $aw, not very far out of
the Way, a place where the River of
<I>Rhone</I> coming $uddenly to be $treighten'd
betwixt two Rocks, $o near each other,
that a Man may (if my Memory fail me
not) $tand a$tride upon both at once: that
rapid Stream da$hing with great impetuo-
$ity again$t its Rocky Boundaries, does
break part of its Water into $uch minute
Corpu$cles, and put them into $uch a mo-
tion, that Pa$$engers ob$erve at a good di-
$tance off, as it were a Mi$t ari$ing from
that place, and a$cending a good way up
into the Air. Such, I $ay, was my $u$-
picion touching the Wind we have been
con$idering, but it $eems $omething odde
that aqueous Vapors $hould, like a dry
Wind, pa$s through $o long and tortu-
<pb n=176>
ous a Pipe of Lead, as that de$crib'd by
our Author, $ince we $ee in the Heads of
Stills, and the Necks of <I>&AElig;olipiles,</I> how
quickly $uch vapors are even by a very lit-
tle cold reconden$ed into Water. But
to this al$o $omething may be $peciou$ly
reply'd; wherefore contenting my $elf to
have mention'd our Authors Experiment
as a plau$ible, though not demon$trative
proof, that Water may be tran$muted in-
to Air. We will pa$s on to mention in
the third place another Experiment, which
we try'd in order to the $ame enquiry.
<p>We took a clear Gla$s bubble (capable
of containing by ghe$s about three Oun-
ces of Water) with a Neck $omewhat
long and wide, of a Cylindrical form;
this we fill'd with Oyl of Vitriol and fair
water, of each almo$t a like quantity, and
ca$ting in half a dozen $mall Iron Nails,
we $topt the mouth of the Gla$s (which
was top-full of Liquor) with a flat piece
of <I>Diapalma</I> provided for the purpo$e,
that accommodating it $elf to the $urface
of the water, the Air might be exqui-
$itely excluded: and $peedily inverting
the Viol, we put the Neck of it into a
$mall wide-mouth'd Gla$s that $tood rea-
dy with more of the $ame Liquor in it, to
<pb n=177>
receive it. As $oon as the neck had reach'd
the bottom of the Liquor it was dipp'd
into, there appear'd at the upper part
(which was before the bottom) of the
Viol a bubble, of about the bigne$s of
a Pea, which $eem'd rather to con$i$t of
$mall and recent bubbles, produc'd by the
action of the di$$olving Liquor upon the
Iron, then any parcel of the external Air
that might be $u$pected to have got in
upon the inver$ion of the Gla$s, e$peci-
ally $ince we gave time to tho$e little
Particles of Air which were carried down
with the Nails into the Liquor to fly up
again. But whence this fir$t bubble was
produced, is not $o material to our Expe-
riment, in regard it was $o $mall: For
$oon after we perceiv'd the bubbles
produced by the action of the <I>Men-
$truum,</I> upon the Metal a$cending co-
piou$ly to the bubble already named, and
breaking into it, did $oon exceedingly in-
crea$e it, and by degrees depre$s the wa-
ter lower and lower, till at length the $ub-
$tance contain'd in the$e bubbles po$$e$$ed
the whole cavity of the Gla$s Viol, and
almo$t of its Neck too, reaching much
lower in the Neck then the $urface of the
ambient Liquor, wherewith the open-
mouth'd Gla$s was by this means almo$t
<pb n=178>
repleni$hed. And becau$e it might be
$u$pected that the depre$$ion of the Li-
quor might proceed from the agitation
whereinto the exhaling and impri$on'd
$teams were put, by that heat which is
wont to re$ult from that action of corro-
$ive $alts upon Metals, we $uffered both
the Viol and the open-mouthed Gla$s to
remain as they were, in a Window, for
three or four days and nights together; but
looking upou them $everal times during
that while, as well as at the expiration of
it, the whole cavity of the Gla$s bubble,
and mo$t of its Neck, $eem'd to be po$-
$e$$'d by Air, $ince by its $pring it was a-
ble for $o long to hinder the expell'd and
ambient Liquor from regaining its former
place. And it was remarkable, that ju$t
before we took the Gla$s bubble out of
the other Gla$s, upon the application
of a warm hand to the convex part of the
bubble; the Impri$on'd $ub$tance readily
dilated it $elf like Air, and broke through
the Liquor in divers bubbles, $ucceeding
one another.
<p>Having al$o another time try'd the like
Experiment with a $mall Viol, and with
Nails di$$olv'd in <I>Aquafortis,</I> we found
nothing incongruous to what we have
now deliver'd. And this Circum$tance
<pb n=179>
we ob$erv'd, that the newly generated
$teams did not onely po$$e$s almo$t all the
whole cavity of the Gla$s, but divers
times without the a$$i$tance of the heat of
my hand, broke away in large bubbles
through the ambient Liquor into the o-
pen Air: So that the$e Experiments
with corro$ive Liquors, $eem'd manife$t-
ly enough to prove, though not that Air
may be generated out of the Water, yet
that in general air may be generated anew.
<p>La$tly, to the foregoing Arguments
from Experience we might ea$ily $ubjoyn
the Authority of <I>Ari$totle,</I> and of (his
followers) the Schools who are known to
have taught, that Air and Water being
Symbolizing Elements (in the quality of
moi$ture) are ea$ily tran$mutable into one
another. But we $hall rather to the fore-
going Argument adde this, drawn from
Rea$on, That if, as <I>Leucippus, Democri-
tus, Epieurus</I> and others, follow'd by
divers modern Naturali$ts, have taught,
the difference of Bodies proceeds but
from the various Magnitudes, Figures,
Motions, and Textures of the $mall
parts they con$i$t of, (all the quali-
ties that make them differ, being de-
ducible from thence) there appeares
<pb n=180>
no rea$on why the minute parts of Wa-
ter, and other Bodies, may not be $o agi-
tated or connected as to de$erve the name
of Air. For if we allow the <I>Carte$ian
Hypothe$is,</I> according to which, as we no-
ted at the beginning of this Letter, the
Air may con$i$t of any terrene or aqueous
Corpu$cles, provided they be kept $wim-
ming in the interfluent Cele$tial Matter;
it is obvious that Air may be as often ge-
nerated, as Terre$trial Particles minute
enough to be carried up and down, by the
Cele$tial Matter a$cend into the Atmo-
$phere. And if we will have the Air to
be a <I>congeries</I> of little $lender Springs, it
$eems not impo$$ible, though it be diffi-
cult, that the $mall parts of divers Bo-
dies may by a lucky concour$e of cau$es
be $o connected as to con$titute $uch
little Springs, $ince (as we note in another
Treati$e) Water in the Plants it nouri$hes
is u$ually contriv'd into Springy Bodies,
and even the bare alter'd po$ition and con-
nexion of the parts of a Body may $uf-
fice to give it a Spring that it had not be-
fore, as may be $een in a thin and fiexible
Plate of Silver; unto which, by $ome
$troaks of a Hammer, you may give a
Spring, and by onely heating it red hot
<pb n=181>
you may make it again flexible as be-
fore.
<p>The$e, My Lord, are $ome of the
Con$iderations at pre$ent occurring to
my thoughts, by which it may be made
probable that Air may be generated a-
new. And though it be not impo$$ible
to propo$e Objections again$t the$e, as
well as again$t what has been repre$ented
in favor of the contrary Doctrine; yet
having already almo$t tyr'd my $elf, and
I fear more then almo$t tyr'd Your Lord-
$hip with $o trouble$ome an Enquiry af-
ter the Nature of bubbles, I $hall wil-
lingly leave Your Lord$hip to judge of
the Arguments alledged on either $ide,
and I $hould $carce have ventur'd to enter-
tain You $o long concerning $uch empty
things as the Bubbles, which have occa-
$ion'd all this Di$cour$e, but that I am
willing to invite You to take notice with
me of the ob$curity of things, or the dim-
ne$s of our created Intellects (which yet
of late too many $o far pre$ume upon, as
either to Deny or Cen$ure the Almighty
and Omni$cient Creator him$elf) and to
learn hence this Le$$on, That there are
very many Things in Nature that we di$-
dainfully over-look as obvious or de$pi-
<pb n=182>
cable, each of which would exerci$e our
Under$tandings, if not po$e them too, if
we would but attentively enough con$ider
it, and not $uperficially contemplate, but
attempt $atisfactorily to explicate the na-
ture of it.
<p>SInce the writing of the twenty one and
<MARG><I>Experi-
ment</I> 23.</MARG>
twenty $econd Experiments (and not-
with$tanding all that hath been on their
occa$ion deliver'd concerning bubbles) we
made $ome further tryals in pro$ecution
of the $ame inquiry whereto they were
de$igned.
<p>We cho$e then, among$t tho$e Gla$$es
which Chymi$ts are wont to call Philo$o-
phical Eggs, one that containing about
nine Ounces of Water, had a Neck of
half an Inch in Diameter at the top, and
as we ghe$t, almo$t an Inch at the bot-
tom; which breadth we pitch'd upon for
a rea$on that will by and by appear: then
filling it with common Water to the
height of about a Foot and a half, $o
that the upper part remain'd empty, we
$hut it into the Receiver, and watch'd what
would follow upon pumping, which pro-
<pb n=183>
ved that a great part of the Air being
drawn out, the bubbles began to di$cover
them$elves at the bottom and $ides of the
Gla$s; and increa$ing, as the Air was
more and more drawn away, they did
from time to time a$cend copiou$ly e-
nough to the top of the Water, and there
quickly break: but by rea$on that the
widene$s of the Gla$s allow'd them free
pa$$age through the Water, they did not
appear as in the former Experiments to
make it $well: The Water $carce ever ri-
$ing at all above the mark affixt to its up-
per $urface when it was put in, and upon
the return permitted to the outward Air,
and con$equently the $hrinking in of the
remaining bubbles, the Water $eem'd to
have lo$t of its fir$t extent, by the avo-
lation of the formerly inter$per$'d Air.
<p>Being willing likewi$e to try whether
di$tilled Water were by having been di-
vided into minute parts, and then re-uni-
ted, more or le$s di$po$'d to expand it
$elf then Water not di$till'd: We took
out of our Laboratory $ome careful-
ly di$till'd Rain-water, and put about
two Ounces of it into a round Gla$s
<pb n=184>
bubble with a very $mall Neck (not ex-
ceeding the $ixth part of an Inch in Dia-
meter) which we fill'd half way to the
top, and then convey'd it into the Recei-
ver; the i$$ue was, That though we drew
out more then ordinary, yet there ap-
pear'd not the lea$t intume$cence of the
Water, nor any a$cending bubbles.
<p>But $u$pecting that either the $mall
quantity of the water or the Figure of the
Ve$$el might have an intere$t in this odde
<I>Ph&aelig;nomenon,</I> we took the lately mention'd
Philo$ophical Egge, and another not
much differing from it; the former we
fill'd up with di$till'd Rain-water to the
old mark, and into the latter we put a
long Cylinder or Rod of $olid Gla$s to
$treighten the cavity of the Neck by al-
mo$t filling it up; and then pouring $ome
di$tilled Water into that al$o, till it
reach'd within $ome Fingers breadth of
the top, the Eggs were let down into the
Receiver. In this Experiment the Air
was $o far drawn forth before there ap-
pear'd any bubble in either of the Gla$$es,
that the di$parity betwixt this and com-
mon water was manife$t enough. But at
length, when the Air was almo$t quite
pump'd out, the bubbles began to di$-
<pb n=185>
clo$e them$elves, and to increa$e as the
pre$$ure of the Air in the Receiver de-
crea$'d. But whereas in the fir$t men-
tion'd Philo$ophical Egge the bubbles
were very $mall, and never able to $well
the Water, that we took notice of, at all
above the mark: In the other, who$e
Neck, as we lately $aid, was $traightned,
and their pa$$age ob$tructed, great num-
bers of them, and bigger, fa$tned them-
$elves to the lower end of the Gla$s ram-
mer (if we may $o call it) and gather'd in
$uch numbers between that and the $ides
of the Neck, that the Water $well'd a-
bout a Fingers breadth above the mark,
though upon the admitting of the exter-
nal Air it relap$'d to the former mark, or
rather fell $omewhat below it. And al-
though thereupon in the fir$t nam'd Ve$-
$el all the bubbles pre$ently di$-appear'd,
yet in the other we ob$erv'd, that divers
remained fa$tned to the lower part of the
Gla$s rammer, and continued there $ome-
what to our wonder, for above an hour
after, but contracted in their Dimen-
$ions.
<p>Moreover, having $uffered the Gla$$es
to remain above twenty four hours in the
<pb n=186>
Receiver, we afterwards repeated the Ex-
periment, to try what change the ex$ucti-
on of the external Air would produce in
the Water, after the internal and latitant
Air had (as is above recited) in great mea-
$ure got away in bubbles, and whether or
no the Water would by $tanding re-admit
any new particles of Air in the room of
tho$e that had for$aken it. But though
we exhau$ted the Receiver very diligent-
ly, yet we $carce $aw a bubble in either
of the Gla$$es; notwith$tanding which,
we perceiv'd the Water to ri$e about the
breadth of a Barly-corn, or more, in the
Neck of that Gla$s wherein the $olid Cy-
linder had been put; The Liquor in the
other Gla$s not $en$ibly $welling.
<p>And la$tly, upon the letting in of the
Air, the Water in the $traightned Neck
$oon $ub$ided to the mark above which
it had $wollen, which whether it ought
to be a$crib'd to the $ame $mall expan$ion
of the parts of the Water it $elf, or to
the rarifaction of $ome yet latitant Air
broken into $uch $mall particles, as to e-
$cape our ob$ervation, $eems not ea$ily
determinable, without $uch further tryals,
as would perhaps prove tedious to be re-
cited as well as to be made; though I was
<pb n=187>
content to $et down tho$e already men-
tion'd, that it might appear how requi-
$ite it is in nice Experiments to con$ider
variety of Circum$tances.
<p>AFter having thus di$cover'd what ope-
<MARG><I>Experi-
ment</I> 24.</MARG>
ration the ex$uction of the ambient
Air had upon Water, we thought good
to try al$o what changes would happen in
other Liquors upon the like taking off the
pre$$ure of the external Air. We took
then a Gla$s Egge, $omewhat bigger then
a Turkey Egge, which had a long Neck
or Stem of about a 1/3 part of an Inch in
Diameter; and filling it up with Sallet
Oyl until it reach'd above half way to the
top of the Neck, we inclo$'d it in the Re-
ceiver together with common Water in
a re$embling Ve$$el, that we might the
better compare together the operation of
the ex$uction of the Air upon tho$e two
Liquors. The Pump being $et a work there
began to appear bubbles in the Oyl much
$ooner then in the Water, and afterwards
they al$o a$cended much more copiou$ly
in the former Liquor then the latter: Nay,
and when by having quite tired the Pum-
per, and almo$t our own patience, we
<pb n=188>
gave over, the bubbles ri$e almo$t (if
not altogether) in as great numbers
as ever, in$omuch as none of the various
Liquors we tryed either before or $ince,
$eem'd to abound more with Aerial Parti-
cles then did this Oyl. In which it was
further remarkable, that between the time
it was $et into the Receiver, and that at
which we could get ready to Pump, it $ub-
$ided notably (by ghe$s about half an
Inch) below the mark it reach'd before it
was put in.
<p>After this expre$$'d Oyl, we made tryal
of a di$till'd one, and for that purpo$e
made choice of the common Oyl or Spi-
rit (for in the Shops where it is $old, the
$ame Liquor is promi$cuou$ly call'd by ei-
ther name) of Turpentine; becau$e 'twas
onely of that Chymical Oyl, we had a
$ufficient quantity: which, being put in-
to a $mall Gla$s bubble with a $lender
Neck, $o as to fill it to about two Inches
from the top, did, upon the evacuating
of the Receiver, pre$ent us with great
$tore of bubbles; mo$t of which ri$ing
from the bottom, expanded them$elves
exceedingly in their a$cent, and made the
Liquor in the Neck to $well $o much by
degrees, that at length it divers times ran
<pb n=189>
over at the top: by which means, we
were hindred from being able to di$cern
upon the letting in of the Air, how much
the $ub$idence of the Oyl below the fir$t
mark was due to the rece$s of the bub-
bles.
<p>Having likewi$e a minde to try whe-
ther as $trong a $olution of Salt of Tartar
in fair Water as could be made (we ha-
ving then no Oyl of Tartar <I>per deliqui-
um</I> at hand) though it be accounted,
Quick-$ilver excepted, the heavie$t of
Liquors would afford us any bubbles; we
put in a Gla$s Egge full of it at the $ame
time, with other Liquors, and found that
they did long yield $tore of bubbles be-
fore any di$covered them$elves in the
Liquor of Tartar; and having pur$ued
the Experiment, it appear'd, That of all
the Liquors we made tryal of, this afford-
ed the fewe$t and the $malle$t Bubbles.
<p>Spirit of Vinager being try'd after the
$ame manner, exhibited a moderate num-
ber of bubbles, but $carce any thing el$e
worth the mentioning.
<p>Nor could we in red Wine, try'd in a
Gla$s Egge, take notice of any thing ve-
ry ob$ervable. For though upon the ex-
$uction of the Air the bubbles a$cended
<pb n=190>
in this Liquor, as it were in $holes,
and $hifted places among them$elves in
their a$cent; yet the Intume$cence of the
whole bulk of the Liquor was $carce at all
$en$ible, the bubbles mo$t commonly
breaking very $oon after their arrival at
the top, where during their $tay, they
compo$'d a kinde of $hallow froth, which
alone appear'd higher in the Neck of the
Gla$s, then was the Wine when it was
fir$t let down. Neither yet did Milk, con-
vey'd into our Pneumatical Ve$$el, pre-
$ent us with any thing memorable, $ave
that (as it $eem'd by rea$on of $ome un-
ctuou$ne$s of the Liquor) the bubbles
not ea$ily breaking at the top, and thru$t-
ing up one another made the intume$cence
appear much greater then that of common
Water.
<p>We likewi$e convey'd Hens Eggs into
the Receiver, but, after the ex$uction of
the Air, took them out whole again. That
which invited us to put them in, was, That
(as perhaps we mention in other Papers)
we had among other Experiments of
cold, made Eggs bur$t, by freezing them
within doors with Snow and Salt: The
Ice, into which the aqueous parts of the
Egge were turned by the cold, $o di$tend-
<pb n=191>
ing (probably by rea$on of the numerous
bubbles wont to be ob$ervable in Ice) the
outward parts of the Egge, that it u$ually
crack'd the $hell, though the inner Mem-
brane that involv'd the $everal Liquors
of the Egge, becau$e it would $tretch
and yield, remain d unbroken, And here-
upon we imagin'd that in our Engine it
might appear whether or no there were
any con$iderable Spring, either in any of
the Liquors, or in any other more $piri-
tuous $ub$tance included in the Egge.
<p>We took al$o $ome Spirit of Urine,
carele$ly enough deflegmed, and put it in-
to the $ame Gla$s (fir$t carefully $cowr'd
and clean$'d) wherein we had put the Oyl-
olive above mention'd: We took al$o an-
other Gla$s, differing from a Gla$s Egge,
onely in that its bottom was $lat, and fill'd
it up to about 2/3 of the Neck (which was
wider then that of the Egge) with rectifi-
ed Spirit of Wine.
<p>We took al$o another Gla$s Egge, and
having fill'd it with common Water till it
reach'd to the middle of the Neck, we
pour'd to it of the $ame Spirit of Wine,
till it reach'd about an Inch higher.
<p>The$e three Gla$$es having marks $et
on them, over again$t the edges of the
<pb n=192>
contain'd Liquors were put into the Re-
ceiver, and that beginning to be evacua-
ted, the bubbles in all the three Liquors
began to appear. The mixture of the
Spirit of Wine and Water di$clo$'d a
great $tore of bubbles, e$pecially towards
the top; but $carce afforded us any thing
worth remem bring. The Spirit of Urine
appear'd to $well near an Inch and an half
above the mark; and be$ides that, $ent
forth $tore of bubbles, which made a
kinde of froth at the upper part of it. And
above that $pume there appear'd eight or
ten great bubbles one above another, in a
very decent order, each of them con$titu-
ting, as it were, a Cylinder of about half
an Inch high, and as broad as the internal
cavity of the Neck: So that all the upper
part of the Neck (for the$e bubbles reach'd
to the top) $eem'd to be divided into al-
mo$t equal parts, by certain Diaphrag-
mes, con$i$ting of the coats of the bub-
bles, who$e edges appear'd like $o many
Rings $u$pended one above another.
<p>In the Spirit of Wine there did ari$e a
great multitude of bubbles, even till
wearine$s did make us give over the Ex-
periment. And in the$e bubbles two or
three things were remarkable; as fir$t,
<pb n=193>
That they a$cended with a very notable
celerity: Next, That being arriv'd at the
top, they made no $tay there, and yet,
notwith$tanding the great thinne$s and
$pitituou$ne$s of the Liquor, did, before
they broke, lift up the upper $urface of
it, and for a moment or two form thereof
a thin film or skin which appear'd protu-
berant above the re$t of the $uperficies
like a $mall Hemi$phere. Thirdly, That
they a$cended $traight up, whereas tho$e
produc'd at the lower part of the Ve$$el,
containing the mixture of the Water and
Spirit of Wine, a$cended with a waver-
ing or wrigling motion, whereby they
de$crib'd an indented Line. La$tly, It
was ob$ervable in the Spirit of Wine (and
we took notice of the like in the Oyl of
Turpentine lately mention'd) that not
onely the bubbles $eem'd to ri$e from cer-
tain determinate places at the bottom of
the Gla$s, but that in their a$cen$ion they
kept an almo$t equal di$tance from each
other, and follow'd one another in a cer-
tain order, whereby they $eem'd part of
$mall Bracelets, con$i$ting of equally lit-
tle incontiguous Beads: the lower end of
each Bracelet, being as it were, fa$ten'd to
a certain point at the bottom of the Gla$s.
<pb n=194>
<p>The Air being $paringly let into the
Receiver, the great bubbles formerly
mention'd as incumbent upon one ano-
ther, in that Gla$s that contain'd the Spi-
rit of Urine, were by orderly degrees
le$$en'd, till at length they wholly $ub$i-
ded, notwith$tanding the rece$s of $o ma-
ny bubbles as broke on the top of the
Spirit of Urine, during all the time of the
Experiment; yet it $carcely appear'd at all
to be $unk below the mark: Nor did the
mixture of Spirit of Wine and Water
con$iderably $ub$ide. But that is no-
thing to what we ob$erv'd in the Spirit
of Wine, for not onely it con$picuou$ly
expanded it $elf in the Neck of the
Ve$$el that contain'd it, notwith$tand-
ing the largene$s of it; and that the
bubbles were about to break at the
top of it almo$t a$$oon as they arriv'd
there: but upon the re-admi$$ion of
the external Air, the Spirit of Wine
retain'd its newly acquired expan$ion.
And though we let it alone for near
an hour together, in expectation that it
might $ub$ide; yet when we took it
out, we found it $till $well'd between a
quarter and half an Inch above the
mark; and although it was not ea$ily
<pb n=195>
imaginable how this <I>Ph&aelig;nomenon</I> could
proceed from any mi$take in trying
the Experiment, yet the $trangene$$e
of it invited me to repeat it with fre$h
Spirit of Wine; which, $welling in the
Neck as formerly, I left all Night in
the Receiver, allowing free acce$s to the
external Air at the Stop-cock, and the
next day found it $till expanded as be-
fore, $ave that it $eem'd a little lower:
which decrement perhaps proceeded from
the avolation of $ome of the fugitive
parts of $o volatile a Liquor. And for
better $atisfaction having taken out the
Gla$s, and con$ider'd it in the open Air,
and at a Window, I could not finde that
there was any remaining Bubbles that
could occa$ion the per$evering and ad-
mir'd expan$ion.
<p>BEing de$irous to di$cover what diffe-
<MARG><I>Experi-
ment</I> 25.</MARG>
rence there might be as to gravity and
levity, between Air expanded under Wa-
ter, and it $elfe before $uch expan$ion; we
took two very $mall Viols, $uch as Chy-
mical E$$ences (as they call them) are wont
to be kept in, and of the $ize and $hape ex-
pre$$ed by the 8<SUP>th</SUP> Figure: into one of the$e
<pb n=196>
we put $o much of a certain ponderous
Mercurial mixture (hapning to be then at
hand) that the mouth being $topt with a
little $oft Wax, the Gla$s would ju$t $ink
in Water and no more; this we let fall to
the bottom of a wide-mouth'd Cry$tal
Jar, fill'd with about half a pint of com-
mon Water, and into the $ame Ve$$el we
$unk the other E$$ence Gla$s un$topp'd,
with as much Water in it as was more
then $ufficient to make it $ub$ide. Both
the$e $unk with their mouthes downward,
the former being about three quarters full
of Air, the latter containing in it a bub-
ble of Air that was ghe$$'d to be of the
bigne$s of half a Pea: This done, the
wide-mouth'd Gla$s was let down into
the Receiver, and the way of imploy-
ing the Engine was carefully made u$e
of.
<p>The $ucce$s was, That having drawn
out a pretty quantity of Air, the bubbles
began to di$clo$e them$elves in the Wa-
ter, as in the former Experiments; and
though for a good while after the bubbles
a$cended in $warms from the lower parts
of the Water, and ha$tily broke at the
top; yet we pro$ecuted the Experiment
$o long without $eeing any effect wrought
<pb n=197>
upon the E$$ence: Bottles, that we began
to di$pair of $eeing either of them ri$e, but
continuing to ply the Pump, that little
Gla$s, who$e mouth was open'd, came to
the top of the Water, being, as it were,
boy'd up thither by a great number of
bubbles that had fa$tned them$elves to
the $ides of it; $wimming thus with the
mouth downward, we could ea$ily per-
ceive that the internal Air above men-
tion'd had much delated it $elf, and there-
by $eem'd to have contributed to the e-
merging of the Gla$s, which remain'd
floating, notwith$tanding the breaking
and vani$hing of mo$t of the contiguous
bubbles: being hereby incouraged to per-
$i$t in pumping, we ob$erved with $ome
plea$ure, that at each time we turn'd the
Key, the Air in the little Gla$s did mani-
fe$tly expand it $elf and thru$t out the wa-
ter, generally retaining a very protuberant
$urface where it was contiguous to the re-
maining Water. And when after divers
ex$uctions of the Air in the Receiver,
that in the little Viol $o dilated it $elf as
to expel almo$t all the Water, it turn'd
up its mouth towards the $urface of the
Water in the Jar, and there deliver'd a
large bubble, and then relap$ed into its
<pb n=198>
form&eacute;r floating po$ture: And this Expe-
riment taught us, among other things,
that it was a work of more time and la-
bor then we imagin'd, to exhau$t our En-
gine as much as it may be exhau$ted: for
although before the emerging of the $mall
Viol, we did (as has been touch'd alrea-
dy) think we had very con$iderably em-
ptyed the Receiver, becau$e there $eem'd
to come out but very little or almo$t
no $en$ible Air at each ex$uction into
and out of the Cylinder; yet after-
wards, at each drawing down the Suc-
ker, the Air included in the Viol did
manife$tly dilate it $elf, $o long, that
it did no le$s then nine times turn its
mouth upwards, and di$charge a bub-
ble by conjecture about the bigne$s of
a Pea, after the manner newly recited.
But as for that Violl which had the
weight in it, it ro$e not at all. So
that being not able by quick pumping
to gain another bubble from the Air
in the $wimming Gla$s, which proceed-
ed from $ome $mall leak in the Ve$$el,
though it held in this Experiment more
$tanch then was u$ual, we thought fit
to let in lea$urely the Air from with-
out, upon who$e admi$$ion that with-
<pb n=199>
in the Viol $hrinking into a very nar-
row compa$s, the Gla$s did, as we expe-
cted, fall down to the bottom of the
Jar.
<p>But being de$irous before we proceed-
ed to any new. Experiment, to try once
more whether the little Gla$s that had
the weight in it might not al$o be rai$'d.
After we had $uffer'd the Engine to re-
main clo$'d as it was, for five or $ix
hours, the Pump was again ply'd with
$o much ob$tinacy, that not onely a-
bout the upper part of the Jar there ap-
pear'd a good number of bubbles (but
very much $maller then tho$e we $aw
the fir$t time) but afterwards there
came from the bottom of the Jar, bub-
bles about the bigne$s of $mal Peas: which
the Pump being $till kept going, fol-
low'd one another, to the number of forty,
coming from the $topp'd Violl; who$e
mouth, it $eems, had not been $hut $o
$trongly and clo$ely, but that the included
Air, dilating it $elf by its own $pring, made
it$elf $ome little pa$$age betwixt the Wall
and the Gla$s, and got away in the$e bub-
bles; after which, the un$topp'd Gla$s be-
gan to float again, the Air $hut up in it
<pb n=200>
being manife$tly $o dilated as to expel a
good part of the Water, but not $o much
as to break quite thorow. And at length,
when our expectation of it was almo$t ti-
red out, the heavier of the two Viols be-
gan to come aloft, and immediately to
$ub$ide again, which appear'd to be oc-
ca$ion'd by the Air within it, who$e bulk
and $pring being weaken'd by the rece$s
of the forty bubbles before-mention'd, it
was no longer able, as formerly, to break
forcibly through the incumbent Water;
but forming a bubble at the mouth of the
Gla$s, boyed it up towards the top, and
there getting away, left it to $ink again
till the pre$$ure of the Air in the Recei-
ver being further taken off, the Air in the
Viol was permitted to expand it $elf fur-
ther, and to create another bubble, by
which it was again for a while carried up.
And it was remarkable, that though after
having emptyed the Receiver as far as
well we could, we cea$'d from pumping;
yet the Ve$$el continuing more $tanch
then it was wont, this a$cent and fall of
the Viol was repeated to the ninth time;
the included Air, by rea$on of the $mal-
ne$s of the vent at which it mu$t pa$s out,
being not able to get away otherwi$e then
<pb n=201>
little by little; and con$equently, in divers
$uch parcels as were able to con$titute
bubbles, each of them big enough to
rai$e the Viol and keep it aloft until the
avolation of that bubble. Whereby it
may appear, that the grand rule in <I>Hy-
dro$taticks,</I> That a Body will $wim in the
Water, in ca$e it be lighter then as much
of that Water that equals it in bulk, will
hold likewi$e when the pre$$ure of the At-
mo$phere is in very great mea$ure, if not
when it is totally taken off from the Li-
quor and the Body: though it were worth
inquiring what it is that $o plentifully
concurs to fill the bubbles made in our
Experiment by the $o much expanded
Air, for to $ay with the old Peripatetick
Schools, That the Air, in Rarefaction,
may acquire a new extent, without the
admi$$ion of any new $ub$tance, would
be an account of the <I>Ph&aelig;nomenon</I> very
much out of date, and which, I $uppo$e,
our Modern Naturali$ts would neither
give, nor acquie$s in.
<p>I know not whether it may be requi$ite
to adde, that in this Experiment, as in
the former, the outward Air being let in
did $oon precipitate the floating Viol. But
I think it will not be ami$s to note, that
<pb n=202>
(congruou$ly to what hath been above
recorded of the va$t expan$ion of the Air)
the Water which in the heavier Viol $uc-
ceeded in the room of tho$e forty odde, if
not fifty great bubbles of Air, which at
$everal times got out of it, amounted but
to a very incon$iderable bigne$s.
<p>IT having been ob$erv'd by tho$e that
<MARG><I>Experi-
ment</I> 26.</MARG>
have con$ider'd what belongs to <I>Pendu-
lums</I> (a Speculation that may, in my
poor judgement, be highly u$eful to the
Naturali$ts) that their Vibrations are
more $lowly made, and that their moti-
on la$ts le$s in a thicker, then in a thinner
Medium: We thought it not ami$s to
try if a <I>Pendulum</I> would $wing fa$ter, or
continue $winging longer in our Receiver,
in ca$e of the ex$uction of the Air, then
otherwi$e. Wherefore we took a couple
of round and poli$h'd <I>Pendulums</I> of Iron
or Steel, of equal bigne$s, as near as we
could get the Artificer to make them, and
weighing each of them twenty Dragmes,
wanting as many Grains. One of the$e
we $u$pended in the cavity of the Recei-
ver by a very $lender $ilken $tring, of a-
bout $even Inches and a half in length
<pb n=203>
from the cover of the Receiver to which
it was fa$ten'd. Then (by inclining the
Engine) we made the <I>Pendulum</I> $wing too
and fro in it, and de$crib'd as long Arches
as in the capacity of $o brittle a Ve$$el we
thought $afe and convenient. And one of
the A$$i$tants telling the recur$ions of the
other <I>Pendulum</I> hanging in the free Air,
by a $tring of about the $ame length, we
$horten'd and lengthen'd this other <I>Pen-
dulum,</I> till it appear'd to keep the $ame
pace in its Vibrations, with that $hut up in
the Receiver. Then having carefully
drawn away the Air, we did again $et the
<I>Pendulum</I> in the Receiver a vibrating;
and giving the other <I>Pendulum</I> $uch a mo-
tion as made it de$cribe an Arch, accord-
ing to ones ghe$s, equal to that of the in-
cluded <I>Pendulum;</I> we reckon'd, one of
us, the Recur$ions of that <I>Pendulum</I> which
was $winging within the Receiver; and
another of us that which was moving in
(that which one would think a much more
re$i$ting <I>medinm</I>) the Air. But once, one
of us reckon'd near two and twenty Re-
cur$ions of the included <I>Pendulum,</I> whil$t
the other reckon'd but twenty of the <I>Pen-
dulum</I> that vibrated without. And an-
other time al$o, the former of the$e <I>Pen-</I>
<pb n=204>
<I>dula</I> was reckon'd to have made one and
twenty Recur$ions, wherein the other
made but twenty: Yet this Experiment
$eem'd to teach us little, $ave that the dif-
ference betwixt the motion of $uch a <I>Pen-
dulum</I> in the common Air, and in one ex-
ceedingly rarified, is $carce $en$ible in
Ve$$els no bigger then our Receiver; e-
$pecially $ince though during this Expe-
riment it held very well, yet we could
not $uppo$e it to be altogether devoid of
Air. We ob$erv'd al$o, that when the
Receiver was full of Air, the included
<I>Pendulum</I> continu'd its Recur$ions about
fifteen minutes (or a quarter of an hour)
before it left off $winging; and that after
the ex$uction of the Air, the Vibration
of the $ame <I>Pendulum</I> (being fre$h put in-
to motion) appear'd not (by a minutes
Watch) to la$t $en$ibly longer. So that
the event of this Experiment being other
then we expected, $carce afforded us any
other $atisfaction, then that of our not
having omitted to try it. And whether
in ca$e the tryal be made with a <I>Pendulum</I>
much le$s di$proportionate to the Air then
Steel is, the event will much better an-
$wer expectation, experience may be con-
$ulted.
<pb n=205>
<p>THat the Air is the medium whereby
$ounds are convey'd to the Ear, has
<MARG><I>Experi-
ment</I> 27.</MARG>
been for many Ages, and is yet the com-
mon Doctrine of the Schools. But this
Received Opinion has been of late op-
po$'d by $ome Philo$ophers upon the ac-
count of an Experiment made by the
Indu$trious <I>Kircher,</I> and other Learned
Men, who have (as they a$$ure us) ob-
$erv'd, That if a Bell, with a Steel Clap-
per, be $o fa$ten'd to the in$ide of a Tube,
that upon the making the Experiment <I>De
Vacuo</I> with that Tube, the Bell remain'd
$u$pended in the de$erted $pace at the up-
per end of the Tube: And if al$o a vi-
gorous Load-$tone be apply'd on the out-
$ide of the Tube to the Bell, it will at-
tract the Clapper, which upon the Remo-
val of the Load-$tone falling back, will
$trike again$t the oppo$ite $ide of the
Bell, and thereby produce a very audible
$ound, whence divers have concluded,
That 'tis not the Air, but $ome more $ub-
tle Body that is the medium of $ounds.
But becau$e we conceiv'd that, to invali-
date $uch a con$equence from this ingeni-
ous Experiment (though the mo$t lucife-
<pb n=206>
rous, that could well be made without
$ome $uch Engine as ours) $ome things
might be $peciou$ly enough alleadg'd; we
thought fit to make a tryal or two, in or-
der to the Di$covery of what the Air does
in conveying of $ounds, re$erving divers
other Experiments tryable in our Engine
concerning $ounds, till we can obtain more
lea$ure to pro$ecute them. Conceiving it
then the be$t way to make our tryal with
$uch a noi$e as might not be loud enough
to make it difficult to di$cern $lighter va-
riations in it, but rather might be, both
la$ting, that we might take notice by what
degrees it decrea$'d; and $o $mall, that
it could not grow much weaker with-
out becoming imperceptible. We took
a Watch, who$e Ca$e we open'd, that
the contain'd Air might have free egre$s
into that of the Receiver. And this Watch
was $u$pended in the cavity of the Ve$$el
onely by a Pack-thred, as the unlikelie$t
thing to convey a $ound to the top of the
Receiver: And then clo$ing up the Ve$-
$el with melted Plai$ter, we li$ten'd near
the $ides of it, and plainly enough heard
the noi$e made by the ballance. Tho$e al-
$o of us, that watch'd for that Circum-
$tance, ob$erv'd, that the noi$e $eem'd to
<pb n=207>
come directly in a $traight Line from the
Watch unto the Ear. And it was ob$erva-
ble to this purpo$e, that we found a mani-
fe$t di$parity of noi$e, by holding our Ears
near the $ides of the Receiver, and near the
Cover of it: which difference $eem'd to
proceed from that of the Texture of the
Gla$s, from the $tructure of the cover (and
of the Cement) through which the $ound
was propagated from the Watch to the
Ear. But let us pro$ecute our Experiment.
The Pump after this being imployd, it
$eemd that from time to time the $ound
grew fainter and fainter; $o that when the
Rec iver was empty'd as much as it u$'d
to be for the foregoing Experiments, nei-
ther we, nor $ome $trangers that chanc'd
to be then in the room, could, by applying
our Ears to the very $ides, hear any noi$e
from within; though we could ea$ily per-
ceive that by the moving of the hand
which mark'd the $econd minutes, and by
that of the ballance, that the Watch nei-
ther $tood $til, nor remarkably varied from
its wonted motion. And to $atisfie our
$elvs further that it was indeed the ab$ence
of the Air about the Watch that hinder'd
us from hearing it, we let in the external
Air at the Stop-cock, and then though we
<pb n=208>
turn'd the Key and $topt the Valve, yet we
could plainly hear the noi$e made by the
ballance, though we held our Ears $ome-
times at two Foot di$tance from the out-
$ide of the Receiver. And this Experi-
ment being reiterated in another place,
$ucceded after the like manner. Which
$eems to prove, that whether or no the
Air be the onely, it is at lea$t, the princi-
pal medium of Sounds. And by the way
it is very well worth noting, that in a Ve$-
$el $o well clo$'d as our Receiver, $o weak
a pul$e as that of the ballance of a Watch
$hould propagate a motion to the Ear in a
Phi$ically $traight Line, notwith$tanding
the interpo$ition of $o clo$e a Body as
Gla$s, e$pecially Gla$s of $uch thickne$s
as that of our Receiver; $ince by this it
$eems that the air impri$on'd in the Gla$s,
mu$t, by the motion of the ballance, be
made to beat again$t the concave part of
the Receiver, $trongly enough to make
its convex part beat upon the contiguous
Air, and $o propagate the motion to the
Li$tners ears. I know this cannot but
$eem $trange to tho$e, who, with an emi-
nent Modern Philo$opher, will not allow
that a Sound, made in the cavity of a
Room, or other place $o clo$'d, that there
<pb n=209>
is no intercour$e betwixt the external and
internal Air, can be heard by tho$e with-
out, unle$s the $ounding Body do imme-
diately $trike again$t $ome part of the in-
clo$ing Body. But not having now time
to handle Controver$ies, we $hall onely
annex, That after the foregoing Experi-
ment, we took a Bell of about two Inches
in Diameter at the bottom, which was
$upported in the mid$t of the cavity of
the Receiver by a bent $tick, which by
rea$on of its Spring pre$$'d with its two
ends again$t the oppo$ite parts of the in-
$ide of the Ve$$el: in which, when it was
clo$'d up, we ob$erv'd that the Bell $eem'd
to $ound more dead then it did when ju$t
before it $ounded in the open Air. And
yet, when afterwards we had as formerly
emptyed the Receiver, we could not di$-
cern any con$iderable change (for $ome
$aid they ob$erv'd a $mall one) in the loud-
ne$s of the $ound, whereby it $eem'd that
though the Air be the principal medium
of $ound, yet either a more $ubtle mat-
ter may be al$o a medium of it, or el$e an
ambient Body that contains but very
few particles of Air, in compari$on of
tho$e it is ea$ily capable of, is $ufficient
for that purpo$e. And this, among o-
<pb n=210>
ther things, invited us to con$ider, whether
in the above-mention'd Experiment made
with the Bell and the Load-$tone, there
might not in the de$erted part of the Tube
remain Air enough to produce a $ound:
$ince the Tubes for the Experiment <I>De
Vacuo</I> (not to mention the u$ual thin-
ne$s of the Gla$s) being $eldom made
greater then is requi$ite, a little Air might
bear a not incon$iderable proportion to
the de$erted $pace. And that al$o, in the
Experiment <I>De Vacuo,</I> as it is wont to be
made, there is generally $ome little Air
that gets in from without, or at lea$t $tore
of bubbles that ari$e from the Body of
the Quick-$ilver, or other Liquor it $elf,
Ob$ervations heedfully made have fre-
quently informed us: And it may al$o
appear, by what has been formerly deli-
vered concerning the <I>Torricellian</I> Experi-
ment.
<p>On the occa$ion of this Experiment
concerning $ounds, we may adde in this
place, That when we try'd the Experiment
formerly mention'd, of firing Gun-pow-
der with a Pi$tol in our evacuated Recei-
ver, the noi$e made by the $triking of the
Flint again$t the Steel, was exceeding
languid in compari$on of what it would
<pb n=211>
have been in the open Air. And on di-
vers other occa$ions it appear'd that the
$ounds created within our exhau$ted
Gla$s, if they were not lo$t before they
reach'd the Ear, $eem'd at lea$t to arrive
there very much weaken'd. We intended
to try whether or no the Wire-$tring of an
In$trument $hut up into our Receiver,
would, when the ambient Air was $uck'd
out, at all tremble, if in another In$trument
held clo$e to it, but without the Receiver
a $tring tun'd (as Mu$icians $peak, how
properly I now examine not) to an Uni$on
with it, were briskly toucht, and $et a Vi-
brating. This, I $ay, we purpo$'d to try
to $ee how the motion made in the Air
without, would be propagated through the
cavity of our evacuated Receiver. But
when the In$trument wherewith the tryal
was to be made came to be imploy'd, it
prov'd too big to go into the Pneumatical
Ve$$el, and we have not now the conveni-
ency to have a fitter made.
<p>We thought likewi$e to convey into
the Receiver a long and $lender pair of
Bellows, made after the fa$hion of tho$e
u$ually employ'd to blow Organs, and fur-
ni$h'd with a $mall Mu$ical in$tead of an
<pb n=212>
ordinary Pipe. For we hop'd, that by
means of a $tring fa$tned to the upper
part of the Bellows, and to the moveable
$topple that makes a part of the Cover
of our Receiver, we $hould, by frequent-
ly turning round that $topple, and the an-
nexed $tring, after the manner already
often recited, be able to lift up and di$tend
the Bellows; and by the help of a com-
petent weight fa$ten'd to the $ame upper
part of the Bellows, we $hould likewi$e
be able, at plea$ure, to compre$s them:
and by con$equence, try whether that
$ubtler matter then Air (which, accord-
ing to tho$e that deny a <I>Vacuum,</I> mu$t be
$uppo$'d to fill the exhau$ted Receiver)
would be able to produce a $ound in the
Mu$ical Pipe; or in a Pipe like that of or-
dinary Bellows, to beget a Wind capable
to turn or $et a moving $ome very light
matter, either $hap'd like the Sails of a
Wind-Mill, or of $ome other conveni-
ent form, and expo$'d to its Orifice. This
Experiment, I $ay, we thought to make,
but have not yet actually made it for want
of an Artificer to make us $uch a pair of
Bellows as it requires.
<p>We had thoughts al$o of trying whe-
ther or no, as Sounds made by Bodies in
<pb n=213>
our Receiver become much more languid
then ordinary, by rea$on of the want of
Air, $o they would grow $tronger, in ca$e
there were an unu$ual quantity of Air
crouded and $hut up in the $ame Ve$$el,
which may be done (though not without
$ome difficulty) by the help of the Pump,
provided the Cover and Stopple be $o
firmly fa$ten'd (by binding and Cement,
or otherwi$e) to the Gla$s; and to each
other, that there be no danger of the
conden$'d Airs blowing of either of them
away, or its breaking through the jun-
ctures. The$e thoughts, My Lord, as I
was $aying, we entertain'd; but for want
of lea$ure, as, of as good Receivers as
ours, to $ub$titute in its place, in ca$e we
$hould break it before we learn'd the skill
of condencing the Air in it, we dur$t not
put them in practice: Yet, on this occa-
$ion, give me leave to adverti$e Your
Lord$hip once for all, That though for
the rea$ons newly intimated, we have,
Onely in the $eventeenth Experiment,
taken notice, that by the help of our En-
gine the Air may be conden$'d as well as
rarified; yet there are divers other of our
Experiments, who$e <I>Ph&aelig;nomena</I> it were
<pb n=214>
worth while to try to vary, by means of
the compre$$ion of the Air.
<p>WE taught, among divers other
<MARG><I>Experi-
ment</I> 28.</MARG>
things, when we di$cour$'d of our
fir$t Experiment, That the Air $hut up in
our Receiver, pre$$eth as $trongly upon
the Bodies $hut up with it, as if they
were expo$'d to the pre$$ure of the whole
Atmo$phere. That this was not incon-
$iderately propounded, we hope Your
Lord$hip has gather'd from divers of the
things already recited: But yet perhaps it
will not be ami$s to $ubjoyn, by way of
further confirmation of the $ame truth, the
following Experiment, which $hould have
accompanied the 20<SUP>th</SUP>, but the Paper where
in the one was written chanc'd not to beat
hand, when the other was $ent away.
<p>We convey'd into the Receiver a new
Gla$s Viol, capable of holding about 6 or
7 ounces of Water, into which we had
before put 2 or 3 Spoon-fulls of that Li-
quor, and $topt it clo$e with a fit Cork.
The Pneumatical Ve$$el being empty'd,
there appear'd not any change in the in-
clo$'d Water, the Air impri$on'd with it,
not having the force to blow out the $top-
<pb n=215>
ple, which event, though it were no other
then we expected, was differing from what
we de$ir'd. For we would gladly have $een
what change would have appear'd in the
Water upon the Bottles being $uddenly
un$topp'd, in a place where the ambient
Body was $o differing from our common
Air. Wherefore we did again put in the
Viol, but le$s $trongly clo$'d then for-
merly, though as $trongly $topt as $eem'd
requi$ite on ordinary occa$ions: But when
the Air was pump'd out of the Receiver,
that within the Viol did quickly, as we
expected, find or make it $elf little pa$$a-
ges to get out at: as we argu'd, from this,
That whereas when the Viol was put in
the time before, the Water remain'd all
the while perfectly free from bubbles; at
this time the bottom of the Gla$s ap-
pear'd all cover'd with them, and they,
upon the regre$s of the excluded Air into
the Receiver, did pre$ently flag and $hrink
up.
<p>From the$e tryals it $eem'd deducible
enough, that whil'$t the Viol continu'd
to be well $topt, the included Water
did, from the Air, $hut up with it,
$u$tain a pre$$ure equal to that of the
Atmo$phere; $ince till the Air could get
<pb n=216>
out of the Gla$s, there appear'd no bub-
bles in the Water, notwith$tanding the
want of pre$$ure in the ambient Body.
<p>But to be $ure to reach the chief end of
our Experiment, we made u$e of this o-
ther expedient: We cau$'d a convenient
quantity of Water to be put, and Her-
metically $hut up into a Gla$s Egge, to
who$e long Neck (which was purpo$ely
made of an unequal thickne$s) was fa-
$ten'd to one end of a $tring, who$e o-
ther end was ty'd to the Cover of our
Receiver, after the manner el$ewhere men-
tion'd already: Then the Egge being
convey'd into the Pneumatical Ve$$el,
and that being evacuated, we did, by
turning the bra$s Stopple formerly de-
$crib'd among$t the parts of our En-
gine, $o $horten the $tring as to break the
Gla$s; whereby liberty being given to
the Air impri$on'd in the Egge, to pa$s
into the capacity of the Receiver, the $ud-
den rece$s of the Air made the bubbles in
a trice appear $o numerous, and a$cend
$o $wiftly in the Water, that their motion
look'd like that of a violent $hower of
Rain; $ave that the bubbles did not, like
the drops of Rain, tend downwards, but
upwards, which made me re$emble this
<pb n=217>
<I>Ph&aelig;nomenon</I> to what I have $een happen
in the di$$olution of Seed-Pearl in $ome
acid <I>Men$truum,</I> in which, if a good quan-
tity of the little Pearls be ca$t whole, they
will at fir$t, if the <I>Men$truum</I> be $harp e-
nough, be carryed in $warms from the
bottom to the top of the Liquor. We
will adde, that without $ealing up the
Gla$s, this Experiment may be try'd in
one of our $malle$t Receivers, for there
the ex$uction of the ambient Air may be
perform'd $o nimbly, that immediately
the bubbles lurking in the Water are al-
low'd to di$play them$elves, and a$cend
in throngs; in$omuch, as having in $uch
a Receiver try'd the Experiment with
Wine (as a more $pirituous Liquor) in-
$tead of Water, the Red-Wine appear'd
all cover'd, with a copious, but vani$hing
white Froth, almo$t as if a Ve$$el full of
bottl'd drink had been unwarily open'd.
<p>IT may not a little conduce to the clear-
<MARG><I>Experi-
ment</I> 29</MARG>
er explication of divers Points in the
Doctrine of Meteors, and perhaps of
$ome other Phy$iological difficulties, to
di$cover what the Air does to the motion
of tho$e Steams or Exhalations that a$-
<pb n=218>
cend into it, namely, Whether they mount
upwards by vertue of any $uch <I>po$itive le-
vity</I> (as $ome Peripateticks $peak) ac-
quir'd together with their A&euml;rial nature,
as inables them to pierce through part of
the Atmo$phere, and over-come its re-
$i$tance. Or el$e, whether the$e $teams
being once rai$'d above the Earth by their
agitation, have their a$cent and $u$tenta-
tion aloft, rather promoted then hindred
by the Air: as the inferior parts of that,
being thicker and heavier then the $upe-
rior, the $teams can more ea$ily continue
for a while their agitation upwards then
downwards; And afterwards are by the
$ame fluidity and thickne$s of the Air,
carried to and fro in it, and kept from re-
lap$ing to the Earth, as in the Sea water
the $aline parts are kept from $ub$iding by
tho$e aqueous ones wherewith they are
a$$ociated.
<p>We hop'd to illu$trate this matter, by
ob$erving the motion of the $moke, pro-
ceeding from kindled or flaming Bodies in
our exhau$ted Receiver. But as we for-
merly noted, upon the ex$uction of the
Air, the $moking of tho$e Bodies pre-
$ently cea$'d. We had thoughts al$o of
conveying into our Pneumatical Gla$s a
<pb n=219>
hot Iron, with $ome Body ea$ie to be
di$$ipated into $moke $et upon it, but con-
$ider'd, that neither was that way free
from inconveniencies; e$pecially this, that
the hot Body would make the Impri$on'd
Air circulate within the Receiver, and
con$equently make it que$tionable whe-
ther the a$cent of the $teams would not
be due to the new and acquired motion of
the Air.
<p>Wherefore I bethought my $elf of an-
other way to $atisfie in $ome mea$ure my
curio$ity, to wit, by means of a certain
Liquor, which I call'd to minde that $ome
years ago I had (for a de$ign that belongs
not to our pre$ent purpo$e) prepar'd;
which, I $uppo$e, I $hew'd Your Lord-
$hip, and which had the luck to be ta-
ken notice of by divers very Ingenious
and Famous Men. For this Liquor,
though mo$t of its Ingredients be Metals,
and all of them ponderous enough, is yet
of that nature, that whil$t the Viol where-
in it is kept is $topt (how $light a Cover
$oever) both the Liquor and the Gla$s
are tran$parent; and $o is that upper half
of the Gla$s to which the Liquor reaches
not. But a$$oon as ever the $topple is ta-
ken out, and full acce$s is given to the ex-
<pb n=220>
ternal Air, both the inward part of the
Cork, and the Liquor it $elf, do pre$ent-
ly $end upwards, and $catter abroad a
fume as thick and white, as if there were
a quantity of Alabla$ter-du$t thrown up
into the Air: And this $moking of the
Liquor la$ts till my unwillingne$s to wa$te
it, invites me $top it again; and then the
a$cen$ion of the fumes $uddenly cea$es, till
the Viol be again un$top'd.
<p>This fuming Liquor then I thought
would much conduce to the di$covery I
de$ir'd to make, $ince it $av'd me the need
of conveying any hot Body with it into
the Receiver, and would not darken it
with fumes before the time. Wherefore
having ty'd to the Viol a great weight of
Lead, to keep it from being lifted up by
the drawing out of the Cork; and having
ty'd to the $topple one end of a $tring, of
which the other end was made fa$t to the
Cover of the Pneumatical Gla$s, the Li-
quor was carefully clo$'d up after the
wonted manner; then the Air being dili-
gently pump'd out, the Viol was un$topt
in the empty'd Receiver: and though
immediately, npon the drawing out of the
Cork, there appear'd to be as it were
thrown up $ome white fumes, which
<pb n=221>
$eem'd to proceed from the Air before
impri$on'd in the Viol, and diffu$ing it
$elf $uddenly into the capicity of the
Receiver. Yet we afterward ob$erv'd,
as we expected, That the fumes did not
mount and di$per$e them$elves as they
u$e to do in the open Air, but that, when
by rea$on of the agitation of the Cor-
pu$cles of the Liquor, which could not
continue their motion in $o narrow a
$pace as the Viol afforded them, and were
therefore reduc'd to thru$t one another
out of it; when, I $ay, by the$e a$$i-
$tances the fumes were a$cended to the lip
of the Viol, they mounted no higher,
but ran down along the out-$ide of the
Viol to the bottom of it; and thence
along, a long and inclining piece of Lead,
on which the Viol re$ted, like a little
Stream (not very much bigger then a
Swans Quill) who$e nature it $eemd to e-
mulate $o well, that it quitted not the Viol
till it was come to the bottom of it, and
then for$ook it in $uch a manner as a
$tream of Water of the $ame bigne$s
would have done. And this $tream la$ted
a pretty while, and would probably have
la$ted longer, but that being loath to wa$te
my Liquor, I let in at the Stop-cock a
<pb n=222>
pretty deal of the external Air; notwith-
$tanding which, finding after a while the
$tream did run afre$h; though, as it $eem'd,
not altogether $o copious as before: I let
as much more Air, as would, come in, and
found ($omewhat to my wonder) that
though the $tream formerly mention'd
di$-appear'd, yet there appear'd not any
white fumes to ari$e, either from the Cork,
or out of the Viol it $elf, no not when
the Cover was remov'd from the Recei-
ver; though not onely after a while there
a$cended white Fumes from the Receiver:
but having forthwith taken out the Viol
into the open Air, it emitted white ex-
halations as before; and having pre$ently
after un$top'd it in an open Window, we
found both it and the Cork immediatly
to $end forth a yet much more plentiful
$moak. Though it be now divers years
$ince this Numerical Liquor was prepa-
red, after the manner mention'd either
by <I>Carneiades</I> or <I>Eleutherius</I> (for I do not
well remember which) in tho$e Dialogues
concerning Heat and Flame that have a-
bove been mention'd.
<p>More Circum$tances concerning the$e
Fumes we might have ob$erv'd, had we
not been deterr'd by an Indi$po$ition in
<pb n=223>
point of health, from having much to do
with $teams of $o dangerous a nature, as by
that of the Ingredients of this Liquor
the$e $eem likely to be of.
<p>The Reflections that may be made up-
on this Experiment, we have not now the
lea$ure to pro$ecute, and therefore $hall
content our $elves to recommend the $e-
veral Circum$tances of it to Your Lord-
$hips $erious con$ideration; and to take
notice <I>(en pa$$ant)</I> that $teams in an am-
bient Body, or a medium thinner then
them$elves, may both tend downwards,
and otherwi$e emulate the nature of a
Liquor; which I therefore point at, that
it may appear the le$s $trange, if we $ome-
times $peak of the Atmo$phere as of a
kinde of Liquor, in compari$on of that
more thin and $ubtle Cele$tial Matter that
$urrounds it.
<p>And though it might perchance $uf-
fice to have on this occa$ion intima-
ted thus much; yet, le$t this way
of $peaking of the Atmo$phere $hould
be thought too bold and extra-
vagant, I am content to borrow an
Experiment of the Di$cour$e former-
<pb n=224>
ly mention'd (touching fluidity and firm-
ne$s) and $ubjoyn it here with alterations
$uitable to the contrivance of our Engine;
and this the rather, becau$e I hope it may
conduce to the di$covery of the nature of
the Atmo$phere: for which rea$on it
might have been annext to what has been
noted either upon the fir$t, or eighteenth
Experiment, but that when they were
written and $ent away, it came not into
my minde. The Experiment then as we
try'd in our Engine, was as follows.
<p>WE took one of the $mall Receivers,
<MARG><I>Experi-
ment</I> 30.</MARG>
often mention'd already, and into it
we convey'd a piece of well lighted Match;
and letting it remain there till it had fill'd
the Receiver with $moak, we took it out
and ha$tily clo$'d again the Receiver, that
the $moak might not get away. Then
$taying awhile to let the$e fumes lei$urely
$ub$ide, we found, as we expected, that
after $ome time they $etled them$elves in
the lower half of the Receiver, in a dark-
i$h Body, leaving the upper half of the
Receiver tran$parent, and as to $ight, full
of nought but clear Air. Now to mani-
fe$t that this $moak thus $etled emulated
<pb n=225>
a Liquor, we inclin'd the Engine that con-
tain'd it, $ometimes to one $ide, and $ome-
times to the other; and ob$erv'd the
$moak to keep its $urface almo$t Hori-
zontal, notwith$tanding the $tooping of
the Ve$$el that held it, as Water or an-
other Liquor would in the like ca$e have
done. And if by a quicker rocking of the
Engine the $moke were more $wiftly $ha-
ken, it would, like Water, either Vibrate
to and fro from one $ide to the other of
the Gla$s, or el$e have its $urface manife$t-
ly curll'd with Waves, but pre$erve its
$elf in an intire and di$tinct Body from the
incumbent Air; and being permitted to
re$t awhile, would $oon recover its for-
mer $mooth and level <I>$uperficies:</I> If al$o
the Key were turn'd and the Valve un-
$topp'd, $o that there was a free, though
but a narrow pa$$age open'd betwixt the
external Air and the cavity of the Recei-
ver, then would $ome of this $moak fall
down, as it were, in a $tream into the $ub-
jacent Cylinder, and a proportionate
quantity of the outward Air, would ma-
nife$tly a$cend through it into the incum-
bent Air, much after the $ame manner as
if you invert a Viol with a long Neck, and
well fill'd with Red-Wine, into a Gla$s
<pb n=226>
full of fair water, you $hall $ee the Water
and Wine by degrees mingle with one an-
other; the one falling downe as it were in
little colour'd $treames, and the other a$-
cending into its room in the like curled
$treames, $ometimes preceded by round
parcels of water, which, by rea$on of their
tran$parency, looke almo$t like bubbles.
The other circum$tances of this Experi-
ment, belonging not all of them to our
pre$ent purpo$e, we $hall content our
$elves with taking notice of one which
$eemes the mo$t important, and may illu-
$trate and confirme $ome things former-
ly delivered. And it was, That if, when
the <I>$uperficies</I> of our Smoke lay $mooth
and horizontal, a hot iron were held near
the our $ide of the Receiver, the Neigh-
bouring part of the included fumes (for
the re$t did not very much alter their for-
mer <I>$uperficies</I>) being rarified by the heat,
would readily a$cend in a large Pillar of
$moke to the very top of the Receiver,
yet without $eeming to loo$e a di$tinct
<I>$uperficies,</I> or to be confounded with Air;
below which, upon the rece$s of the ad-
ventitious heat that by agitating it im-
pell'd it upward, it would againe $ub-
$ide.
<pb n=227>
<p>All which being added to the late Ex-
periment of the $moking Liquor, and
to what may be from that which has been
el$ewhere $ayd, gather'd to the $ame pur-
po$e, will, I hope, keep it at lea$t from ap-
pearing ab$ur'd: If $ince we $ee that there
is $o great an inequality in the den$ity and
weight of Liquors, that water is neere 14
times thinner or lighter than Quick-$ilver
of the $ame bulk, and well dephlegm'd;
Spirit of Wine yet much lighter than wa-
ter; we venter to $peak $ometimes of the
Atmo$phere, as if it were a peculiar kind
of thin and halituous Liquor (if I may $o
call it) much lighter than Spirit of Wine.
<p>To the$e things I know not whether it
will be requi$ite to add, that as we late-
ly took notice of con$picuous waves that
appear'd upon the <I>$uperficies</I> of our agi-
tated $moke. So $ome $uch thing may
not ab$urdly be conjectur'd to happen
on the <I>$uperficies</I> of the Atmo$phere,
by tho$e $trange ruggedne$$es that ap-
peare (e$pecially in the Spring and Fall,
when exhalations and vapours are wont to
a$cend mo$t plentifully) upon the Limb
or Edge of the Ri$ing and Setting Sun. I
$peake thus diffidently upon this occa$ion
becau$e I know that by the Fluctuation or
<pb n=228>
Boyling of the Sun's own <I>$uperficies</I> di-
ver$e eminent Mathematicians have plau-
$ibly enough (but how truly I leave
your Lord$hip to Judge) endeavour'd to
give an Account of it. But if we will joine
with tho$e that have a$crib'd of late this
<I>Ph&aelig;nomenon</I> to the Refraction the Sun-
Beames fuffer in our vapid Air; we may,
as hath been intimated, promote their Do-
ctrin by deducing from it, that probably
the $urface Atmo$phere is oftentimes (if
not alwayes) exceedingly curl'd or wav'd.
And certainly it is $omewhat wonderfull
as well as very plea$ant to behold, how,
to him that looks upon the $etting Sun
through a long &amp; excellent Tele$cope,
there will not only appeare $trange ine-
qualities in the edge of it (in$omuch that
I have often $een it more indented than a
Saw) but tho$e inequalities will vani$h in
one place and pre$ently appeare in ano-
ther, and $eem perfectly to move like
waves $ucceeding and de$troying one an-
other; $ave that their Motion oftentimes
$eemes to be quicke$t as if in that va$t $ea
they were carried on by a current, or at
lea$t by a tide. And this (as we el$e
where note) appear's to the eye not on-
ly when it looks directly through the te-
<pb n=229>
le$cope upon the $unne; but al$o when a
large and well defin'd image of the $unne
is by the $ame tele$cope brought into a
roome and ca$t upon a $heet of white pa-
per. But to in$i$t on this were to digre$s:
and therefore I will proceed to experi-
ments of another kind.
<p>IT has been admir'd by very ingenious
<MARG><I>Experi-
ment</I> 31,</MARG>
Men, that if the exqui$itly poli$h'd
$urfaces of two flat peeces of marble be $o
congruous to each other that from their
mutuall application there will re$ult an
immediate contact, they will $tick $o fa$t
together, that he that lifts up the upper-
mo$t, $hall, if the undermo$t be not ex-
ceeding heavy, lift up that too, and $u$-
taine it aloft in the free aire. A proba-
ble cau$e of this $o clo$e adhe$ion we have
el$ewhere endeavour'd to deduce from the
unequall pre$$ure of the Air upon the un-
dermo$t $tone; For the lower <I>$uperficies</I>
of that $tone being freely expos'd to the
Air is pre$$'d upon by it, whereas the up-
permo$t $urface, being contiguous to the
$uperiour $tone, is thereby defended from
the pre$$ure of the Air which con$equent-
ly pre$$ing the lower $tone again$t the up-
<pb n=230>
per, hinders it from falling, as we have
el$ewhere more fully declar'd. Upon
the$e grounds we conjectur'd that in ca$e
we could procure two marbles exactly
ground to one another; and in ca$e we
could al$o $ufficiently evacuate our Re-
ceiver, the lower $tone would, for want
of the wonted and $u$taining pre$$ure of
the Air, fall from the upper. But the
further tryal of this Experiment we mu$t,
unle$s your Lord$hip think it worth Your
making at <I>Paris,</I> put off till a fitter
opportunity. For where we now are, we
cannot procure marbles $o exactly ground,
that they will $u$taine one another in the
Air, above a minute or two, which is a
much $horter time than the emptying of
our Receiver requires. We did indeed
try to make our marbles $tick clo$e to-
gether by moi$tening their polli$hed $ur-
faces with rectifi'd $pirit of Wine, in re-
gard that Liquor by its $udden avolation
from marble, if powr'd thereon, without
leaving it moi$t or le$s $mooth, $eem'd
unable to $u$taine them together after the
manner of a glutinous body, and yet
$eem'd $ufficient to exclude and keep out
the Air. But this we try'd to little pur-
po$e, for having convey'd into the Recei-
<pb n=231>
ver two black $quare marbles (the one of
two inches and a third in length or
breadth, and $omewhat more than halfe
an inch in thickne$s: The other of the $ame
extent, but not much above halfe $o
thick) fa$ten'd together by the interven-
tion of pure Spirit of Wine; and having
$u$pended the thicker by a $tring from the
cover, we found not that the ex$uction of
the ambient Air would $eparate them,
though a weight amounting to four oun-
ces were fa$ten'd to the lowermo$t mar-
ble to facilitate it's falling off.
<p>I would gladly have the Experiment
try'd with marble $o well polli$h't as to
need no Liquor what$oever to make them
cohere, and in a Ve$$el out of which the
Air may be more perfectly drawn than it
was out of ours. But in the mean time
though we will not determin whether the
Spirit of wine did contribute to the $trong
cohe$ion of the$e $tones, otherwi$e than
by keeping ev'n the $ubtl'$t parts of the
Air from getting in between them, yet it
$eemed that the not falling downe of the
lowermo$t marble might without impro-
bability be a$crib'd to the pre$$ure of the
Air remaining in the Receiver; which as
we formerly noted having been able
<pb n=232>
to keep a Cylinder of water of above
a Foot in height from falling to the bot-
tom of the Tube, may well enough be
$uppo$'d capable of keeping $o broad a flat
Marble from de$cending. And though this
may $eem a $trange proof of the $trength of
the $pring of Air, ev'n when rarified, yet it
will $carce $eem incredible to him that has
ob$erv'd how exceeding $trong a cohe$ion
may be made betwixt broad Bodies, one-
ly by their immediate touching one ano-
ther. A notable in$tance of which, I
have met with in this $hort Narrative of
<MARG><I>P. Nic.
Zucchius
opal Schot:
part</I> 1.
<*></MARG>
the Learned <I>Zucchius. Fuveni</I> ($ays he)
<I>lacertorum $uorum robur: jactanti propo-
$ita $emel e$t lamina &aelig;rea, per an$am in
medio extantem apprehen$am elevanda &egrave;
tabula marmorea, cui optime congruebat:
qui primo tanquam rem ludicr am puero
committendam contemp$it: tum in$tanti-
bus amicis manum utr&aacute;mque admovens,
cum luctatus diu h&aelig;rentem non removi$$et,
excu$avit impotentiam, objecta perigrini
&amp; potenti$simi glutinis interpo$itione, quo
forti$sime copulante nequiret divelli; do-
nec vidit ab alio per tabulam facilim&egrave; lami-
nam deduci, &amp; ad extrema product am, &amp;
actam in tran$ver$um in&agrave;e deportari.</I> But
that we may learn from our own Engine,
<pb n=233>
that two Bodies, though they touch each
other but in a $mall part of their $urfaces,
may be made to cohere very $trongly,
onely by this, That the Air pre$$es much
more forcibly upon the inferior $uperfi-
cies of the lowermo$t Body, then upon
the upper $urface of the $ame: We will
hereunto annex the following Experi-
ment, though out of the order wherein
they were made.
<MARG><I>Experi-
ment</I> 32.</MARG>
<p>I remember I have, in a Di$cour$e con-
cerning Fluidity and Firmne$s, made
mention of my having, by the ex$uction
of the Air out of a Gla$s Ve$$el, made
that Ve$$el take up, or $uck up (to $peak in
the common Language) a Body weighing
divers Ounces; but our Engine affording
us the opportunity of making con$ider-
abler Experiments of that kinde, We
thought fit to make a further tryal of the
force of the Atmo$phere's pre$$ure up-
wards, after the following manner.
<p>The Receiver having been exqui$itely
clo$'d, as we have often taught already,
and the Air being in a good mea$ure drawn
out of it, it was remov'd from off the
Pump: and to the lower Branch of the
<pb n=234>
Stop-cock, there was $peedily apply'd a
tapering Valve of bra$s, $uch as is de$crib'd
in the 9<SUP>th</SUP> fig: made fit to go with its nar-
rower end into the cavity of the branch,
and to fill the orifice of that cavity with
its broader part. And that the Air might
not get in at the litle intervals, left here
and there between the convex $urface of
the $topple and the internall edge of the
branch, tho$e intervals were $top't with
a little Diachylon. And to the doore,
or, (if you plea$e) that part of the Valve
which was to move to and fro, and in
this Experiment hung perpendicular to
the Horizon, there was, at a button of
bra$s belonging to the Valve fa$ten'd a
broad $cale wherein weights were to be
put. This done the key of the Stop-cock
was turn'd, and the externall Air beating
like a forcible $treame upon the Valve
to get in there, it did $uddenly both $hut
the Valve and keep it $hut $o $trongly,
that we had time to ca$t in diver$e weights
one after another into the Scale; till at
length the weight overpowering the pre$-
$ure of the Atmo$phere, drew downe the
Valve by the $tringes that ty'd the Scale
to it, and gave liberty to the outward Air
to ru$h into the Receiver. Though a-
<pb n=235>
nother time, when the Valve had but lit-
tle weight hanging at it, being, by I know
not what accident, drawn down beneath its
former place, it was by the impetuous
current of the outward Air $uddenly im-
pell'd up into it again, and kept there.
But in the former Experiment it is re-
markable, That though the Receiver were
not well exhau$ted, and though it leak'd
whil'$t the re$t of the Experiment was in
pro$ecution, and though the Valve
whereon the Cylinder of the Atmo$phere
could pre$s, were not above an Inch and
a half in Diameter, yet the weight kept
up by $uction, or rather $upported by the
Air, namely the Valve, the Seal and
what was ca$t into it, being $ent to be
weigh'd, amounted to about ten of our
common Pounds, con$i$ting of $ixteen
Ounces apiece: So that we doubted not
but that, had the Experiment been made
with favorable Circum$tances, the Air
endeavoring to pre$s in at the Orifice of
the Stop-cock, would have kept a very
much greater weight from falling out of
it; I $ay the Air, becau$e we found, by
tryal purpo$ely made, that neither the
imperfect contact of the Valve and the
Stop-cock, nor the Diachylon that was
<pb n=236>
employ'd to fill up the little Crannies left
betwixt them, were con$iderable in this
Experiment; by which may among other
things appear, that I did not without
cau$e in the above-nam'd Di$cour$e touch-
ing Fluidity and Firmne$s, a$cribe a great
force, ev'n to $uch Pillars of Air as may
be $uppo$'d to begin at the top of the
Atmo$phere, and recoyling from the
ground to terminate on the Bodies on
which they pre$s: $ince in the pre$ent Ex-
periment $uch a weight was $upported by
$o $lender a Cylinder of Air, rebounding
from the Earth to the Valve whereon it
did bear.
<p>BUt in regard we have not yet been
<MARG><I>Experi-
ment</I> 33.</MARG>
able to empty $o great a Ve$$el as our
Receiver, $o well as we can the Cylinder
it $elf; our Pump alone may afford us a
nobler in$tance of the fotce of the Air we
live in, in$omuch, that by help of this
part of our Engine, we may give a pretty
near ghe$s at the $trength of the Atmo-
$phere, computed as a weight. And the
way may be this; Fir$t, the Sucker be-
ing brought to move ea$ily up and down
the Cylinder, is to be impell'd to the top
<pb n=237>
of it: Then the Receiver mu$t be taken
off from the Pump, that the upper Ori-
fice of the Cylinder remaining open, the
Air may freely $ucceed the Sucker, and
therefore readily yield to its motion
downward. This done, there mu$t be
fa$ten'd to one of the Iron Teeth of the
Sucker, $uch a weight as may ju$t $uffice
to draw it to the bottom of the Cylinder.
And having thus examin'd what weight is
nece$$ary to draw down the Sucker, when
the Atmo$phere makes no other then the
ordinary re$i$tance of the Air again$t its
de$cent; the Sucker mu$t be again forc'd
to the top of the Cylinder, who$e upper
Orifice mu$t now be exactly clo$ed; and
then (the fir$t weight remaining) we ea$i-
ly may, by hanging a Scale to the above-
mention'd Iron (that makes part of the
Sucker) ca$t in known weights $o long,
till in $pight of the reluctancy of the At-
mo$phere the Sucker be drawn down. For
to the$e weights in the Scale, that of the
Scale it $elf being added, the $um will give
us the weight of a Column of Air, equal
in Diameter to the Sucker, or to the ca-
vity of the Cylinder; and in length to
the heighth of the Atmo$phere.
<p>According to this method we did, $ince
<pb n=238>
the writing of the la$t Experiment, at-
tempt to mea$ure the pre$$ure of the At-
mo$phere, but found it more difficult then
we expected, to perform it with any ac-
curatene$s; for though by the help of the
<I>Manubrium</I> the Sucker moved up and
down with $o much ea$e, that one would
have thought that both its convex $urface,
and the concave one of the Cylinder were
exqui$itely $mooth, &amp; as it were $lippery;
yet when the Sucker came to be moved
onely with a dead weight or pre$$ure (that
was not (like the force of him that
pump'd) intended as occa$ion required)
we found that the little rufne$$es, or other
inequalities, and perhaps too, the unequal
pre$$ure of the Leather again$t the cavity
of the Cylinder, were able now and then
to put a $top to the de$cent or a$cent of
the Sucker, though a very little external
help would ea$ily $urmount that impedi-
ment; and then the Sucker would, for a
while, continue its formerly interrupted
motion, though that a$$i$tance were with-
drawn. But this di$couragement did not
deterre us from pro$ecuting our Experi-
ment, and endeavoring, by a careful trial,
to make it as in$tructive as we could.
We found then that a Leaden Weight,
<pb n=239>
of 28 pounds (each con$i$ting of $ixteen
Ounces) being fa$tned to one of the teeth
of the Sucker, drew it down $lowly e-
nough; when the upper Orifice of the
Cylinder was left open, though by the
help of Oyl and Water, and by the fre-
quent moving the Sucker up and down
with the <I>Manubrium,</I> its motion in the
Cylinder had been before purpo$ely faci-
litated. This done, the upper Orifice of
the Cylinder was very carefully and clo$e-
ly $topp'd, the Valve being likewi$e $hut
with its wonted Stopple well oyl'd, af-
ter the Sucker had been again impell'd
up to the top of the Cylinder. Then to
the precedent twenty eight pound, we
added a hundred and twelve pounds more,
which forcing down the Sucker, though
but lei$urely, we took off the twenty
eight pound weight; and being unable to
procure ju$t $uch weights as we would
have had, we hung on, in$tead of it, one
of fourteen pound, but found that, with
the re$t, unable to carry down the Sucker.
And to $atisfie our $elves, and the Spe-
ctators, that it was the re$i$tance of the
ambient Air that hinder'd the de$cent of
$o great a weight, after that we had try'd
that upon un$topping the Valve, and
<pb n=240>
thereby opening an acce$s to the external
Air, the Sucker would be immediately
drawn down: After this, I $ay, we made
this further Experiment, That having by
a Man's $trength forcibly depre$$'d the
Sucker to the bottom of the Cylinder,
and then fa$tned weights to the above-
named Iron that makes part of that Suc-
ker, the pre$$ure of the external Air find-
ing little or nothing in the cavity of the
evacuated Cylinder to re$i$t it, did pre-
$ently begin to impell the Sucker, with
the weights that clogg'd it, towards the
upper part of the Cylinder, till $ome
$uch accidental Impediment as we former-
ly mention'd, check'd its cour$e; and
when that rub, which ea$ily might be, was
taken out of the way, it would continue
its a$cent to the top, to the no $mall won-
der of tho$e By $tanders, that could not
comprehend how $uch a weight could a$-
cend, as it were, of it $elf; that is, with-
out any vi$ible force, or $o much as Su-
ction to lift it up. And indeed it is very
con$iderable, that though po$$ibly there
might remain $ome particles of Air in the
Cylinder, after the drawing down of the
Sucker; yet the pre$$ure of a Cylinder of
the Atmo$phere, $omewhat le$s then
<pb n=241>
three Inches in Diameter (for, as it was
$aid in the de$cription of our Engine, the
cavity of the Cylinder was no broader)
was able, uncompre$$'d, not only to $u$tain,
but even to drive up a weight of an hun-
dred and odde pounds: for be$ides the
weight of the whole Sucker it $elf, which
amounts to $ome pounds, the weights an-
nexed to it made up a hundred and three
pounds, be$ides an Iron Bar, that by con-
jecture weighed two pounds more; and
yet all the$e together fall $omewhat $hort
of the weight which we lately mention'd,
the re$i$tance of the Air to have held $u-
$pended in the cavity of the Cylinder.
<p>And though (as hath been already ac-
knowledg'd) we cannot, peradventure,
obtain by the recited means $o exact an
account as were to be wi$h'd, of what we
would di$cover: Yet, if it $erve us to
ground Conjectures more approaching to
the Truth, then we have hitherto met
with, I hope it will be con$ider'd (which
a famous Poet judiciou$ly $ays)
<C><I>E$t quoddam prodire tenus, $i non da-
tur ultra.</I></C>
<p>Peradventure it will not be imperti-
<pb n=242>
nent to annex to the other Circum$tances
that have been already $ee down concern-
ing this Experiment, That it was made in
Winter, in Weather neither Fro$ty nor
Rainy, about the change of the Moon,
and at a place who$e latitude is near about
51<SUP>d</SUP> and a half: For perhaps the force or
pre$$ure of the Air may vary, according
to the Sea$ons of the Year, the tempera-
ture of the Weather, the elevation of the
Pole, or the pha$es of the Moon; all, or
even any of them $eeming capable to al-
ter either the heighth or con$i$tence of the
incumbent Atmo$phere: And therefore
it would not be ami$s if this Experiment
were carefully tryd at $everal times and
places, with variety of Circum$tances. It
might al$o be try'd with Cylinders of $e-
veral Diameters, exqui$itely fitted with
Suckers, that we might know what pro-
portion $everal Pillars of the Atmo$phere
bear, to the Weights they are able to $u-
$tain or lift up; and con$equently, whe-
ther the increa$e or decrement of the re-
$i$tance of the ambient Air, can be re-
duc'd to any regular proportion to the
Diameters of the Suckers: The$e, and
divers other $uch things which may be
try'd with this Cylinder, might mo$t of
<pb n=243>
them bemore exactly try'd by the To<*>-
cellian Experiment, if we could get Tubes
$o accurately blown and drawn, that the
Cavity were perfectly Cylindrical.
<p>To dwell upon all the $everal Refle-
ctions, that a $peculative Wit might
make upon this and the foregoing Expe-
riment: (I mean the thirty third and thir-
ty $econd, would require almo$t a Vo-
lume, whereas our occa$ions will $carce
allow us time to touch upon three or
four of the chief Inferences that $eem de-
ducible from them, and therefore we $hall
content our $elves to point at tho$e
few.
<p>And fir$t, as many other <I>Ph&aelig;nomena</I>
of our Engine, $o e$pecially, the two
lately mention'd Experiments, $eem ve-
ry much to call in que$tion the receiv'd
Opinion of the Nature or Cau$e of Su-
ction. For 'tis true indeed, that when men
$uck, they commonly u$e $ome manife$t
endeavour by a peculiar motion of their
Mouthes, Che$ts, and $ome other con$pi-
ring parts, to convey to them the body
to be $uckt in. And hence perhaps they
have taken occa$ion, to think that in all
<pb n=244>
Suction there mu$t be $ome Endeavour
or motion in the $ucking to attract the
$ucked Body. But in our la$t Experi-
ment it appeares not at all how the up-
per part of the empty'd Cylinder that re-
maines movele$s all the while, or any
part of it, does at all endeavour to draw
to it the depre$$ed Sucker and the an-
nex'd weights. And yet tho$e that be-
hold the a$cention of the Sucker, without
$eriou$ly con$idering the cau$e of it, doe
readily conclude it to be ray$'d by $ome-
thing that powerfully Sucks or attracts
it, though they $ee not what that may
be or where it lurks. So that it $eemes
not ab$olutely nece$$ary to Suction, that
there be in the Body, which is $aid to $uck,
an endeavor or motion in order thereun-
to, but rather that Suction may be at lea$t
for the mo$t part reduc'd to Pul$ion, and
its effects a$crib'd to $uch a pre$$ure of
the neighboring air upon tho$e Bodies
(whther a&euml;rial, or of other Natures) that
are contiguous to the Body that is $ayd to
attract them, as is $tronger than that Sub-
$tance which po$$e$$es the cavity of that
$ucking Body is able to re$i$t. To ob-
ject here, that it was $ome particles of
Air remaining in the empty'd Cylin-
<pb n=245>
der that attracted this weight to obviate
a <I>Vacuum,</I> will $carce be $atisfactory; un-
le$s it can be cleerly made out by what li-
tle hooks, or other grappling In$truments,
the internal Air could take hold of the
Sucker; how $o litle of it obtain'd the
force to lift up $o great a weight; and why
al$o, upon the letting in of a litle more
Air into one of our evacuated Ve$-
$els, the attraction is, in$tead of being
$trengthen'd, much weaken'd, though,
if there were danger of a <I>Vacuum</I> be-
fore, it would remain, notwith$tanding
this ingre$s of a little Air. For that $till
there remain'd in the capacity of the ex-
hau$ted Cylinder $tore of little rooms,
or $paces empty or devoid of Air, may
appear by the great violence wherewith
the air ru$hes in, if any way be open'd to it.
And that 'tis not $o much the decrement
of the <I>Vacuum</I> within the cavity of the
ve$$el that debilitates the attraction, as the
$pring of the included air (who$e pre$ence
makes the decrement) that does it by
re$i$ting the pre$$ure of the external Air,
$eems probable, partly from the Di$abi-
lity of vacuities, whether greater or le$$er,
to re$i$t the pre$$ure of the Air; and part-
ly by $ome of the <I>Ph&aelig;nomena</I> of our Ex-
<pb n=246>
periments, and particularly by this Cir-
cum$tance of the three and Thirtieth,
that the Sucker was by the pre$$ure of the
Ambient Air impell'd upwards, with its
weight hanging at it, not only when it
was at the bottome of the Cylinder, and
con$equently left a great <I>Vacuum</I> in the
cavity of it; but when the Sucker had
been already impel'd almo$t to the top of
the Cylinder, and con$equently, when the
<I>Vacuum</I> that remain'd was become very
litle in compari$on of that which preceded
the beginning of the Sucker's a$cention.
<p>In the next place, the$e Experiments
may teach us, what to judge of the vul-
gar Axiom receiv'd for $o many Ages
as an undoubted Truth in the Peripate-
tick Schools; That Nature abhorres
and flys a <I>Vacuum,</I> and that to $uch a de-
gree, that no humane power (to go no
higher) is able to make one in the Uni-
ver$e; wherein Heaven and Earth would
change places, and all its other Bodyes
rather act contrary to their own Nature,
than $uffer it. For, if by a <I>Vacuum</I> we
will under$tand a place perfectly devoid
of all corporeal Sub$tance, it may be in-
deed then, as we formerly noted be plau-
$ibly enough maintain'd, that there is
<pb n=247>
no $uch thing in the world; but that the
generality of the Pleni$ts, (e$pecially till
of late yeares $ome of them grew more
wary) did not take a <I>Vacuum</I> in $o $trict
a Sen$e, may appear by the Experiments
formerly, and ev'n to this Day imploy'd
by the Deniers of a Vacuum, to prove it
impo$$ible that there can be any made.
For when they alleadge (for In$tance)
that when a man $ucks Water through a
long Pipe, that heavy Liquor, contrary
to its Nature, a$cends into the Sucker's
mouth, only, to fill up that room made
by the Dilatation of his Bre$t and
Lungs, which otherwi$e will in part be
empty. And when they tell us, that the
rea$on why if a long Pipe exactly
clos'd at one end be fill'd top-ful
of Water, and then inverted, no Liquor
will fall out of the open Orifice; Or, to
u$e a more familiar Example, when they
teach, that the cau$e why in a Gardiner's
watering Pot $hap'd conically, or like a
Sugar-Loaf fill'd with Water, no Liquor
fals down through the numerous holes
at the bottome, whil$t the Gardiner keeps
his Thumb upon the Orifice of the litle
hole at the top, and no longer, mu$t be
that it in the ca$e propo$ed the Water
<pb n=248>
$hould de$cend, the Air being unable to
$ucceed it, there would be left at the up-
per and de$erted part of the Ve$$el a <I>Va-
cuum,</I> that would be avoided if the hole
at the top were open'd. When (I $ay)
they alleadge $uch Experiments, the
Tendency of them $eems plainly to im-
port, that they mean, by a <I>Vacuum,</I> any
$pace here below that is not fill'd with a
vi$ible body, or at lea$t with Air; though
it be not quite devoy'd of all Body what-
$oever. For why $hould Nature, out of
her dete$tation of a <I>Vacuum,</I> make Bo-
dies act contrary to their own Tendency,
that a place may be fill'd with Air, if its
being $o were not nece$$ary to the avoi-
ding of a <I>Vacuum.</I>
<p>Taking then a <I>Vacuum</I> in this vulgar
and obvious $ence, the common opinion
about it $eems lyable to $everal Exce-
ptions, whereof $ome of the chief are
$ugge$ted to us by our Engine.
<p>It will not ea$ily then be intelligibly
made out, how hatred or aver$ation,
which is a pa$$ion of the Soule, can either
for a <I>Vacuum,</I> or any other object, be $up-
pos'd to be in Water, or $uch like inani-
mate Body, which cannot be pre$um'd
to know when a <I>Vacuum</I> would en$ue; if
<pb n=249>
they did not be$tirre them$elves to pre-
vent it, nor to be $o generous as to act
contrary to what is mo$t conducive to
their own particular pre$ervation for the
publique good of the Univer$e. As much
then of intelligible and probable Truth,
as is contain'd in this Metaphoricall Ex-
pre$$ion, $eems to amount but to this;
That by the Wi$e Author of Nature
(who is ju$tly $ayd to have made all
things in number, weight, and mea$ure,)
the Univer$e, and the parts of it, are $o
contriv'd, that it is as hard to make a <I>Va-
cuum</I> in it, as if they $tudiou$ly con$pir'd
to prevent it. And how far this it $elfe
may be granted, de$erves to be further
con$ider'd.
<p>For in the next place, our Experiments
$eem to teach, that the $uppo$ed Aver$a-
tion of Nature to a <I>Vacuum</I> is but acci-
dental, or in con$equence partly of the
Weight and Fluidity, or, at lea$t, Fluxi-
lity of the Bodies here below; and partly,
and perhaps principally, of the Spring of
the air, who$e re$tle$s endeavor to expand
it $elfe every way, makes it either ru<*>h
in it $elfe, or compel the interpos'd bo-
dys into all $paces, where it finds no grea-
ter re$i$tance than it can $urmount. And
<pb n=250>
that in tho$e motions which are made <I>ob-
fugamVacui</I> (as the common phra$e is) Bo-
dys act without $uch genero$ity &amp; Con-
$ideration, as is wont to be a$crib'd to
them, is apparent enough in our 32<SUP>d</SUP> Ex-
periment, where the torrent of Air, that
$eem'd to $trive to get into the Empty'd
Receiver, did plainly prevent its own
De$igne, by $o impelling the Value, as
to make it $hut the only Orifice the Air
was to get in at. And if afterwards ei-
ther Nature, or the internal Air, had a de-
$igne the external Air $hould be attra-
cted, they $eem'd to pro$ecute very un-
wi$ely by continuing to $uck the Valve
$o $trongly, when they found that by
that Sucction the Valve it $elfe could not
be drawn in: Whereas by forbearing to
$uck, the Valve would by it's own weight
have fall'n down, and $uffer'd the exclu-
ded Air to returne freely, and to fill
again the exhau$ted Ve$$el.
<p>And this minds me to take notice of
another deficiency, pointed at by our Ex-
periments in the common Doctrine of
tho$e Pleni$ts we rea$on with; for many
of tho$e unu$ual motions in Bodies, that
are $ayd to be made to e$cape a <I>Vacuum,</I>
$eem rather made to fill it. For why,
<pb n=251>
to in$tance in our newly mention'd Ex-
periment, a$$oon as the Valve was de-
pre$s'd by the weight we hung at it,
$hould the Air $o impetuou$ly and copi-
ou$ly ru$h into the cavity of the Receiver;
if there were before no vacant room there
to receive it? and if there were, then all the
while the Valve kept out the Air, tho$e
litle $paces in the Receiver, which the
corpu$cles of that Air afterwards fill'd,
may be concluded to have remain'd em-
pty. So that the $eeming violence,
imploy'd by Nature on the occa$ion of
the evacuating of the Ve$$el, $eems to
have come too late to hinder the making
of Vacuities in the Receiver, and only
to have, a$$oon as we permitted, fill'd
up with Air tho$e that were already
made.
<p>And as for the Care of the Publique
Good of the Univer$e a$crib'd to dead
and $tupid Bodies, wee $hall only de-
mand, why in our 19<SUP>th</SUP> Experiment, upon
the Ex$uction of the ambient Air, the
Water de$erted the upper half of the
Gla$s-Tube; and did not a$cend to fill
it up, till the external Air was let in upon
it: whereas by its ea$y and $udden regai-
ning that upper part of the Tube, it
<pb n=252>
appear'd both that there was there much
$pace devoid of Air, and that the Water
might with $mall or no re$i$tance have
a$cended into it, if it could have done $o
without the impul$ion of the readmitted
Air; which, it $eems, was nece$$ary to
mind the Water of its formerly neglected
Duty to the Univer$e.
<p>Nay, for ought appeares, ev'n when
the excluded Air, a$$oon as 'twas per-
mitted, ru$ht violently into our exhau-
$ted Receiver, that flowing in of the
Air proceeded rather from the deter-
minate Force of the Spring of the
neighbouring Air, then from any endea-
vour to fill up, much le$s to prevent va-
cuity's. For though when as much Air as
will, is gotten into our Receiver our pre-
$ent Opponents take it for granted that
it is full of Air; yet if it be remembred
that when we made our 17<SUP>th</SUP> Experiment
we crouded in more Air to our Receiver
than it u$ually holds; and if we al$o con-
$ider (which is much more) the Air of
the $ame con$i$tence with that in our
Receiver may in wind guns, as is known,
and as we have try'd, be compre$$ed at
lea$t into halfe its wonted room (I $ay at
lea$t, becau$e $ome affirme, that the Air
<pb n=253>
may be thru$t into an 8<SUP>th</SUP>, or a yet $maller
part of its ordinary extent) it $eems ne-
ce$$ary to admit either a notion of conden-
$ation &amp; rarefaction that is not intelligi-
ble, or that in the capacity of our Recei-
ver when pre$um'd to be full of Air, there
yet remain'd as much of $pace as was ta-
ken up by all the a&euml;rial corpu$cles unpo$-
$e$$ed by the Air. Which $eemes plainly,
to infer that the Air that ru$h'd into our
empty'd ve$$el did not doe it preci$ely
to fill up the Vacuities of it, $ince it left $o
many unfill'd, but rather was thru$t in by
the pre$$ure of the contiguous Air; which
as it could not, but be always ready to ex-
pand it $elfe, where it found lea$t re$i-
$tance, $o was it unable to fill the Recei-
ver any more, then until the Air within
was reduc'd to the $ame mea$ure of Com-
pactne$s with that without.
<p>We may al$o from our two already of-
ten mention'd Experiments further de-
duce, that, ($ince Natures hatred of a
<I>Vacuum</I> is but Metaphorical and Ac-
cidental, being but a con$equence or re-
$ult of the pre$$ure of the Air and of the
Gravity, and partly al$o of the Fluxility
of $ome other bodies) The power $hee
makes u$e of to hinder a Vacuum, is not
<pb n=254>
(as we have el$e-where al$o noted) any
$uch boundle$s thing as men have been
pleas'd to imagine. And the rea$on, why
in the former Experiments, mentioned
in favour of the Pleni$ts, Bodies $eem to
forget their own Natures to $hun a <I>Va-
cuum,</I> $eems to be but this; That in the
alleadged ca$es the weight of that Wa-
ter that was either kept from falling or
impell'd up, was not great enough to
$urmount the pre$$ure of the contiguous
Air; which, if it had been, the Water
would have $ub$ided, though no Air could
have $ucceeded. For not to repeat that
Experiment of Mon$ieur <I>Pa$chal</I> (for-
merly mention'd to have been try'd in a
Gla$s exceeding 32 Foot) wherein the
inverted Pipe being long enough to con-
tain a competent weight of Water, that
Liquor freely ran out at the lower Orifice:
Not to mention this (I $ay) we $aw in
our nineteenth Experiment, that when
the pre$$ure of the ambient Air was $uffi-
ciently weaken'd, the Water would fall
out apace at the Orifice even of a $hort
Pipe, though the Air could not $ucceed
into the room de$erted by it. And it were
not ami$s if tryal were made on the tops
of very high Mountains, to di$cover with
<pb n=255>
what ea$e a <I>Vacuum</I> could be made near
the confines of the Atmo$phere, where
the Air is probably but light in compari-
$on of what it is here below. But our
pre$ent (three and thirtieth) Experiment
$eems to manife$t, not onely that the
power, exerci$'d by Nature, to $hun or re-
pleni$h a <I>Vacuum,</I> is limited, but that it
may be determin'd even to Pounds and
Ounces: In$omuch that we might $ay,
$uch a weight Nature will $u$tain or will
lift up to re$i$t a <I>Vacuum</I> in our Engine;
but if an Ounce more be added to that
weight, it will $urmount Her $o much
magnifi'd dete$tation of Vacuities. And
thus, My Lord, our Experiments may
not onely an$wer tho$e of the Pleni$ts,
but enable us to retort their Arguments
again$t them$elves: $ince, if that be true
which they alleadge, that, when Water
falls not down according to its nature, in
a Body wherein no Air can $ucceed to fill
up the place it mu$t leave, the $u$pen$i-
on of the Liquor is made <I>Ne detur Vacu-
um,</I> (as they $peak) it will follow, that
if the Water can be brought to $ub$ide
in $uch a ca$e, that de$erted $pace may be
deem'd empty, according to their own
Doctrine; e$pecially, $ince Nature (as
<pb n=256>
they would per$wade us) be$tirs her $elf
$o mightily to keep it from being de-
$erted.
<p>I hope I $hall not need to reminde Your
Lord$hip, that I have all this while been
$peaking of a <I>Vacuum,</I> not in the $trict
and Philo$ophical $en$e, but in that more
obvious and familiar one that has been
formerly declar'd.
<p>And therefore I $hall now proceed to
ob$erve in the la$t place, that our 33<SUP>d</SUP> Ex-
periment affords us a notable proof of the
unheeded $trength of that pre$$ure which
is $u$tain'd by the Corpu$cles of what we
call the free Air, and pre$ume to be un-
compre$$'d. For, as fluid and yielding a
Body as it is, our Experiment teaches us,
That ev'n in our Climate, and without
any other compre$$ion then what is (at
lea$t here below) Natural, or (to $peak
more properly) ordinary to it, it bears $o
$trongly upon the Bodies whereunto it is
contiguous, that a Cylinder of this free
Air, not exceeding three Inches in Dia-
meter is able to rai$e and carry up a
weight, amounting to between $ixteen
and $eventeen hundred Ounces. I $aid,
<pb n=257>
even in our Climate, becau$e that is tem-
<MARG><I>Aere $rig<*>-
do exi$tcate
tardius mo-
<*>entur Au-
tomat a qu&atilde;
acre ca<*>ida,
adco qui-
dem ut Au-
tomaton
quod Delg&aelig;
in Nova
Zembla a-
gentes in &aelig;-
dibus $u<*>s
collocave-
runt, omal-
no &agrave; motis
ce$$ave<*>it
<*>t$i m<*>
malus toa-
dus ei addidi$$ent quam antea ferre $olebat.</I> Varenius Geo: Genevat <*>.
111. Propo: 7. pag. 648.</MARG>
perate enough; and as far as my ob$er-
vations a$$i$t me to conjecture, the Air in
many other more Northern Countries
may be much thicker, and able to $upport
a greater weight: which is not to be
doubted of, if there be no mi$take in
what is Recorded concerning the <I>Hollan-
ders,</I> that were forc'd by the Ice to Win-
ter in <I>Nova Zembla,</I> namely, That
they found there $o conden$'d an Air, that
they could not make their Clock goe,
ev'n by a very great addition to the
weights that were wont to move it.
<p>I $uppo$e Your Lord$hip will readily
take notice, that I might very ea$ily have
di$cour$ed much more fully and accuratly
then I have done, again$t the common o-
pinion touching Suction, and touching na-
tures hatred of a <I>Vacuum.</I> But I was willing
to keep my $elf to tho$e con$iderations
touching the$e matters, that might be ve-
rifi'd by our Engine it $elf, e$pecially, $ince,
as I $aid at fir$t, it would take up too much
time to in$i$t particularly upon all the Re-
flections that may be made even upon our
two la$t Experiments. And therefore,
<pb n=258>
pa$$ing to the next, I $hall leave it to your
Lord$hip to con$ider how far the$e tryals
of ours will either confirm or disfavor
the new Doctrine of $everal eminent Na-
turali$ts, who teach, That in all motion
there is nece$$arily a Circle of Bodies, as
they $peak, moving together; and whe-
ther the Circles in $uch motion be an Ac-
cidental or Con$equential thing or no.
<p>TIs a known thing to tho$e that are con-
<MARG><I>Experi-
ment</I> 34.</MARG>
ver$ant in the Hydro$taticks, That
two Bodies which in the Air are of equal
weight, but of unequal bulk, as Gold,
for in$tance and Iron, being afterwards
weighed in Water, will lo$e their <I>&AElig;qui-
librium</I> upon the change of the ambient
Body, $o that the Gold will $ink lower
then the Iron; which, by rea$on of its
greater bulk, has more Water to lift
or di$place, that it may $ink. By Analogy
to this Experiment, it $eem'd probable,
that if two weights did in our Engine
ballance each other, when the Gla$s was
full of Air; upon the ex$uction of a
great part of that Air, $o notable a change
in the con$i$tence of the ambient Body,
<pb n=259>
would make them lo$e their <I>&AElig;quili-
brium.</I>
<p>But being de$irous at the $ame time to
make a tryal, for a certain De$ign that
needs not here be mention'd, we took
for one of our weights a dry Bladder,
$trongly tyed at the Neck, and about
half fill'd with Air (that being a weight
both $light, and that would expand it
$elf in the evacuated Gla$s) and fa$tning
that to one part of our formerly menti-
on'd exact ballance (which turns with the
32<SUP>d</SUP> part of a Grain) we put a Metalline
counterpoi$e into the oppo$ite Scale; and
$o the two weights being brought to an
<I>&AElig;quilibrium,</I> the ballance was convey'd
into the Receiver, and $u$pended from the
Cover of it.
<p>But before we proceed further, we mu$t
note, That pre$ently after the laying on
of the Cover, the Bladder appear'd to
preponderate, whereupon the Scales being
taken out, and reduc'd very near to an <I>&AElig;-
quilibrium,</I> yet $o, that a little advantage
remain'd on that $ide to which the Metal-
line weight belong'd; they were again let
down into the Receiver, which was pre-
$ently made fa$t with Plai$ter, and a hot
Iron: Soon after which, before the Pump
<pb n=260>
was employ'd, the Bladder $eem'd again
a little to preponderate. Afterwards
the Air in the Gla$s being begun to be
drawn out, the Biadder began (according
to the formerly mention'd Ob$ervations)
to expand it $elf, and manife$tly to out-
weigh the oppo$ite weight, drawing
down the Scale to which it was fa$tned
very much beneath the other, e$pecially
when the Air had $well'd it to its full ex-
tent.
<p>This done, we very lei$urely let in the
external Air; and ob$erv'd, that upon
the flagging of the Bladder, the Scale
whereto it was fa$tned, not onely by de-
grees return'd to an <I>&AElig;quilibrium</I> with the
other, but at length was a little out-
weighed by it.
<p>But becau$e we $u$pected there
might have interven'd $ome unheeded
Circum$tance in this la$t part of the Ex-
periment, we would not pre$ently take
out the Scales, nor meddle with the Co-
ver, but leaving things as they were, we
perceiv'd, that after a little while the
Bladder began again to preponderate, and
by degrees to $ink lower and lower for
divers hours; wherefore, leaving the
Ve$$el clo$'d up all night, we repair'd to it
<pb n=261>
next Morning, and found the Bladder
fallen yet lower. As if the very $ub$tance
of it, had imbibed $ome of the moi$ture
wherewith the Air (the Sea$on being ve-
ry rainy) did then abound: As Lute-
$trings, which are made likewi$e of the
Membranous parts of Guts, $trongly
wreath'd, are known to $well $o much,
oftentimes as to break in rainy and wet
weather. Which conjecture is the more to
beregarded, becau$e congruou$ly unto it
one of the company having a little warm'd
the Bladder, found it then lighter then
the oppo$ite weight. But this mu$t be
look'd upon as a bare conjecture, till we
can gain time to make further tryals about
it. In the mean while we $hall adde, that
without removing the Scales or the Co-
ver of the Receiver, we again cau$'d the
Air to be drawn out (the weather conti-
ing very moi$t) but found not any manife$t
alteration in the ballance; whether be-
cau$e the <I>&AElig;quilibrium</I> was too far lo$t to
let a $mall change appear, we determine
not.
<p>But to make the Experiment with a
Body le$s apt to be altered by the tempe-
rature of the Air, then was the Bladder;
we brought the Scales again to an <I>&AElig;qui-</I>
<pb n=262>
<I>librium</I> with two weights, whereof the
one was of Lead, the other of Cork. And
having evacuated the Receiver, we ob$er-
ved, that both upon the ex$uction, and
after the return of the Air, the Cork did
manife$tly preponderate, and much more
a while after the Air had been let in again,
then whil$t it was kept out. Wherefore,
in the room of the Cork, we $ub$tituted
a piece of Char-coal, as le$s likely to im-
bibe any moi$ture from the Air, but the
event proved much the $ame with that
newly related: So that this Experiment
$eems more liable to Ca$ualties then any,
excepting one we have made in our En-
gine. And as it is difficult to prevent
them, $o it $eems not very ea$ie to di$-
cover the cau$es of them, whereof we
$hall therefore at pre$ent forbear mention-
ing our Conjectures.
<p>SOme Learned Mathematicians have of
<MARG><I>Experi-
ment</I> 35.</MARG>
late ingenio&ugrave;$ly endeavored to reduce
Filters to <I>Siphons;</I> but $till the true cau$e
of the a$cen$ion of Water, and other Li-
quors, both in <I>Siphons</I> and in Filtration,
needing (for ought we have yet found) a
clearer Di$covery and Explication, we
<pb n=263>
were de$irous to try whether or no the
pre$$ure of the Air might rea$onably be
$uppo$'d to have either the principal, or at
lea$t a con$iderable Intere$t in the rai$ing
of tho$e Liquors. But becau$e we found
that we could not yet $o evacuate our Re-
ceiver, but that the remaining Air,
though but little in compari$on of the
exhau$ted, would be able to impell the
the Water to a greater height then is
u$ual in ordinary Filtrations: we re$olved,
in$tead of a Li$t of Cotton, or the like
Filtre, to make u$e of a <I>Siphon</I> of Gla$s,
delineated in the third Figure, con$i$t-
ing of three pieces, two $traight, and
the third crooked to joyn them toge-
ther; who$e Junctures were diligently
clo$'d, that no Air might finde entrance
at them. One of the Legs of this <I>Si-
phon</I> was (as it $hould be) $omewhat
longer then the other, and was pervious
at the bottom of it onely, by a hole al-
mo$t as $lender as a hair, that the
Water might but very lea$urely drop
out of it, le$t it $hould all run out
before the Experiment were compleat-
ed. The other and $horter Leg of
the <I>Siphon</I> was quite open at the end,
and of the $ame widene$$e with the
<pb n=264>
re$t of the Pipe, who$e bore was about <*>/4
of an Inch. The whole Siphon made
up of the$e $everal pieces put together,
was de$ign'd to be about a Foot and a
half long; that the remaining Air, when
the Ve$$el was exhau$ted after the wont-
ed manner, might not be able to impell
the Water to the top of the <I>Siphon;</I>
which being inverted, was fill'd with Wa-
ter, and of which the Shorter leg being
let down two or three Inches deep into a
Gla$s Ve$$el full of Water, and the up-
per parts of it being fa$ten'd to the in$ide
of the Cover of the Receiver, we pro-
ceeded to clo$e fir$t, and then to empty
the Ve$$el.
<p>The effect of the tryal was this, that
till a pretty quantity of Air had been
drawn out, the Water dropp'd freely out
at the lower end of the lower leg of the
<I>Siphon,</I> as if the Experiment had been
performed in the free Air. But afterwards,
the Bubbles (as had been apprehended)
began to di$clo$e them$elves in the Wa-
ter, and a$cending to the top of the <I>Si-
phon,</I> imbodyed them$elves there into
one, which was augmented little by little
by the ri$ing of other bubbles that from
time to time broke into it, but much
<pb n=278>
fir$t we thought might be $ome $tain up-
on the Gla$s; but after, finding it to
be in divers Qualities like the Oyl,
and Salt of the Concrete we were Di-
$tilling, we began to $u$pect that the
mo$t $ubtle and fugitive parts of the im-
petuou$ly a$cending Steams, had pene-
trated the $ub$tance (as they $peak) of
the Gla$s, and by the cold of the am-
bient Air were conden$'d on the $ur-
face of it. And though we were ve-
ry backward to credit this $u$pition, and
therefore call'd in an Ingenious Per$on
or two, both to a$$i$t us in the Ob-
$ervation, and have Witne$s of its e-
vent, we continued a while longer to
watch the e$cape of $uch unctuous Fumes,
and upon the whole matter unanimou$ly
concluded, That all things con$ider'd,
the $ubtle parts of the di$till'd matter
being violently agitated, by the exce$-
$ive heat had pa$$'d through the Pores
of the Gla$s, widen'd by the $ame heat.
But this having never happen'd but
once in any of the Di$tillations we have
either made or $een, though the$e be
not a few, it is much more rea$onable
to $uppo$e, that the perviou$ne$s of
our Receiver to a Body much more
<pb n=279>
$ubtle then Air, proceeded partly from
the loo$er Texture of that particular
parcel of Gla$s the Receiver was made
of (for Experience has taught us, that
all Gla$s is not of the $ame compact-
ne$s and $olidity) and partly from the
enormous heat, which, together with
the vehement agitation of the pene-
trant Spirits, open'd the Pores of the
Gla$s; then to imagine that $uch a
$ub$tance as Air, $hould be able to per-
meate the Body of Gla$s contrary to
the te$timony of a thou$and Chymical
and Mechanical Experiments, and of
many of tho$e made in our Engine, e-
$pecially that newly recited: Nay, by
our fifth Experiment it appears, that
a thin Bladder will not at its Pores
give pa$$age even to rarified Air. And
on this occa$ion we will annex an Ex-
periment, which has made $ome of
tho$e we have acquainted with it,
doubt, whether the Corpu$cles of the
Air be not le$$e $ubtle then tho$e of
Water.
<p>But without examining here the
rea$onablene$$e of that doubt, we will
proceed to recite the Experiment it $elf,
which $eems to teach, That though Air,
<pb n=280>
when $ufficiently compre$$'d, may per-
chance get entrance into narrower holes
and crannies then Water; yet unle$s the
Air be forc'd in at $uch very little holes,
it will not get in at them, though they
may be big enough to let Water pa$s
through them.
<p>The Experiment then was this: I took
a fair Gla$s <I>Siphon,</I> the lower end of
who$e longe$t Leg was drawn by degrees
to $uch a $lenderne$s, that the Orifice, at
which the Water was to fall out, would
hardly admit a very $mall Pin: This <I>Si-
phon</I> being inverted, the matter was $o
order'd, that a little Bubble of Air was
intercepted in the $lendere$t part of the
<I>Siphon,</I> betwixt the little hole newly men-
tion'd, and the incumbent Water, upon
which, it came to pa$s, that the Air be-
ing not to be forc'd through $o narrow a
pa$$age, by $o light a Cylinder of Water,
though amounting to the length of divers
Inches, as lean'd upon it, hinder'd the
further Efflux of the Water, as long as I
plea$'d to let it $tay in that narrow place:
whereas, when by blowing a little at the
wider end of the <I>Siphon,</I> that little par-
cel of Air was forc'd out with $ome Wa-
ter, the remaining Water, that before
<pb n=281>
continu'd $u$pended, began freely to drop
down again as formerly. And if you
take a Gla$s Pipe, whether it be in the
form of a <I>Siphon,</I> or no, that being for
the mo$t part of the thickne$s of a Mans
Finger, is yet towards one end $o $len-
der, as to terminate in a hole almo$t as
$mall as a Hor$e-hair; and if you fill this
Pipe with Water, you will finde that Li-
quor to drop down freely enough tho-
row the $lender Extream: But if you then
invert the Pipe, you will finde that the
Air will not ea$ily get in at the $ame hole
through which the Water pa$$'d. For in
the $harp end of the Pipe, $ome Inches
of Water will remain $u$pended, which
'tis probable would not happen, if the
Air could get in to $ucceed it, $ince if the
hole were a little wider, the Water would
immediatly $ub$ide. And though it be
true, that if the Pipe be of the length of
many Inches, a great part of the Wa-
ter will run down at the wider Orifice, yet
that $eems to happen for $ome other rea-
$on, then becau$e the Air $ucceeds it at
the upper and narrow Orifice, $ince all the
$lender part of the Pipe, and perhaps
$ome Inches more, will continue full of
Water.
<pb n=282>
<p>And on this occa$ion I remember, that
whereas it appears by our fifth Experi-
ment, That the A&euml;rial Corpu$cles (ex-
cept perhaps $ome that are extraordinari-
ly fine) will not pa$$e thorow the Pores
of a Lambs Bladder, yet Particles of Wa-
ter will, as we have long $ince ob$erv'd,
and as may be ea$ily try'd, by very clo$e-
ly tying a little <I>Alcalizate</I> Salt (we u$'d
the Calx of Tartar, made with Nitre)
in a fine Bladder, and dipping the lower
end of the Bladder in Water; for if you
hold it there for a competent while, you
will finde that there will $train thorow the
Pores of the Bladder Water enough to
di$$olve the Salt into a Liquor.
<p>But I $ee I am $lipt into a Digre$$ion,
wherefore I will not examine, whether,
the Experiment I have related, proceed-
ed from hence, That the $pringy Texture
of the Corpu$cles of the Air, makes
them le$s apt to yield and accommodate
them$elves ea$ily to the narrow Pores of
Bodies, then the more flexible Particles
of Water; or whether it may more pro-
babiy be a$crib'd to $ome other Cau$e.
Nor will I $tay to con$ider how far we may
hence be a$$i$ted to ghe$s at the cau$e of
the a$cen$ion of Water in the $lender
<pb n=283>
Pipes and <I>Siphons</I> formerly mention'd,
but will return to our Bubble; and take
notice, That we thought fit al$o to en-
deavor to mea$ure the capacity of the
Bubble we had made u$e of, by filling
it with Water, that we might the better
know how much Water an$wered in
weight to 3/4 of a Grain of Air, but not-
with$tanding all the diligence that was
u$ed to pre$erve $o brittle a Ve$$el, it
broke before we could perfect what we
were about, and we were not then pro-
vided of another Bubble fit for our
turn.
<p>The ha$te I was in, My Lord, when I
$ent away the la$t Sheet, made me forget
to take notice to you of a Problem that
occurr'd to my thoughts, upon the oc-
ca$ion of the $low breaking of the Gla$s
Bubble in our evacuated Receiver. For
it may $eem $trange, $ince by our $ixth
Experiment it appears, that the Air, when
permitted, will by its own internal Spring
expand it $elfe twice as much as <I>Mer-
$ennus</I> was able to expand it, by the
heat even of a candent <I>&AElig;olipile:</I> Yet
the <I>Elater</I> of the Air was $carce able to
break a very thin Gla$s Bubble, and ut-
<pb n=284>
terly unable to break one $omewhat thic-
ker, within who$e cavity it was impri-
$on'd; whereas Air pent up and agitated
by heat is able to perform $o much more
con$iderable effects, that (not to mention
tho$e of Rarefaction that are more obvi-
ous) the Learned Je$uit <I>Cab&aelig;us</I> (he that
<MARG><I><*>: Ni<*>:
<*>: lib:</I> 4.
<I><*> A-
<*></I></MARG>
writ of the Load-$tone) relates, That he
$aw a Marble Pillar ($o va$t, that three
men together with di$play'd arms could
not imbrace it, and that 1000 Yoke of
Oxen drawing it $everal ways with all
their $trength, could not have torn it
a$$under) quite broken off in the mid$t,
by rea$on of $ome Wood, which hap-
pening to be burnt ju$t by the Pillar, the
heat proceeding from the neighboring
Fire, $o rarified $ome Air or Spirituous
Matter which was $hut up in the cavities
of the Marble, that it broke through the
$olid Body of the Stone to obtain room
to expand it $elf.
<p>I remember I have taken notice that
probably the rea$on why the included Air
did not break the hermetically $eal'd Bub-
bles that remain'd intire in our emptyed
Receiver, was, That the Air, being $ome-
what rarefied by the Flame imploy'd to
clo$e the Gla$s, its Spring, upon the re-
<pb n=285>
ce$s of the heat, grew weaker then before.
But though we reject not that ghe$s, yet
it will not in the pre$ent ca$e $erve the
turn, becau$e that much $maller Gla$s
bubbles exactly clo$'d, will, by the in-
cluded Air (though agitated but by the
heat of a very moderate Fire) be made
to fly in pieces. Whether we may be
a$$i$ted to $alve this Problem, by con$i-
dering that the heat does from within ve-
hemently agitate the Corpu$cles of the
Air, and adde its a$$i$tance to the Spring
they had before, I $hall not now examine:
$ince I here but propo$e a Problem, and
that chiefly that by this memorable Story
of <I>Cab&aelig;us,</I> notice may be taken of the
prodigious power of Rarefaction, which
hereby appears capable of performing
$tranger things then any of our Experi-
ments have hitherto a$crib'd to it.
<p>We $hould hence, My Lord, imme-
diatly proceed to the next Experiment,
but that we think it fit, on this occa$ion,
to acquaint You with what $ome former
tryals (though not made in our Engine)
have taught us, concerning what we
would have di$cover'd by the newly
mention'd Bubble that broke. And this
the rather, becau$e (a great part of this
<pb n=286>
letter $uppo$ing the gravity of the Aire)
it will not be impertinent to determine
more particularly then hitherto we have
done, what gravity we a$cribe to it.
<p>We tooke then an <I>&AElig;olipile</I> made of
copper, weighing $ix ounces, five drachms,
and eight and forty graines: this being
made as hot as we dur$t make it, (for feare
of melting the mettle, or at lea$t the So-
dar) was removed from the fire and im-
mediately $topped with hard wax that no
Aire at all might get in at the little
hole wont to be left in <I>&AElig;olipiles</I> for the
fumes to i$$ue out at: Then the <I>&AElig;olipile</I>
being $uffer'd lea$urely to coole was again
weighed together with the wax that $topt
it, and was found to weigh (by rea$on of
the additionall weight of the wax) $ix
ounces, $ixe drachmes, and 39 graines.
La$tly, the wax being perforated without
taking any of it out of the Scale, the
externall Aire was $uffered to ru$h in
(which it did with $ome noy$e) and then
the <I>&AElig;olipile</I> and wax, being againe
weighed amounted to $ix ounces, $ix
drachmes, and 50. graines. So that the
<I>&AElig;olipile</I> freed as farre as our fire could
free it, from it's Aire, weighed le$$e then
<pb n=287>
it $elfe when repleni$hed with Air, full
eleven graines. That is, the Air contain-
able within the cavity of the <I>&AElig;olipile</I> a-
mounted to eleven graines and $omewhat
more; I $ay $omewhat more, becau$e of
the particles of the Air, that were not
driven by the fire out of the <I>&AElig;olipile.</I>
And by the way (if there be no mi$take
in the ob$ervations of the diligent <I>Mer-
$ennus</I>) it may $eeme $trange that it $hould
$o much differ from 2. or 3. of ours; in
none of which we could rarifie the Air in
our &AElig;<I>olipile</I> (though made red hot almo$t
all over, and $o immediately plung'd into
cold water) to halfe that degree which he
mentions, namely to 70. times it's natu-
rall extent, unle$$e it were that the <I>&AElig;o-
lipile</I> he imploy'd was able to $u$taine
a more vehement heat then ours (which
yet we kept in $o great an one, that once
the $oder melting, it fell a$under into the
two Hemi$pheres it con$i$ts of.)
<p>The fore-mentioned way of weighing
the Air by the help of an <I>&AElig;olipile,</I> $eems
$omewhat more exact then that which
<I>Mer$ennus</I> u$ed, In that in ours the <I>&AElig;oli-
pile</I> was not weighed, till it was cold;
whereas in his, being weighed red hot, it
<pb n=288>
$ubject to loo$e of it's $nb$tance in the
cooling, for (as we have el$ewhere noted
on another occa$ion) Copper heated red
hot is wont in the cooling to throw off
little thin $cales in $uch plenty, that having
purpo$ely watcht a Copper <I>&AElig;olipile</I> du-
ring its refrigeration, we have $een the
place round about it almo$t covered with
tho$e little $cales it had every way $cat-
ter'd: which, however they amount not
to much, ought not to be over-looked,
when 'tis $o light a body as Air, that is
to be weighed. We will not examine,
whether the &AElig;<I>olipile</I> in cooling may not
receive $ome little increment of weight,
either from the vapid or $aline Steames
that wander up and downe in the Air: But
we will rather mention, that (for the grea-
ter exactne$$e) we imployed to weigh our
<I>&AElig;olipile,</I> both when fill'd onely with Air
and when repleni$ht with Water, a paire
of $cales that would turne (as they $peak)
with the fourth part of a grain.
<p>As to the proportion of weight be-
twixt Air and Water, $ome learned men
have attempted it by wayes $o unaccurate
that they $eeme to have much mi$taken
it. For (not to mention the improbable
accounts of <I>Kepler</I> and others.) The l<*>ar-
<pb n=289>
ned and diligent <I>Ricciolus,</I> having pur-
po$ely endeavoured to inve$tigate this
proportion by meanes of a thin blad-
der, e$timates the weight of the Air to
that of the Water to be as one to ten
thou$and, or thereabouts. And indeed I re-
member that having formerly, on a cer-
tain occa$ion, weighed a large bladder full
of Air, and found it when the Air was all
$quee$ed out, to have contained fourteen
graines of Air. I found the $ame bladder
afterwards fill'd with water to containe
very neer 14. pound of that liquor: accor-
ding to which account, the proportion of
Air to Water was almo$t as a graine to a
pound, that is, as one to above 7600. To
this we may adde, that on the other $ide,
<I>Galileo</I> him$elfe u$ing another, but an un-
accurate way too, defined the Air to be
in weight to Water, but as one to 4. hun-
dred. But the way formerly propo$ed of
weighing the Air by an &AElig;<I>olipile,</I> $eemes
by great oddes more exact; and (as farre
as we could ghe$$e) $eemed to agree well
enough with the experiment made in our
Receiver. Wherefore it will be be$t to
tru$t our &AElig;<I>olipile</I> in the enquiry we are a-
bout, and according to our ob$ervations
the water it contained amounting to one
<pb n=290>
and twenty ounces and an halfe, and as
much Air as was requi$ite to fill it weigh-
ing eleven graines, the proportion in gra-
vity of Air to Water of the $ame bulk
will be as one to 938. And though we
could not fill the &AElig;<I>olipile</I> with water, $o
exactly as we would, yet in regard we
could not either as perfectly as we would,
drive the Air out of it by heat; we think
the proportion may well enough hold:
but tho$e that are delighted with round
numbers (as the phra$e is) will not be
much mi$taken if they reckon water to be
neere a thou$and times heavier than Air.
And (for further proof that we have made
the proportion betwixt the$e two bodies
rather greater then le$$er then indeed it is;
and al$o to confirme our former ob$erva-
tion of the weight of the Air) we will adde,
That, having another time put $ome Wa-
ter into the &AElig;<I>olipile</I> before we $et it on
the fire, that the copious vapours of the
rarefied liquor might the better drive out
the Air, we found, upon try all carefully
made, that when the &AElig;<I>olipile</I> was refrige-
rated, and the included vapours were by
the cold turned againe into water (which
could not have happen'd to the Air, that
the preceeding Steams expell'd) the Air,
<pb n=291>
when it was let in, increa$'d the weight of
the <I>&AElig;olipile</I> as much as before, namely,
Eleven Grains; though there were alrea-
dy in it twelve Drachmes and a half, be-
$ides a couple of Grains of Water, which
remain'd of that we had formerly put in-
to it to drive out the Air.
<p><I>Mer$ennus</I> indeed tells us, that by his
account Air is in weight to Water, as 1 to
1356. And adds, that we may, without
any danger, believe that the gravity of
Water to that of Air of a like bulk, is
not le$s then of 1300 to 1. And con$e-
quently, that the quantity of Air to a
quantity of Water equiponderant there-
to, is as 1300 to 1. But why we $hould
relinqui$h our own carefully repeated try-
als, I $ee not. Yet I am unwilling to re-
ject tho$e of $o accurate and u$eful a Wri-
ter: And therefore $hall propo$e a way
of reconciling our differing Ob$ervations,
by pre$enting, that the di$crepance be-
tween them may probably ari$e from the
differing con$i$tence of the Air at <I>London</I>
and at <I>Paris:</I> For our Air being more cold
and moi$t, then that which Your Lord-
$hip now breaths, may be $uppo$'d al$o
to be a fourth or fifth part more heavy. I
leave it to be con$ider'd, whether it be of
<pb n=292>
any moment that our Ob$ervations were
made in the mid$t of Winter, whereas his
were perhaps made in $ome warmer time
of the Year. But I think it were not a-
mi$s that, by the method formerly pro-
po$'d, the gravity of the Air were ob-
$erv'd both in $everal Countries, and in
the $ame Country, in the $everal Sea$ons
of the Year and differing Temperatures of
the Weather. And I would give $ome-
thing of value to know the weight of $uch
an <I>&AElig;olipile</I> as ours full of air in the mid$t
of Winter in <I>Nova Zembla,</I> if that be
true which we formerly took notice of,
namely, That the <I>Hollanders,</I> who Win-
tered there, found that Air $o thick that
their Clock would not go.
<p>If Your Lord$hip $hould now ask me,
if I could not by the help of the$e, and
our other Ob$ervations, decide the Con-
trover$ies of our Modern Mathematici-
ans about the height of the Air or Atmo-
$phere, by determining how high it doth
indeed reach: I $hould an$wer, That
though it $eems ea$ie enough to $hew that
divers Famous and Applauded Writers
have been mi$taken in a$$igning the heigth
of the Atmo$phere: Yet it $eems very
difficult preci$ely to define of what height
<pb n=293>
it is. And becau$e we have hitherto but
lightly touch'd upon a matter of $uch im-
portance, we pre$ume it wil not be thought
impertinent, upon this occa$ion, to annex
$omething towards the Elucidation of
it.
<p>What we have already try'd and newly
$et down, allows us to take it for granted,
that (at lea$t about <I>London</I>) the propor-
tion of gravity betwixt Water and Air,
of equal bulk, is as of a thou$and to
one.
<p>The next thing therefore that we are
to enquire after, in order to our pre$ent
de$ign, is the difference in weight betwixt
Water and Quick-$ilver: And though
this hath been defin'd already by the Il-
lu$trious <I>Verulam,</I> and $ome other inqui-
$itive Per$ons, that have compar'd the
weight of $everal Bodies, and ca$t their
Ob$ervations into Tables, yet we $hall
not $cruple to annex our own tryals about
it: Partly, becau$e we finde Authors
con$iderably to di$-agree; partly, becau$e
we u$'d exacter Scales, and a $omewhat
more wary method then others $eem to
have done: And partly al$o, becau$e ha-
ving pro$ecuted our inquiry by two or
three $everal ways; the $mall difference
<pb n=294>
between the events may a$$ure us that we
were not much mi$taken.
<p>We took then a Gla$s Pipe, of the
form of an inverted <I>Siphon,</I> who$e $hape
is delineated in the $ixteenth Figure: And
pouring into it a quantity of Quick $ilver,
we held it $o, that the $uperficies of the
Liquor, both in the longer and $horter
leg, lay in a Horizontal Line, denoted in
the Scheme by the prick'd Line EF; then
pouring Water into the longer Leg of the
<I>Siphon,</I> till that was almo$t fill'd, we ob-
$erv'd the $urface of the Quick-$ilver in
that leg to be, by the weight of the Wa-
ter, depre$$'d, as from E to B; and in
the $horter leg, to be as much impell'd
upward as from F to G: Whereupon ha-
ving formerly $tuck marks, as well at the
point B, as at the oppo$ite point D, we
mealur d both the di$tance DC to have
the height of the Cylinder of Quick-$il-
ver, which was rai$'d above the Point D
(level with the $urface of the Quick-$ilver
in the other leg) by the weight of the Wa-
ter, and the di$tance BA which gave us
the height of the Cylinder of Water. So
that the di$tance DC amounting to (2 1<*>/54)
Inches, and the height of the Water a-
mounting (30 45/51) Inches; and the whole
<pb n=295>
numbers on both $ides, which the annex-
ed Fractions being reduc'd to improper
Fractions of the $ame denomination, the
proportion appear'd to be (the denomi-
nators beng left out as equal on both $ides)
as 121 to 1665; or by reduction, as one
to (13 92/121).
<p>Be$ides this unu$ual way of determi-
ning the gravity of $ome things, we mea-
$ur'd the proportion betwixt Quick-$ilver
and Water, by the help of $o exact a bal-
lance, as loo$es its <I>&AElig;quilibrium</I> by the
hundredth part of a Grain. But becau$e
there is wont to be committed an over-
$ight in weighing Quick-$ilver and Wa-
ter, e$pecially if the Orifice of the Ve$$el
wherein they are put be any thing wide, in
regard that men heed not that the $urface
of Water in Ve$$els will be concave,
but that of Quick-$ilver, notably convex
or protuberant: To avoid this u$ual over-
$ight (I $ay) we made u$e of a gla$s bubble,
blown very thin at the Flame of a Lamp,
that it might not be too heavy for the
Ballance, and terminating in a very $lender
neck, wherein the concavity or convexity
of a Liquor could not be con$iderable:
This Gla$s weighing 23 1/2 Grains, we fill'd
<pb n=296>
almo$t with Quick-$ilver, and fa$tning a
mark over again$t the middle of the pro-
tuberant Superficies as near as our Eyes
could judge, we found that the Quick-
$ilver alone weighed 299 <*> Grains: Then
the Quick-$ilver being pour'd out, and
the $ame Gla$s being fill'd as full of com-
mon Water, we found the Liquor to
weigh 21 7/8 Grains. Whereby it appear'd
that the weight of Water to Quick-
$ilver, is as one to (13 19/28): Though our Il-
lu$trious <I>Verulam</I> (que$tionle$s not for
want of Judgement or Care, but of ex-
act In$truments) makes the proportion
betwixt tho$e two Liquors to be greater
then of 1 to 17. And to adde, that up-
on the by, $ince Quick-$ilver and well
rectified Spirit of Wine, are (how ju$tly
I $ay not) accounted, the one the hea-
vie$t, and the other the lighte$t of Li-
quors; we thought to fill in the $ame
Gla$s, and with the $ame Scales to ob-
$erve the difference betwixt them, which
we found to be as of 1 to (16 641/1084); where-
by it appear'd, That the difference be-
twixt Spirit of Wine, that may be made
to burn all away, ($uch as was ours) and
common Water, is as betwixt 1 and (1 44/171)
<pb n=297>
<p>We might here take occa$ion to ad-
mire, that though Water (as appear'd by
the Experiment formerly mention'd of
the Pewter Ve$$el) $eems not capable of
any con$iderable conden$ation, and $eems
not to have inter$per$'d in it any $tore of
Air; yet Quick-$ilver, of no greater bulk
then Water, $hould weigh near fourteen
times as much. But having onely point-
ed at this as a thing worthy of con$idera-
tion, we will proceed in our inquiry after
the heigth of the Atmo$phere: And to
avoid the trouble of Fractions, we will
a$$ume that Quick-$ilver is fourteen times
as heavy as Water, $ince it wants $o little
of being $o.
<p>Wherefore having now given us the
proportion of Air to Water, and Water
to Quick-$ilver, it will be very ea$ie to
finde the proportion betwixt Air and
Quick-$ilver, in ca$e we will $uppo$e the
Atmo$phere to be uniformly of $uch a
con$i$tence as the Air we weighed here
below. For $ince our Engine hath $uffi-
<MARG><*></MARG>
ciently manife$ted that 'tis the <I>&AElig;quili-
brium</I> with the external Air, that in the
<I>Torricellian</I> Experiment keeps the Quick-
$ilver from $ub$iding; And $ince, by our
accurate Experiment formerly mention'd,
<pb n=298>
it appears that a Cylinder of Mercury,
able to ballance a Cylinder of the whole
Atmo$phere, amounted to near about
thirty Inches; and $ince, con$equently
we may a$$ume the proportion of Quick-
$ilver to Air to be as fourteen thou$and to
one; it will follow, that a Cylinder of
Air, capable to maintain an <I>&AElig;quilibrium,</I>
with a Mercurial Cylinder of two Foot
and an half in height, mu$t amount to
35000 Feet of our Engli$h Mea$ure;
and con$equently (reckoning five Foot
to a Geometrical Pace, and one thou$and
$uch Paces to a Mile) to $even full
Miles.
<p>But this (as we lately intimated) pro-
ceeds upon the $uppo$ition, that the Air
is every where of the $ame con$i$tence
that we found it near the $urface of the
Earth; but that cannot with any $afety
be concluded, not onely for the rea$on I
finde to have been taken notice of by the
Antients, and thus expre$t in <I>Seneca:
Omnis A&euml;r</I> ($ays he) <I>quo propior e$t terris</I>
<MARG><*> 4.
<*> 10.</MARG>
<I>hoc cra$sior; quemadmodum in aqua &amp; in
omni humore f&aelig;x ima e$t, it a in A&euml;re $pi$-
$i&szlig;ima qu&aelig;&queacute; de$idunt;</I> but much more,
becau$e the $pringy Texture of the A&euml;rial
Corpu$cles, makes them capable of a
<pb n=299>
very great compre$$ion, which the weight
of the incumbent part of the Atmo-
$phere is very $ufficient to give tho$e that
be undermo$t and near the $urface of the
Earth. And if we recall to minde tho$e
former Experiments, whereby we have
manife$ted, That Air, much rarefied with-
out heat, may ea$ily admit a further ra-
refaction from heat; and that the Air, even
without being expanded by heat, is capa-
ble of being rarefied to above one hundred
and fifty times the extent it u$ually po$-
$e$$es here below; How can it be demon-
$trated that the Atmo$phere may not, for
ought we know, or at lea$t for ought can
be determin'd by our Statical and Mecha-
nical Experiments, ri$e to the height of
Five and twenty <I>German</I> Leagues, if not
of $ome hundred of common Miles?
<p>And this conjecture it $elf may appear
very injurious to the height whereunto
Exhalations may a$cend, if we will allow
<MARG><*></MARG>
that there was no mi$take in that $trange
Ob$ervation made at <I>Tolous</I> in a clear
Night in <I>Augu$t,</I> by the diligent Ma-
thematician <I>Emanuel Magnan,</I> and thus
Recorded by <I>Ricciolus,</I> (for I have not at
hand the Authors own Book) <I>Vidit</I> ($ays
he) <I>ab hor a undecima po$t meridiem u$&queacute; ad</I>
<pb n=300>
<I>mediam noctem Lun&acirc; infra horizontem
po$it&acirc;, nubeculam quandam lucidam prope
Meridianum fere u$que ad Zenith diffu$am
qu&aelig; con$ider at is omnibus non poter at ni$i &agrave;
$ole illuminari; ideoque altior e$$e debuit
tota umbr a terr&aelig;. Addit</I> (continues <I>Ricci-
olus) $imile quid eveni$$e Michaeli Angelo
Riccio apud Sabinos ver$anti nempe viro
in Mathe$i eruditi$simo.</I>
<p>Various Ob$ervations made at the
feet, tops, and interjacent parts of high
Mountains, might perchance $omewhat
a$$i$t us to make an e$timate in what pro-
portion, if in any certain one, the higher
Air is thicker then the lower, and ghe$s
at the di$-form con$i$tence, as to laxity
and compactne$s of the Air at $everal
di$tances from us. And if the difficul-
ties about the refractions of the Cele$tial
Lights, were $atisfactorily determin'd,
that might al$o much conduce to the pla-
cing due limits to the Atmo$phere (who$e
Dimen$ions tho$e Ob$ervations about
Refractions $eem hitherto much to con-
tract.) But for the pre$ent we dare not
pronounce any thing peremptorily con-
cerning the height of it, but leave it to
further inquiry: contenting our $elves to
have manife$ted the mi$take of divers
<pb n=301>
eminent Modern Writers, who will not
allow the Atmo$phere to exceed above
two or three Miles in height (as the Fa-
mous K<I>epler</I> will not the <I>A&euml;r refractivus</I>)
and to have rendred a rea$on why in the
mention we made in the Notes upon the
fir$t Experiment, touching the height of
the Atmo$phere, we $crupled not to $peak
of it, as if it might be many Miles high.
<p>WE will now proceed to recite a
<MARG><I>Experi-
ment</I> 37.</MARG>
<I>Ph&aelig;nomenon,</I> which, though
made among$t the fir$t, we thought fit
not to mention till after many others, that
we might have the opportunity to ob-
$erve as many Circum$tances of it as we
could, and $o pre$ent Your Lord$hip at
once, mo$t of what we at $everal times
have taken notice of concerning $o odde
a <I>Ph&aelig;nomenon.</I>
<p>Our Engine had not been long fini$h'd,
when, at the fir$t lea$ure we could $teal
from our occa$ions to make tryal of it,
we cau$'d the Air to be pump'd out of
the Receiver; and whil'$t I was bu$ied in
entertaining a Learned Friend that ju$t
then came to vi$it me, an Ingenious By-
<pb n=302>
$tander, thought he perceiv'd $ome new
kind of Light in the Receiver, of which
giving me ha$tily notice, my Friend and
I pre$ently ob$erv'd, that when the Suc-
ker was drawn down, immediately upon
the turning of the Key, there appear'd
a kinde of Light in the Receiver, almo$t
like a faint fla$h of Lightening in the
Day-time, and almo$t as $uddenly did it
appear and vani$h. Having, not with-
out $ome amazement, ob$erv'd divers
of the$e Apparitions of Light, we took
notice that the Day was clear, the hour
about ten in the Morning, that the onely
Window in the Room fac'd the North;
and al$o, that by interpo$ing a Cloak, or
any opacous Body between the Receiver
and the Window, though the re$t of the
Room were $ufficiently enlightned, yet
the fla$hes did not appear as before, un-
le$s the opacous Body were remov'd.
But not being able on all the$e Circum-
$tances to ground any firm Conjecture
at the cau$e of this $urpri$ing <I>Ph&aelig;nome-
non,</I> as $oon as Night was come, we
made the Room very dark; and plying
the Pump, as in the Morning, we could
not, though we often try'd, find, upon
the turning of the Key, $o much as the
<pb n=303>
lea$t glimmering of Light; whence we
inferr'd, that the fla$h appearing in the
Receiver, did not proceed from any new
Light generated there, but from $ome
reflections of the light of the Sun, or
other Luminous Bodies plac'd without
it; though whence that Reflection
$hould proceed, it po$'d us to conje-
cture.
<p>Wherefore the next Morning, ho-
ping to inform our $elves better, we
went about to repeat the Experiment,
but though we could as well as former-
ly exhau$t the Receiver, though the
place wherein we made the tryal was the
very $ame; and though other Circum-
$tances were re$embling, yet we could
not di$cover the lea$t appearance of
Light all that Day, nor on divers o-
thers on which tryal was again fruitle$-
ly made; nor can we to this very time
be $ure a Day before hand that the$e
Fla$hes will be to be $een in our great
Receiver. Nay, having once found the
Engine in a good humour (if I may
$o $peak) to $hew this trick, and $ent
notice of it to our Learned Friend
Doctor <I>Wallis,</I> who expre$$'d a great
<pb n=304>
de$ire to $ee this <I>Ph&aelig;nomenon,</I> though he
were not then above a Bow-$hoot off, and
made ha$te to $atisfie his Curio$ity; yet
by that time he was come, the thing he
came for was no longer to be $een; $o
that having vainly endeavored to exhibit
again the <I>Ph&aelig;nomenon</I> in his pre$ence, I
began to apprehend what he might think
of me, when unexpectedly the Engine
pre$ented us a fla$h, and after that a $econd,
and as many more, as $uffic'd to $atisfie
him that we might very well confidently
relate, that we have our $elves $een this
<I>Ph&aelig;nomenon,</I> though not confidently pro-
mi$e to $hew it others.
<p>And this un$ucce$sfulne$s whereto our
Experiment is lyable, being $uch, that by
all our watchfulne$s and tryals, we could
never reduce it to any certain Rules or
Ob$ervations; $ince in all con$titutions
of the Weather, times of the Day, <I>&amp;c.</I>
it will $ometimes an$wer, and $ometimes
di$-appoint our Expectations; We are
much di$courag'd from venturing to frame
an <I>Hypothe$is</I> to give an account of it:
which if the Experiment did con$tantly
$ucceed, might the more hopefully be at-
tempted; by the help of the following
<I>Ph&aelig;nomena</I> laid together: $ome of them
<pb n=305>
produc'd upon tryals purpo$ely made
to examine the validity of the conjectures,
other tryals had $ugge$ted.
<p>Fir$t then we ob$erv'd, that the Appa-
rition of Light may be made as well by
Candle-light, as by Day-light; and in
whatever po$ition the Candle be held, in
reference to the Receiver, as on this or
that hand of it, above it, beneath it, or
any other way, provided the Beams of
Light be not hinder'd from falling upon
the Ve$$el.
<p>Next, we noted that the fla$h appears
immediately upon the turning of the
Key, to let the Air out of the Receiver
into the empty'd Cylinder, in $o much
that I remember not that when at any
time in our great Receiver, the Stop-cock
was open'd before the Cylinder was ex-
hau$ted (whereby it came to pa$s that the
Air did rather de$cend, then ru$h into the
Cylinder) the often mention'd fla$h ap-
pear'd to our eyes.
<p>Yet, we further ob$erv'd, that when in-
$tead of the great Receiver we made u$e
of a $mall Gla$s, not containing above a
pound and a half of Water, the <I>Ph&aelig;no-
menon</I> might be exhibited though the
Stop-cock were open, provided the
<pb n=306>
Sucker were drawn nimbly down.
<p>We noted too, that when we began to
empty the Receiver, the appearances of
Light were much more con$picuous
then towards the latter end, when little
Air at a time could pa$s out of the Re-
ceiver.
<p>We ob$erv'd al$o, that when the Suc-
ker had not been long before well Oyl'd,
and in$tead of the great Receiver, the
$maller Ve$$el above-mention'd was em-
ploy'd; We ob$erv'd, I $ay, that then,
upon the opening of the Stop-cock, as
the Air de$cended out of the Gla$s in-
to the empty'd Cylinder, $o at the $ame
time there a$cended out of the Cylinder
into the Ve$$el a certain Steam, which
$eem'd to con$i$t of very little Bubbles,
or other minute Corpu$cles thrown up
from the Oyl, rarefied by the attrition it
$uffered in the Cylinder. For at the
$ame time that the$e Steams a$cended
into the Gla$s, $ome of the $ame kinde
manife$tly i$$ued out like a little Pillar of
Smoke at the Orifice of the Valve, when
that was occa$ionally open'd. And the$e
Steams frequently enough pre$enting
them$elves to our view, we found, by
expo$ing the Gla$s to a clear Light, that
<pb n=307>
they were wont to play up and down
in it, and $o by their whitei$hne$s, to e-
mulate in $ome mea$ure the apparition of
Light.
<p>For we likewi$e $ometimes found, by
watchful ob$ervation, that when the
Fla$h was great, not onely at the very
in$tant the Receiver lo$t of its tran$pa-
rency, by appearing full of $ome kinde
of whiti$h $ub$tance; but that for $ome
$hort time after the $ides of the Gla$s
continued $omewhat opacous, and
$eem'd to be darken'd, as if $ome
whiti$h Steam adher'd to the in$ide of
them.
<p>He that would render a Rea$on of
the <I>Ph&aelig;nomenon,</I> whereof all the$e are
not all the Circum$tances, mu$t doe
two things; whereof the one is diffi-
cult, and the other little le$s then im-
po$$ible: For he mu$t give an Ac-
count not onely whence the appearing
whitene$s proceeds, but wherefore that
whitene$s does $ometimes appear and
$ometimes not.
<p>For our part, we freely confe$$e
our $elves at a lo$$e about rendering
<pb n=308>
a Rea$on of the le$s difficult part of the
Problem: And though Your Lord-
$hip $hould ev'n pre$s us to declare what
Conjecture it was, that the above-recited
Circum$tances $ugge$ted to us, we $hould
propo$e the thoughts we then had, no o-
therwi$e then as bare Conjectures.
<p>In ca$e then our <I>Ph&aelig;nomenon</I> had con-
$tantly and uniformly appear'd, we $hould
have $u$pected it to have been produc'd
after $ome $uch manner as follows.
<p>Fir$t, we ob$erv'd that, though that
which we $aw in our Receiver $eem'd to
be $ome kinde of Light, yet it was indeed
but a whitene$s which did (as hath alrea-
dy been noted) opacate (as $ome $peak)
the in$ide of the Gla$s.
<p>Next we con$ider'd, that our com-
mon Air abounds with Particles or little
Bodies, capable to reflect the Beams of
Light. Of this we might ea$ily give di-
vers proofs, but we $hall name but two:
The one, that vulgar ob$ervation of the
Motes that appear in Multitudes $wim-
ming up and down in the Air, when the
Sun-beams $hooting into a Room, or any
other $hady Place di$cover them, though
otherwi$e the eye cannot di$tingui$h them
<pb n=309>
from the re$t of the Air: The other proof
we will take from what we (and no doubt
very many others) have ob$erv'd, touch-
ing the Illumination of the Air in the
Night. And we particularly remember,
that, being at $ome di$tance from <I>London</I>
one Night, that the People, upon a very
well-come Occa$ion, te$tified their Joy
by numerous Bon-fires; though, by rea-
$on of the Interpo$ition of the Hou$es,
we could not $ee the Fires them$elves, yet
we could plainly $ee the Air all enlighten'd
over and near the City; which argu'd,
that the lucid Beams $hot upwards from
the Fires, met in the Air with Corpu$cles
opacous enough to reflect them to our
Eyes.
<p>A third thing that we con$idered, was,
That white may be produc'd (without
excluding other ways, or denying invi$i-
ble Pores in the $olide$t Bodies) when
the continuity of a Diaphanous Body
happens to be interrupted by a great num-
ber of Surfaces, which, like $o many
little Looking-gla$$es, do confu$edly re-
pre$ent a multitude of little and $eeming-
ly contiguous Images of the elucid Body.
We $hall not in$i$t on the explanation of
this, but refer You for it to what we have
<pb n=310>
$aid in another Paper (touching Co-
lours.) But the In$tances that $eem to
prove it are obvious: For Water or whites
of Eggs beaten to froth, do lo$e their
tran$parency and appear white. And ha-
ving out of one of our le$$er Receivers
carefully drawn out the Air, and $o order'd
it, that the hole by which the Water was
to get in, was exceeding $mall, that the
Liquor might be the more broken in its
pa$$age thorow it, we ob$erv'd with plea-
$ure, That, the Neck being held under
Water, and the little hole newly men-
tion'd being open'd, the Water that ru$h'd
in was $o broken, and acquired $uch a mul-
titude of new Surfaces, that the Receiver
$eem'd to be full rather of Milk then Wa-
ter. We have likewi$e found out, That
by heating a lump of Cry$tal to a certain
degree, and quenching it in fair Water, it
would be di$continu'd by $uch a multi-
tude of Cracks, (which created new Sur-
faces within it) that though it would not
fall a$under, but retain its former $hape,
yet it would lo$e its tran$parency, and ap-
pear white.
<p>Upon the$e Con$iderations, My Lord,
and $ome others, it $eem'd not ab$ur'd to
imagine, That upon the ru$hing of the Air
<pb n=311>
out of the Receiver into the empty'd Cy-
linder, the Air in the Receiver being $ud-
denly and vehemently expanded, the Tex-
ture of it was as $uddenly alter'd, and the
parts made $o to $hift places (and perhaps
$ome of them to change po$tures) as du-
ring their new and vehement Motion and
their varied Scituation, to di$turb the
wonted continuity and $o the Diapha-
neity of the Air; which (as we have alrea-
dy noted) upon its cea$ing to be a tran-
$parent Body, without the interpo$ition
of colour'd things, mu$t ea$ily degene-
rate into white.
<p>Several things there were that made
this Conjecture $eem the le$s improba-
ble. As fir$t, That the whitene$s al-
ways appear'd greater when the Ex$ucti-
on began to be made, whil'$t there was
$tore of Air in the Receiver, then when
the Air was in great part drawn out. And
next, That, having exhau$ted the Re-
ceiver, and apply'd to the hole in the
Stop-cock a large bubble of clear Gla$s, in
$uch a manner, that we could at plea$ure let
the Air pa$s out at the $mall Gla$s into the
great one, and ea$ily fill the $mall one with
Air again, We ob$erv'd with plea$ure,
<pb n=312>
That upon the opening the pa$$age be-
twixt the two Gla$$es, the Air in the
$maller having $o much room in the great-
er to receive it, the Di$$ilition of that
Air was $o great, that the $mall Viol
$eem'd to be full of Milk; and this Expe-
riment we repeated $everal times. To
which we may adde, That, having pro-
vided a $mall Receiver, who$e upper Ori-
fice was $o narrow that I could $top it with
my Thumb, I ob$erv'd, that when upon
the Ex$uction of the Air the capacity of
the Gla$s appear'd white, if by a $udden
removal of my Thumb I let in the out-
ward Air, that whitene$s would imme-
diately vani$h. And whereas it may be
objected, That in the In$tance formerly
mention'd, Water turning from per$pi-
cuous to white, there intervenes the Air,
which is a Body of a Heterogeneous na-
ture, and mu$t turn it into Bubbles to
make it lo$e its tran$parency. We may
borrow an An$wer from an Experiment
we deliver in another Treati$e, where we
teach how to make two very volatile Li-
quors, which being gently put together
are clear as Rock-water, and yet will al-
mo$t in a moment, without the $ub-ingre$-
$ion of Air to turn them into Bubbles, $o
<pb n=313>
alter the di$po$ition of their in$en$ible
parts, as to become a white and con$i$tent
Body. And this happens not as in the
precipitation of <I>Benjamin,</I> and $ome o-
ther Re$inous Bodies, which being di$-
$olv'd in Spirit of Wine, may, by the effu-
$ion of fair Water, be turn'd into a $eem-
ingly Milky $ub$tance. For this white-
ne$s belongs not to the whole Liquor, but
to the Corpu$cles of the di$$olv'd Gum,
which after a while $ub$iding leave the Li-
quor tran$parent, them$elves onely re-
maining white: Whereas in our ca$e, 'tis
from the vary'd texture of the whole for-
merly tran$parent fluid Body, and not
from this or that part that this whitene$$e
re$ults: For the Body is white thorowout,
and will long continue $o; and yet may,
in proce$s of time, without any addition,
be totally reduc'd into a tran$parent Bo-
dy as before.
<p>But be$ides the Conjecture in$i$ted on
all this while, we grounded another upon
the following Ob$ervation, which was,
That having convey'd $ome $moke into
our Receiver plac'd again$t a Window, we
ob$erv'd, that upon the ex$uction of the
Air, the Corpu$cles that were $wimming
in it, did manife$tly enough make the Re-
<pb n=314>
ceiver $eem more opacous at the very
moment of the ru$hing out of the Air:
For con$idering that the whitene$s, who$e
cau$e we enquire of, did but $ometimes ap-
pear, it $eem'd not impo$$ible but that at
$uch times the Air in the Receiver might
abound with Particles, capable of re-
flecting the Light in the manner requi$ite
to exhibit a white colour, by their being
put into a certain unu$ual Motion. As
may be in $ome mea$ure illu$trated by
this, That the new motion of the fre$hly
mention'd Fumes, made the in$ide of the
Receiver appear $omewhat darker then
before: And partly by the nature of our
formerly mention'd $moking Liquor,
who$e parts though they $eem'd tran$pa-
rent whil'$t they compo$'d a Liquor, yet
when the $ame Corpu$cles, upon the un-
$topping of the Gla$s, were put into a
new motion, and di$po$'d after a new
manner, they did opacate that part of the
Air they mov'd in, and exhibited a great-
er whitene$s then that which $ometimes
appears in our Pneumatical Ve$$el. Nor
$hould we content our $elves with this $in-
gle In$tance, to manife$t, That little Bo-
dies, which being rang'd after one manner,
are Diaphanous and Colourle$s, may, by
<pb n=315>
being barely agitated, di$per$'d, and con-
$equently otherways rang'd, exhibite a
colour, if we were not unwilling to rob
our Collection of Experiments concern-
ing Colours.
<p>But, My Lord, I fore$ee You may
make $ome Objections again$t our pro-
po$ed ghe$s, which perhaps I $hall $carce
be able to an$wer, e$pecially, if You in-
$i$t upon having me render a Rea$on why
our <I>Ph&aelig;nomenon</I> appears not con$tant-
ly.
<p>I might indeed an$wer, that probably
it would do $o, if in$tead of our great
Receiver we u$e $uch a $mall Viol as we
have lat<I>e</I>ly mention'd, wherein the Di$$i-
lition of the Air being much greater, is
like to be the more con$picuous: Since I
remember not that we ever made our try-
al with $uch $mall Ve$$els, without find-
ing the expected whitene$s to appear. But
it would remain to be explicated, why in
our great Receiver the <I>Ph&aelig;nomenon</I> $hould
$ometimes be $een, and oftentimes not ap-
pear. And though that Conjecture which
we la$t made $hould not be rejected, yet if
we were further pre$$'d to a$$ign a rea$on
why the Air $hould abound with $uch Par-
ticles, as we there $uppo$e, more at one
<pb n=316>
time then another, we are not yet pro-
vided of any better An$wer, then this
general one, That the Air about us,
and much more that within the Receiver,
may be much alter'd by $uch cau$es as few
are aware of: For, not to repeat tho$e
probable Arguments of this A$$ertion
which we have occa$ionally mention'd
here and there in the former part of this
Epi$tle, we will here $et down two or
three In$tances to verifie the $ame Propo-
$ition. Fir$t, I finde that the Learned
<I>Fo$ephus Aco$ta,</I> among other Judicious
<MARG><*></MARG>
Ob$ervations he made in <I>America,</I> hath
this concerning the Effects of $ome
Winds; <I>There are</I> ($ays he) <I>Winds which
naturally trouble the Water of the Sea, and
make it green, and black; others, clear as
Cry$tal.</I> Next, we have ob$erv'd, That
though we conveyd into the Receiver our
Scales, and the <I>Pendula</I> formerly men-
tion'd, clean and bright; yet after the Re-
ceiver had been empty'd, and the Air let in
again, the glo$s or lu$tre both of the one,
and of the other, appear'd tarni$h'd by a
beginning ru$t. And in the la$t place, we
will $ubjoyn an Ob$ervation we made
$ome Years ago, which hath been heard
of by divers Ingenious Men, and $een
<pb n=317>
by $ome of them: We had, with pure
Spirit of Wine, drawn a Tincture out of
a certain Concrete which u$es to be rec-
koned among Mineral Bodies; And this
Tincture being very pure and tran$parent,
we did, becau$e we put a great value upon
it, put into a Cry$tal Viol which we care-
fully $topp'd, and lock'd up in a Pre$s a-
mong $ome other things that we $pecial-
ly priz'd. This Liquor being a Chy-
mical Rarity, and be$ides, very defecate
and of a plea$ing Golden Colour; we
had often occa$ion to look upon it, and
$o to take notice, that one time it $eem'd
to be very much troubled, and not clear
as it was wont to be: Whereupon we ima-
gined, that though it would be $omething
$trange, yet it was not impo$$ible that
$ome Precipitation of the Mineral Cor-
pu$cles was then happening, and that
thence the Liquor was opacated; but,
finding after $ome days that though the
expected Precipitation had not been
made, yet the Liquor, retaining its for-
mer vivid Colour, was grown clear again
as before; we $omewhat wondered at it,
and locking it up again in the $ame Pre$s,
we re$olved to ob$erve, both whether
the like changes would again appear in
<pb n=318>
our Tincture; and whether in ca$e they
$hould appear, they would be a$cribable
to the alterations of the Weather. But
though, during the greate$t part of a Win-
ter and a Spring, we took plea$ure to ob-
$erve, how the Liquor would often grow
turbid, and after a while clear again: Yet
we could not finde that the$e Mutations
depended upon any that were manife$t in
the Air, whieh would be often dark and
clouded, when the Tincture was clear and
tran$parent; as on the other $ide, in clear
Weather the Liquor would appear $ome-
times troubled, and more opacous. So
that being unable to give an account of
the$e odde changes in our Tincture (which
we $uppo$e we have not yet lo$t, though
we know not whether it have lo$t its fickle
Nature) either by tho$e of the Air, or
any thing el$e that occurr'd to our
thoughts; we could not but $u$pect that
there may be in divers Bodies, as it were
Spontaneous Mutations, that is, $uch
changes as depend not upon manife$t
Cau$es. But, My Lord, what has been
all this while $aid concerning our <I>Ph&aelig;no-
menon,</I> is offer'd to You, not as contain-
ing a $atisfactory Account of it, but to
a$$i$t You to give Your$elf one.
<pb n=319>
<p>WE took a Gla$s Ve$$el, open
<MARG><I>Experi-
ment</I> 38.</MARG>
at the top, and into it we put
a mixture of Snow and common Salt
($uch a mixture as we have in another
Treati$e largely di$cour$ed of) and in-
to the mid$t of this mixture we $et a
Gla$$e, of a Cylindrical form, clo$ely
$topp'd at the lower end with Plai$ter,
and open at the upper, at which we
fill'd it with common Water. The$e
things being let down into the Recei-
ver, and the Pump being $et awork,
the Snow began to melt $omewhat fa-
$ter then we expected; whether upon
the account of the Ex$uction of the
Air, or becau$e there was but little of
the Snow, or whether for any other
Rea$on, it appeared doubtfull. But
however, by that time the Receiver
had been con$iderably exhau$ted, which
was done in le$$e then 1/4 of an hour,
we perceived the Water near the bot-
tom of the Gla$s Cylinder to Freeze,
and the Ice by a little longer $tay, $eem'd
to encrea$e, and to ri$e $omewhat higher
<pb n=320>
then the $urface of the $urrounding Li-
quor, where into almo$t all the Snow and
Salt were re$olv'd. The Gla$s being ta-
ken out, it appear'd that the Ice was as
thick as the in$ide of the Gla$s it fill'd,
though into that I could put my Thumb.
The upper $urface of the Ice was very
concave, which whether it were due to
any unheeded accident, or to the ex$u-
ction of the Air, we leave to be deter-
min'd by further tryal. And la$tly, the
Ice held again$t the Light, appear'd not
de$titute of Bubbles, though $ome By-
$tanders thought they were fewer then
would have been found if the Water had
been frozen in the open Air. The like
Experiment we try'd al$o another time in
one of our $mall Receivers, with not un-
like $ucce$s.
<p>And on this occa$ion, My Lord, give
me leave to propo$e a Problem, which
$hall be this: Whence proceeds that
$trange force that we may $ometimes ob-
$erve in frozen Water, to break the Bo-
dies that Impri$on it, though hard and $o-
lid? That there is $uch a force in Wa-
ter expo$'d to Congelation, may be ga-
ther'd not onely from what may be often
ob$erv'd in Winter, of the bur$ting of
<pb n=321>
Gla$$es too clo$e $topp'd, fill'd with Wa-
ter or aqueous Liquors, but by In$tances
as much more con$iderable as le$s obvi-
ous. For I remember, that an Ingenious
Stone-cutter not long $ince complain'd to
me, That $ometimes, through the negli-
gence of Servants, the Rain being $uffer-
ed to $oak into Marble Stones, the $uper-
vening violent Fro$ts would bur$t the
Stones, to the Profe$$ors no $mall dam-
age. And I remember another Trades-
man, in who$e Hou$e I had Lodgings, was
la$t Winter complaining, that even Im-
plements made of Bell-metal, being care-
le$ly expo$'d to the wet, have been broken
and $poil'd by the Water, which, having
gotten into the little Cavities and Cran-
nies of the Metal, was there afterwards
frozen and expanded into Ice. And to
the$e Relations, we can adde one of the
<MARG><I>In <*>.</I> 4.
<*></MARG>
formerly mention'd <I>Cab&aelig;us's,</I> whereby
they not onely may be confirm'd, but are
$urpa$$'d: For he tells us, That he $aw a
huge Ve$$el of exceeding hard Marble,
$plit a$under by congel'd Water, who$e
Rarefaction, $ays our Author, prov'd $o
vehement, that the hardne$s of the Stone
yielded to it; and $o a Ve$$el was broken,
which would not have been $o by 100
<pb n=322>
Yoke of Oxen drawing it $everal ways. I
know, My Lord, that to $olve this Pro-
blem, it will be $aid, That Congelation
does not (as is commonly, but erroneou$ly
pre$um'd) reduce water into le$s room
then it po$$e$$'d before, but rather makes
it take up more. And I have el$ewhere
prov'd by particular Experiments, That
whether or no Ice may be truly $aid to be
Water rarefi'd (for that $eems que$tion-
able) it may be $aid to take up more room
then the Water did before Glaciation.
But though we grant that freezing makes
Water $well, yet, how Cold (which in
Weather-Gla$$es manife$tly condences
the Air) $hould expand either the Water,
or the intercepted Air $o forcibly, as to
perform $uch things as we have newly re-
lated, will yet remain a Problem.
<p>WE took an Oval Gla$s, clear and
<MARG><I>Experi-
ment</I> 39.</MARG>
(lea$t it $hould break) pretty
$trong, with a $hort Neck at the obtu$er
end, through this Neck, we thru$t almo$t
to the bottom, a Pipe of Gla$s, which was
clo$ely Cemented to the newly mention'd
Neck, the upper part of which Pipe,
was drawn in $ome places more $lender
<pb n=323>
then a Crows Quill, that the changes of
the Air in that. Gla$s Egge might be the
more con$picuous; Then there was con-
vey'd into the Gla$s five or $ix Spoon-
fulls of Water, part of which, by blow-
ing Air into the Egge, was rai$'d into the
above-mention'd $lender part of the Pipe,
$o that the Water was interpo$'d between
the external Air, and that included in the
Egge. This Weather-gla$s (delineated
in the fourteenth Figure) was $o plac'd,
and clo$'d up in the cavity of one of our
$mall Receivers, that onely the $lender
part of the Pipe, to the heigth of four
or five Inches, pa$$ing thorow a hole in
the Cover, remain'd expo$'d to the open
Air.
<p>The Pump being $et a work, upon
the Ex$uction of the Air, the Water in
the Pipe de$cended about a quarter of an
Inch, and this upon two or three reitera-
ted tryals; which $eem'd $ufficiently to
argue that there was no heat produc'd in
the Receiver upon the Ex$uction of the
Air: For even a little heat would pro-
bably have been di$cover'd by that Wea-
ther-gla$s, $ince upon the bare applica-
tion of my hand to the out$ide of the
Receiver, the warmth having after $ome
<pb n=324>
time been communicated or propagated
through both the Gla$$es, and the inter-
val betwixt them to the Impri$on'd Air,
did $o rarifie that, as to inable it, by pre$-
$ing upon the $ubjacent Water, to impel
that in the Pipe very many times as far as
it had fallen downwards upon the Ex$ucti-
on of the Air.
<p>Yet $hall not we conclude, that in the
cavity of the Receiver the cold was great-
er after the Ex$uction of the Air then be-
fore.
<p>For if it be demanded what then could
cau$e the fore-mention'd $ub$iding of the
Water? it may be an$wered, That pro-
bably it was the reaching of the Gla$s
Egge, which, upon the Ex$uction of the
ambient Air, was unable to re$i$t alto-
gether as much as formerly the pre$$ure of
the included Air, and of the Atmo$phere,
which by the interven$ion of the Water,
pre$$'d upon its concave $urface: Which
$eem'd probable, as well by what was a-
bove deliver'd, in the Experiment about
the breaking of the Gla$s by the force of
the Atmo$phere; as by this notable Cir-
cum$tance (which we divers times ob-
$erv'd) That when by drawing the Air out
of the Receiver, the Water in the Pipe
<pb n=325>
was $ub$ided, upon the readmi$$ion of the
external Air to pre$s again$t the convex
$urface of the Egge, the Water was pre-
$ently re-impell'd to its former height:
Which would perhaps appear le$s $trange
to Your Lord$hip, if You had yet $een
what we have heretofore taught in ano-
ther Treati$e concerning the Spring that
may be di$cover'd in Gla$s, as rigid and
inflexible a Body as it is generally e-
$teem'd. And in the mean while it may
$erve the turn to cau$e a Gla$s Egge to be
blown exceeding thin, and then, having
broken it, try how far you can by degrees
bend $ome narrow parts of it; and how
readily, upon the removal of what kept
it bent, it will re$tore it $elf to its former
$tate or po$ture. But to return to our
Experiment, From thence it $eems pro-
bable, either that there $ucceeds no Bo-
dy in the room of the Air drawn out of
our Receiver, or that it is not every Mat-
ter that is $ubtle enough readily to pa$s
through the Pores of Gla$s, that is al-
ways agitated enough to produce Heat
where ever it is plentifully found. So that
if no <I>Vacuum</I> be to be admitted, this Ex-
periment $eems to invite us to allow a
great di$parity, either as to bulk, or as to
<pb n=326>
agitation, or as to both, betwixt $ome
parts of the Etherial Sub$tance, and tho$e
that are wont here below to produce Heat
and Fire.
<p>We try'd al$o what Operation the
drawing out of the Air would have upon
Camphire, that being a Body, which,
though not a Liquor, con$i$ts of $uch
Volatile or Fugitive parts, that without
any greater agitation then that of the open
Air it $elf, they will copiou$ly flie away.
But we found not that even this loo$e
Body was $en$ibly alter'd by the Ex$ucti-
on of the ambient Air.
<p>IT may $eem well worth trying, whether
<MARG><I>Experi-
ment</I> 40.</MARG>
or no in our exhau$ted Gla$s the want
of an ambient Body, of the wonted thic-
ne$s of Air, would di$able even light and
little Animals, as Bees, and other winged
In$ects, to flie. But though we ea$ily
fore$aw how difficult it would be to make
$uch an Experiment; yet not to omit our
endeavors, we procur'd a large Fle$h-fly,
which we convey'd into a $mall Receiver.
We al$o another time $hut into a great
Receiver a Humming Bee, that appear'd
$trong and lively, though we had rather
<pb n=327>
have made the tryal with a Butter-fly, if
the cold Sea$on would have permitted us
to finde any. <note><I>Since the writing of this
XLth Experiment, we pro-
cur'd a wbite Butter-Fly,
and inclo$'d it in one of our
$maller Receivers, where,
though at fir$t he fluttered
up and down, yet pre$ently,
upon the ex$uction of the
Air, he fell down as <*>
$woon, retaining no other
motion then $ome little <*>-
bling of the wings.</I></note> The Fly, af-
ter $ome Ex$uctions of the
Air, dropp'd down from the
$ide of the Gla$s whereon $he
was walking: But, that the
Experiment with the Bee
might be the more in$tructive,
we convey'd in with her a bun-
dle of Flowers, which re-
main'd $u$pended by a $tring
near the upper part of the Receiver: And
having provok'd the Bee, we excited her
to flie up and down the capacity of the
Ve$$el, till at length, as we de$ir'd, $he
lighted upon the Flowers; whereupon
we pre$ently began to draw out the Air,
and ob$erv'd, That though for $ome time
the Bee $eem'd to take no notice of it, yet
within awhile after $he did not flie, but fall
down from rhe Flowers, without appear-
ing to make any u$e of her Wings to help
her $elf. But whether this fall of the Bee,
and the other In$ect, proceeded from the
mediums being too thin for them to flie in,
or barely from the weakne$s, and as it were
$wooning of the Animals them$elves, you
will ea$ily gather from the following Ex-
periment.
<pb n=328>
<p>TO $atisfie our $elves in $ome mea$ure,
<MARG><I>Experi-
ment</I> 41.</MARG>
about the account upon which Re$pira-
tion is $o nece$$ary to the Animals, that
Nature hath furni$h'd with Lungs, we
took (being then unable to procure any
other lively Bird, $mall enough to be put
into the Receiver) a Lark, one of who$e
Wings had been broken by a $hot, of a
Man that we had $ent to provide us $ome
Birds for our Experiment; but notwith-
$tanding this hurt, the Lark was very
lively, and did, being put into the Recei-
ver, divers times $pring up in it to a good
height. The Ve$$el being ha$tily, but
carefully clo$'d, the Pump was diligently
ply'd, and the Bird for a while appear'd
lively enough; but upon a greater Ex-
$uction of the Air, $he began manife$tly
to droop and appear $ick, and very $oon
after was taken with as violent and irregu-
lar Convul$ions, as are wont to be ob-
$erv'd in Poultry, when their heads are
wrung off: For the Bird threw her $elf
over and over two or three times, and dy-
ed with her Brea$t upward, her Head
downwards, and her Neck awry. And
though upon the appearing of the$e Con-
<pb n=329>
vul$ions, we turn'd the Stop-cock, and
let in the Air upon her, yet it came too
late; whereupon, ca$ting our eyes upon
one of tho$e accurate Dyals that go with
a <I>Pendulum,</I> and were of late ingeniou$ly
invented by the Noble and Learned <I>Hu-
genius,</I> we found that the whole Tragedy
had been concluded within ten Minutes of
an hour, part of which time had been im-
ploy'd in cementing the Cover to the Re-
ceiver. Soon after we got a Hen-$par-
row, which being caught with Bird-lime
was not at all hurt; when we put her into
the Receiver, almo$t to the top of which
$he would briskly rai$e her $elf, the Ex-
periment being try'd with this Bird, as it
was with the former, $he $eem'd to be
dead within $even minutes, one of which
were imploy'd in cementing on the Co-
ver: But upon the $peedy turning of the
Key, the fre$h Air flowing in, began $low-
ly to revive her, $o that after $ome pant-
ings $he open'd her eyes, and regain'd her
feet, and in about a 1/4 of an hour, after
threatned to make an e$cape at the top of
the Gla$s, which had been un$topp'd to
let in the fre$h Air upon her: But the Re-
ceiver being clo$'d the $econd time, $he
<pb n=330>
was kill'd with violent Convul$ions,
within five Minutes from the beginning
of the Pumping.
<p>A while after we put in a Mou$e, new-
ly taken, in $uch a Trap as had rather af-
frighted then hurt him; vvhil'$t he vvas
leaping up very high in the Receiver, vve
fa$ten'd the Cover to it, expecting that
an Animal u$ed to live in narrow holes
vvith very little fre$h Air, vvould endure
the vvant of it better then the lately men-
tion'd Birds: But though, for a vvhile af-
ter the Pump vvas $et avvork, he conti-
nued leaping up as before; yet 'tvvas not
long ere he began to appear $ick and gid-
dy, and to $tagger, after vvhich he fell
dovvn as dead, but vvithout $uch violent
Convul$ions as the Birds died vvith.
Whereupon, ha$tily turning the Key, we
let in $ome fre$h Air upon him, by vvhich
he recovered, after a vvhile, his $en$es and
his feet, but $eem'd to continue vveak and
$ick: But at length, grovving able to
skip as formerly, the Pump vvas plyed
again for eight minutes, about the mid-
dle of vvhich $pace, if not before, a very
little Air by a mi$chance got in at the
Stop-cock; and about tvvo minutes after
that, the Mou$e divers times leap'd up
<pb n=331>
lively enough, though after about two mi-
nutes more he fell down quite dead, yet
with Convul$ions far milder then tho$e
wherewith the two Birds expired. This
alacrity $o little before his death, and his
not dying $ooner then at the end of the
eighth minute, $eem'd a$cribable to the
Air (how little $oever) that $lipt into the
Receiver. For the fir$t time, tho$e Con-
vul$ions (that, if they had not been $ud-
denly remedied, had immediately di$-
patch'd him) $ei$'d on him in $ix minutes
after the Pump began to be $et awork.
The$e Experiments $eem'd the more
$trange, in regard, that during a great part of
tho$e few minutes the Engine could but
con$iderably rarefie the Air (and that too,
but by degrees) and at the end of them
there remain'd in the Receiver no incon-
$iderable quantity; as may appear by what
we have formerly $aid of our not being
able to draw down Water in a Tube, with-
in much le$s then a Foot of the bottom:
with which we likewi$e con$ider'd, that by
the ex$uction of the Air and inter$per-
$ed Vapors, there was left in the Recei-
ver a $pace $ome hundreds of times ex-
ceeding the bigne$s of the Animal, <*>e-
ceive the fuliginous Steams, from which,
<pb n=332>
expiration di$charges the Lungs; and,
which in the other ca$es hitherto known,
may be $u$pected, for want of room, to
$tifle tho$e Animals that are clo$ely pent
up in too narrow Receptacles.
<p>I forgot to mention, that having cau$'d
the$e three Creatures to be open'd, I
could, in $uch $mall Bodies, di$cover lit-
tle of what we $ought for, and what we
might po$$ibly have found in larger Ani-
mals; for though the Lungs of the Birds
appear'd very red, and as it were inflam'd,
yet that colour being u$ual enough in the
Lungs of $uch winged Creatures, de$erves
not $o much our notice, as it does, That
in almo$t all the de$tructive Experiments
made in our Engine, the Animals appear'd
to die with violently Convul$ive Moti-
ons: From which, whether Phy$icians can
gather any thing towards the Di$covery
of the Nature of Convul$ive Di$tem-
pers, I leave to them to con$ider.
<p>Having proceeded thus far, though (as
we have partly intimated already) there
appear'd not much cau$e to doubt, but
that the death of the fore-mention'd Ani-
mals proceeded rather from the want of
Air, then that the Air was over-clogg'd
by the $teams of their Bodies, exqui$ite-
<pb n=333>
ly pent up in the Gla$s; yet I, that love
not to believe any thing upon Conje-
ctures, when by a not over-difficult Ex-
periment I can try whether it be True or
no, thought it the $afe$t way to obviate
Objections, and remove Scruples, by $hut-
ting up another Mou$e as clo$e as I could
in the Receiver, wherein it liv'd above
three quarters of an hour; and might pro-
bably have done $o much longer, had not
a <I>Virtuo$o</I> of quality, who in the mean
while chanc'd to make me a Vi$it, de$ir'd
to $ee whether or no the Mou$e could be
kill'd by the ex$uction of the ambient Air,
whereupon we thought fit to open, for a
little while, an intercour$e betwixt the
Air in the Receiver, and that without it,
that the Mou$e might thereby (if it were
needful for him) be refre$h d, and yet we
did this without uncementing the Cover
at the top, that it might not be objected,
that perhaps the Ve$$el was more clo$ely
$topp'd for the ex$uction of the Air then
before.
<p>The Experiment had this event, that
after the Mou$e had liv'd ten Minutes,
(which we a$crib'd to this, that the Pump,
for want of having been lately Oyl'd,
could move but $lowly, and could not by
<pb n=334>
him that manag'd it, be made to work as
nimbly as it was wont) at the end of that
time he dy'd with Convul$ive Fits, where-
in he made two or three bounds into the
Air, before he fell down dead.
<p>Nor was I content with this, but for
Your Lord$hips further $atisfaction, and
my own, I cau$'d a Mou$e, that was very
hungry, to be $hut in all Night, with a
Bed of Paper for him to re$t upon: And
to be $ure that the Receiver was well
clo$'d, I cau$'d $ome Air to be drawn out
of it, whereby, perceiving that there
was no $en$ible leak, I pre$ently re-ad-
mitted the Air at the Stop-cock, le$t the
want of it $hould harm the little Animal;
and then I cau$'d the Engine to be kept
all Night by the Fire $ide, to keep him
from being de$troy'd by the immoderate
cold of the Fro$ty Night. And this care
$ucceeded $o well, that the next Morning
I found that the Mou$e not onely was a-
live, but had devour'd a good part of the
Chee$e that had been put in with him. And
having thus kept him alive full twelve
hours, or better, we did, by $ucking out
part of the Air, bring him to droop, and
to appear $well'd; and by letting in the
Air again, we $oon reduc'd him to his for-
mer liveline$s.
<pb n=335>
<C><I>A Digre$sion containing $ome
Doubts touching Re$pi-
ration.</I></C>
<p>I Fear Your Lord$hip will now expect,
that to the$e Experiments I $hould add
my Reflections on them, and attempt,
by their a$$i$tance, to re$olve the Diffi-
culties that occur about Re$piration; $ince
at the beginning I acknowledg'd a further
Enquiry into the Nature of that, to have
been my De$ign in the related Tryals.
But I have yet, becau$e of the inconve-
nient Sea$on of the Year, made $o few
Experiments, and have been $o little $a-
tisfied by tho$e I have been able to make,
that they have hitherto made Re$piration
appear to me rather a more, then a le$s
My$terious thing, then it did before. But
yet, $ince they have furni$h'd me with
$ome $uch new Con$iderations, concern-
ing the u$e of the Air, as confirms me in
my Diffidence of the Truth of what is
commonly believ'd touching that matter;
That I may not appear $ullen or lazy, I
am content not to decline employing a
<pb n=336>
few hours in $etting down my Doubts, in
pre$enting Your Lord$hip $ome Hints,
and in con$idering whether the Tryals
made in our Engine, will at lea$t a$$i$t us
to di$cover wherein the Deficiency lies
that needs to be $upply'd.
<p>And this, My Lord, being all my pre-
$ent De$ign, I $uppo$e You will not ex-
pect that (as if You knew not, or had for-
gotten what Anatomi$ts are wont to
teach) I $hould entertain You with a need-
le$s Di$cour$e of the Organs of Re$pira-
tion, and the variety of their Structure in
$everal Animals; though if it were ne-
ce$$ary, and had not been perform'd by o-
thers, I $hould think, with <I>Galen,</I> that by
<MARG><I>Galen<*> de
<*>, Part:
<*></I> 3.</MARG>
treating of the Fabricks of living Bodies,
I might compo$e Hymns to the wi$e Au-
thor of Nature, who, in the excellent con-
trivance of the Lungs, and other parts of
(tho$e admirable Engines) Animals, ma-
nife$ts him$elf to be indeed what the Elo-
quent Prophet mo$t ju$tly $peaks him,
<I>Wonderful in Counsel, and excellent in</I>
<MARG><*>a.28.29.</MARG>
<I>working.</I>
<p>Nor $hall we any further meddle with
tho$e Controver$ies $o much agitated a-
mong the Moderns, namely, <I>Whether the
motion of the Lungs in Re$piration be their</I>
<pb n=337>
<I>own, or but con$equent to the motion of the
Thorax, Diaphragme, and</I> (as $ome Learn-
ed Men would have it) <I>the Abdomen; And,
Whence it is that the Air $wells the Lungs
in In$piration</I> any further then they may
receive light from our Engine: But that
it may appear what kinde of $ervice it is
that may be expected from it on this oc-
ca$ion, we mu$t premi$e a few Words to
$hew wherein the $trength of the Obje-
ction we are to an$wer, lies. In favor then
of tho$e that would have the Lungs ra-
ther pa$$ive then active in the bu$ine$s of
Re$piration, it may again$t the common
opinion be alledg'd, That as the Lungs be-
ing de$titute of Mu$cles and of Fibres,
are unfit to dilate them$elves; $o it ap-
pears, that without the motion of the
<I>Thorax</I> they would not be fill'd with Air.
Since as our Learned Friend Dr. <I>High-
more</I> has well (and congruou$ly, to what
our $elves have purpo$ely try'd) ob-
$erv'd, if a live Dog have a great wound
made in his Che$t, the Lobes of the
Lungs on that $ide of the <I>Media$ti-
num</I> will $ub$ide and lie $till; the <I>Tho-
rax</I> and the Lobes on the other $ide
of the <I>Media$tinum,</I> continuing their
former motion. And if $uddenly at once
<pb n=338>
the Mu$cles of the Che$t be on both
$ides di$$ected, upon the Ingre$s of the
Air, the whole Lungs, though untouch'd,
will remain movele$s, at lea$t, as to any ex-
pan$ion or contraction of their $ub$tance.
<p>To which we may adde the Ob$ervati-
on of the diligent <I>Bartholinus,</I> who af-
firms the like of the <I>Diaphragme</I> al-
$o, namely, That it being wounded, the
Lungs will fall together, and the Re$pi-
ration cea$e, which my Experiments op-
po$e not, provided the Wound be any
thing great. And indeed the <I>Diaphragme</I>
$eems the principal In$trument of ordina-
ry and gentle Re$piration, although to
re$train'd Re$piration (if I may $o call
it) the interco$tal Mu$cles, and perhaps
$ome others may be allowed eminently to
concur. But the chief of the Contro-
ver$ies formerly pointed at, is not yet de-
cided, namely, what it is that conveys the
Air into the Lungs. For when, to coun-
terballance all that has been alledg'd, tho$e
that plead for the Lungs, demand what it
is that $hould bring the Air into the
Lungs, if them$elves do not attract it,
their Antagoni$ts di$agree about the Re-
ply. For when to this que$tion $ome of
the be$t Modern Philo$ophers an$wer,
<pb n=339>
that by the dilatation of the Che$t the
contiguous Air is thru$t away, and that
pre$$ing upon the next Air to it, and $o
onwards, the Propul$ion is continued till
the Air be driven into the Lungs, and $o
dilate them: When this (I $ay) is an-
$wered, it is Objected even by <I>Bartholine</I>
him$elf, as a convincing Reply, that, ac-
cording to this Doctrine, a Man could not
fetch his Breath from a great Ve$$el full of
Air, with a $lender Neck, becau$e, that
when his Mouth covers the Orifice of the
Neck, the dilatation of his <I>Thorax</I> could
not propell the Air in the Ve$$el into his
Lungs, by rea$on of its being $eparated
by the inclo$ing Ve$$el from the ambient
Air; and yet, $ay they, Experience wit-
ne$$es that out of $uch a Ve$$el a Man may
$uck Air. But of this difficulty our Engine
furni$hes us with an ea$ie Solution, $ince
many of the former Experiments have ma-
nife$ted, That in the ca$e propo$ed, there
needs not be made any (though 'tis true
that in ordinary Re$piration there is wont
to be made $ome) propul$ion of the Air by
the $welling <I>Thorax</I> or <I>Abdomen</I> into the
Lungs; $ince upon the bare Dilatation of
the <I>Thorax,</I> the Spring of that internal
Air, or halituous $ub$tance that is wont
<pb n=340>
to po$$e$s as much of the Cavity of the
Che$t as the Lungs fill not up, being much
weaken'd, the external and contiguous
Air mu$t nece$$arily pre$s in at the open
Winde-Pipe into the Lungs, as finding
there le$s re$i$tance then any where el$e a-
bout it.
<p>And hence (by the way) we may derive
a new a$$i$tance to judge of that famous
Controver$ie di$puted among Naturali$ts
and Phy$itians, ever $ince <I>Galens</I> time,
$ome maintaining that the Che$t, with the
contained Lungs, may be re$embled to a
pair of Bellows, which comes therefore
to be fill'd becau$e it was dilated: And o-
thers pleading to have the compari$on
made to a Bladder, which is therefore di-
lated becau$e it is fill'd. For as to the
<I>Thorax,</I> it $eems evident from what has
been lately $aid, that it, like a pair of Bel-
lows, happens to be partly fill'd with Air,
but becau$e it was dilated: But as for the
Lungs them$elves, who want Fibres to
di$tend them, they may fitly enough be
compar'd to a Bladder; $ince they are di-
lated by being fill'd, namely, by that Air
which ru$hes into them upon the dilatation
of the Che$t, in who$e increa$ed Cavity
it findes (as we fre$hly noted) le$s re$i$t-
<pb n=341>
ance to its Spring then el$ewhere. And
this brings into my minde that $trange
Ob$ervation of <I>Nicolaus Fontanus,</I> a Phy-
<MARG><I>Fontan<*>
apud</I> <*>
tholin<*>
cap. 9.</MARG>
$itian at <I>Am$terdam,</I> who te$tifies, That
in a Boy of the $ame Town, four years
old, there was found, in$tead of Lungs, a
certain Membranous Bladder; which be-
ing fill'd with Wind, and furni$h'd with
little Veins, had its origination from the
Wind-Pipe it $elf; which being $uppo$'d
true, how well it will agree with mo$t of
the Opinions touching Re$piration, I leave
to be con$idered.
<p>And thus may the grand Objection of
<I>Bartholine,</I> and others, be an$wered: But
I leave to Anatomi$ts to con$ider what is
to be $aid to $ome Ob$ervations that $eem
to contradict tho$e Anatomical Experi-
ments already mention'd: Such was par-
ticularly that which I remember I have
read in <I>Sennertus</I> (from the ob$ervation of
his Father-in-law <I>Schato</I>) of a Melancho-
ly Student, who having $tabb'd him$elf,
and pierced the <I>Diaphragme</I> in the thinner
or tendonous part (call'd by many the
Nervous Circle) lived $even Moneths af-
ter he had $o wounded him$elf, though af-
ter his death (preceded by violent Vomit-
<pb n=342>
ings) the Wound (perchance dilated by
tho$e $trainings) appear'd $o great, that
the whole Stomack was found to have got
in by it into the left $ide of the <I>Thorax.</I>
And $uch al$o was the accident that hap-
pen'd to a Noble Man, whom I remem-
ber I have $een, and who is yet alive, in
who$e Che$t there has, for the$e many
years, remain'd a hole $o great, that the
motion of his Heart may be perceiv'd by
it. The$e (I $ay) and $ome other Ob$er-
vations, I $hall now forbear to in$i$t on,
becau$e I hold it not unfit, before we
come to con$ider the u$e of Re$piration,
that we acquaint Your Lord$hip with an
Ingenious Conjecture, that was made at
the cau$e of the ha$ty death of the Ani-
mals our Engine kill'd: namely, That it
was not the want of Air that de$troy'd
them, but the Pre$$ure of the innate Air
in the cavity of the Che$t; as if the
Spring of this Air being no longer coun-
terballanc'd by the ambient Air, was there-
by become $o $trong, that it kept the
<I>Thorax</I> forcibly di$tended, and hinder'd its
wonted contraction; and $o compre$$'d
the Lungs and their Ve$$els, as to ob$truct
the Circulation of the Blood. And this
<pb n=343>
Conjecture, as it is $pecious enough, $o I
might have admitted it for true; but that
I con$ider'd, that (not to mention that
one, e$pecially of the Animals kill'd in
our Engine, $eem'd manife$tly for a pret-
ty while, and not long before he dy'd, to
move his <I>Thorax,</I> as if he exerci$'d Re$pi-
ration) the diligent <I>Wall&aelig;us</I> relates, That
he divers times ob$erv'd, in the Di$$ecti-
on of live Bodies, that the Membrane
that inve$ts the Lungs, had Pores in it
as big as the larger $ort of Peas, which a-
grees with the Ob$ervations of Chyrur-
gions and Phy$itians, <I>viz.</I> That matter
collected in the <I>Thorax,</I> has penetrated in-
to the Lungs, and been di$charged by
coughing. And I remember too, that mo$t
of the Animals we kill'd in our Engine
were Birds, of who$e Lungs <I>Harvey</I>
$omewhere informs us, That he ob-
$erv'd them very manife$tly to open at
their Extremities into the <I>Abdomen.</I>
And by $uch Perforations we may well
$uppo$e the pa$$age free betwixt the exter-
nal Air and that in the <I>Abdomen:</I> But this
Conjecture may be further con$ider'd.
Be$ides, to $how that the Animals that
died in our Gla$$es, need not be $uppo$'d
<pb n=344>
to have been kill'd by the want of Air, we
fore$ee another Argument that we mu$t
deal $o ingeniou$ly with Your Lord$hip,
as not to conceal. You very well know,
that be$ides the generality of the
Schools, there are many new Philo$ophers
who, though they di$$ent from the old
Peripateticks in other things, do, as they,
deny the po$$ibility of a <I>Vacuum;</I> and
hold, that tho$e $paces which are devoid
of Air, and other gro$$er Bodies, are all
of them exactly repleni$hed with a certain
Etherial Matter, $o thin and $ubtle, that
it can freely permeate the Pores of the
compacted$t and clo$e$t Bodies, and ev'n
of Gla$s it $elf. Now $ome of tho$e Na-
turali$ts that are of this per$wa$ion may
object, That the Animals that died in our
Receivers, did $o, not $o much for lack of
Air, as by rea$on that the Air that was
pump'd out was nece$$arily $ucceeded by
an Etherial Sub$tance; which con$i$ting of
parts vehemently agitated, and $o very
$mall, as without re$i$tance to pa$s in and
out through the very Pores of Gla$s; it
may well be $uppo$'d, that a con$iderable
quantity of this re$tle$s and $ubtle Mat-
ter, meeting together in the Receiver,
<pb n=345>
with the exce$$ive heat of it, may be
quickly able to de$troy a little Animal, or
at lea$t, make the Air too intemperately
hot to be fit for Re$piration.
<p>But though this be a Difficulty not $o
ea$ily to be re$olv'd without the a$$i$tance
of our Engine, yet I $uppo$e we have al-
ready an$wer'd the Objection by our 38<SUP>th</SUP>
and 39<SUP>th</SUP> Experiments; which though we
made partly for other purpo$es, yet we
premi$'d them onely to clear up the diffi-
culty propo$'d.
<p>Another $u$pition we $hould have en-
tertain'd concerning the death of our Ani-
mals, namely, That upon the $udden re-
moval of the wonted pre$$ure of the am-
bient Air, the warm Blood of tho$e Ani-
mals was brought to an Efferve$cence or
Ebullition, or at lea$t $o vehemently ex-
panded, as to di$turb the Circulation of
the Blood, and $o di$order the whole Oe-
conomy of the Body. (This (I $ay) I
$hould have had $ome $u$pition of) but
that Animals of a hot Con$titution are
not the $ole ones that cannot in our ex-
hau$ted Engine exerci$e the Function of
Life. But I mu$t not now dwell upon
matters of this nature, becau$e I think
it high time to proceed to the con$iderati-
<pb n=346>
on of the principal $ubject of our Engine,
namely, The u$e of Re$piration; or ra-
ther, The u$e of the Air in Re$piration.
For whereas of the divers u$es of it men-
tion'd by Anatomi$ts the mo$t, $uch as
the Production and Modulation of the
Voice by the Eli$ion of the Air, the <I>La-
rynx</I> &amp;c. the expul$ion of Excrements
by Coughing, the conveying in of Odours
by In$piration, and $ome others, rather
convenient for the well being of an Ani-
mal, then ab$olutely nece$$ary to his Life:
Whereas (I $ay) the other u$es are $uch as
we have $aid, The great <I>Hippocrates</I> him-
$elf gives this notable Te$timony to the
u$e of the Air, as to Animals endow'd
with Lungs, <I>Mortalibus</I> ($ays he) <I>hic</I> ($pi-
ritus) <I>tum vit&aelig;, tum morborum &aelig;grotis cau-
$a e$t. Tant&aacute;que corporibus omnibus $pi-
rit&ucirc;s ine$t nece&szlig;itas, ut $iquidem aliis om-
nibus &amp; cibis &amp; potionibus, quis <*>b$tineat,
duos tam&etilde; aut tres, vel plures dies po&szlig;it vi-
tam ducere: At $i quis $piritus in corpus
vias intercipiat, vel exigu&acirc; diei parte, he-
mini pereundum $it; Adeo nece$$arius e$t
u$us $pirit&ucirc;s in corpore. Ad h&aelig;c quo&queacute;,
quum omnibus aliis actionibus homines qui-
e$cant, quod mutationibus innumer is vita
$it expo$ita, ab h&acirc;c tamen $ol&acirc; actione nun-</I>
<pb n=347>
<I>quam de$i$tant animantia, quin aut $piritum
adducant, aut reddant.</I>
<p>But touching the account upon which
the In$piration and Ex$piration of Air
(both which are comprehended in <G>a)gapno<*></G>,
Re$piration) is $o nece$$ary to Life, both
Naturali$ts and Phy$itians do $o di$agree,
that it will be very difficult either to re-
concile their Opinions, or determine their
Controver$ies.
<p>For fir$t, Many there are who think
the chief (if not $ole) u$e of Re$piration
to be the Cooling and tempering of that
Heat in the Heart and Blood, which other-
wi$e would be immoderate: And this O-
pinion, not onely $eems to be mo$t recei-
ved among$t Schola$tick Writers, but di-
vers of the new Philo$ophers, Carte$ians,
and others, admitted with $ome variation;
teaching, That the Air is nece$$ary, by its
coldne$s, to conden$e the Blood that pa$-
$es out of the right Ventricle of the
Heart into the Lungs, that thereby it may
obtain $uch a con$i$tence, as is requi$ite
to make it fit Fewel for the vital Fire or
Flame, in the left Ventricle of the heart.
And this Opinion $eems favor'd by this,
That Fi$hes, and other cold Creatures,
who$e Hearts have but one cavity, are al-
<pb n=348>
$o unprovided of Lungs, and by $ome o-
ther con$iderations. But though it need
not be deny'd, that the in$pir'd Air may
$ometimes be of u$e by refrigerating the
Heart; yet (again$t the Opinion that makes
this Refrigeration, the mo$t genuine and
con$tant u$e of the Air) it may be Obje-
cted, That divers cold Creatures ($ome
of which, as particularly Frogs, live in
the Water) have yet need of Re$piration,
which $eems not likely to be needed for
Refrigeration by them that are de$titute of
any $en$ible heat, and be$ides, live in the
cold Water: That even decrepid old
Men, who$e natural heat is made very
languid, and almo$t extingui$h'd by rea-
$on of age, have yet a nece$$ity of fre-
quent Re$piration: That a temperate Air
is fitte$t for the generality of breathing
Creatures; and as an Air too hot, $o al-
$o an Air too cold, may be inconvenient
for them (e$pecially, if they be troubled
with an immoderate degree of the $ame
Quality which is predominant in the Air:)
That in $ome Di$ea$es the natural heat is
$o weaken'd, that in ca$e the u$e of Re$pi-
ration were to cool, it would be more
hurtful then beneficial to breath; and the
$u$pending of the Re$piration, may $up-
<pb n=349>
ply the place of tho$e very hot Medicines
that are wont to be employ'd in $uch Di-
$tempers: That Nature might much bet-
ter have given the Heart but a moderate
heat, then $uch an exce$$ive one, as needs
to be perpetually cool'd, to keep it from
growing de$tructive; which the gentle,
and not the burning heat of an Animals
Heart, $eems not inten$e enough $o indi-
$pen$ably to require. The$e, and other
Objections, might be oppo$'d, and pre$$'d
again$t the recited Opinion: But we $hall
not in$i$t on them, but onely adde to
them, That it appears not by our fore-
going Experiments (I mean the 38<SUP>th</SUP> and
39<SUP>th</SUP>) that in our exhau$ted Receiver,
where yet Animals die $o $uddenly for
want of Re$piration, the ambient Body is
$en$ibly hotter then the common Air.
<p>Other Learned Men there are, who will
have the very $ub$tance of the Air to get
in by the Ve$$els of the Lungs, to the
left Ventricle of the Heart, not onely to
temper its heat, but to provide for the
generation of Spirits. And the$e alledge
for them$elves the Authority of the An-
tients, among whom <I>Hippocrates</I> $eems
manife$tly to favor their Opinion; and
both <I>Ari$totle</I> and <I>Galen</I> do $ometimes
<pb n=350>
(for methinks they $peak doubtfully e-
nough) appear inclinable to it. But for
ought ever I could $ee in Di$$ections, it is
very difficult to make out, how the Air is
convey'd into the left Ventricle of the
Heart, e$pecially the <I>Sy$tole</I> and <I>Dia$tole</I>
of the Heart and Lungs, being very far
from being Synchronical: Be$ides, that
the Spirits $eeming to be but the mo$t
$ubtle and unctuous Particles of the
Blood, appear to be of a very differing
Nature from that of the lean and incom-
bu$tible Corpu$cles of Air. Other Ob-
jections again$t this Opinion have been
propo$'d, and pre$t by that excellent Ana-
tomi$t, and my Indu$trious Friend, Dr.
<I>Highmore,</I> to whom I $hall therefore refer
you.
<p>Another Opinion there is touching Re-
$piration, which makes the genuine u$e of
it to be Ventilation (not of the Heart,
but) of the Blood, in its pa$$age thorow
the Lungs; in which pa$$age, it is di$-
burthened of tho$e Excrementitious
Steams, proceeding, for the mo$t part,
from the $uperfluous Sero$ities of the
Blood, (we may adde) and of the <I>Chyle</I>
too, which (by tho$e new Conduits of
late very happily detected by the famous
<pb n=351>
<I>Pecquet</I>) hath been newly mix'd with it in
the Heart.) And this Opinion is that of
the Indu$trious <I>M&oelig;bius,</I> and is $aid to
have been that of that excellent Philo$o-
pher <I>Ga$$endus;</I> and hath been in part an
Opinion almo$t vulgar: But this <I>Hypo-
the$is</I> may be explicated two ways: For
fir$t, The nece$$ity of the Air in Re$pi-
ration, may be $uppo$'d to proceed from
hence; That as a Flame cannot long burn
in a narrow and clo$e place, becau$e the
Fuliginous Steams it unce$$antly throws
out, cannot be long receiv'd into the am-
bient Body; which after a while growing
too full of them, to admit any more, $ti-
fles the flame, $o that the vital Fire in the
Heart requires an ambient Body, of a
yielding nature, to receive into it the $u-
perfluous Sero$ities and other Recrements
of the Blood, who$e $ea$onable Expul$i-
on is requi$ite to depurate the Ma$s of
Blood, and make it fit both to Circulate;
and to maintain the vital heat re$iding in
the Heart. The other way of explicating
the above-mention'd <I>Hypothe$is,</I> is, by
$uppo$ing, that the Air does not onely, as
a Receptacle, admit into its Pores the Ex-
crementitious vapors of the Blood, when
they are expell'd through the Wind-Pipe,
<pb n=352>
but does al$o convey them out of the
Lungs, in regard that the in$pired Air,
reaching to all the ends of the <I>A$pera Ar-
teria,</I> does there a$$ociate it $elf with the
Exhalations of the circulating Blood, and
when tis exploded, carrys them away with
it $elf, as we $ee that winds $peedily dry up
the $urfaces of wet Bodies, not to $ay any
thing of what we formerly ob$ervd touch-
ing our Liquor, who$e fumes were $trange-
ly elevated upon the Ingre$s of the Air.
<p>Now of the$e two ways of explicating
the u$e of Re$piration, our Engine af-
fords us this Objection again$t the fir$t;
That upon the Ex$uction of the Air, the
Animals die a great deal $ooner then if it
were left in the Ve$$el; though by that
Ex$uction the ambient $pace is left much
more free to receive the $teams that are ei-
ther breathed out of the Lungs of the
Animal, or di$charg'd by in$en$ible Tran-
$piration through the Pores of his
Skin.
<p>But if the <I>Hypothe$is</I> propo$'d, be taken
in the other $en$e, it $eems congruous e-
nough to that grand ob$ervation, which
partly the <I>Ph&aelig;nomena</I> of our Engine, and
partly the relations of Travellers, have
$ugge$ted to us, namely, That there is a
<pb n=353>
certain con$i$tence of Air requi$ite to Re-
$piration; $o that if it be too thick, and
already over-charged with vapors, it will
be unfit to unite with, and carry off tho$e
of the Blood, as Water will di$$olve, and
a$$ociate to it $elf but a certain proportion
of $aline Corpu$cles; and if it be too
thin or rarefied, the number or $ize of the
A&euml;rial Particles is too $mall to be able to
a$$ume and carry off the halituous Excre-
ments of the Blood, in $uch plenty as is
requi$ite.
<p>Now that Air too much thicken'd (and
as it were clogg'd) with Steams, is unfit
for Re$piration, may appear by what is
wont to happen in the Lead-Mines of <I>De-
von$hire,</I> (and, for ought I know, in tho$e
too of other Countrys, though I have
$een Mines where no $uch thing was com-
plain'd of) for I have been inform'd by
more then one credible Per$on (and parti-
cularly by an Ingenious Man, that has of-
ten, for curio$ity, digg'd in tho$e Mines,
and been imploy'd about them) that there
often ri$es Damps, as retaining the <I>Ger-
mane</I> Word by which they call them)
which does $o thicken the Air, that unle$s
the Work-men $peedily make $igns to
them that are above, they would (which
<pb n=354>
al$o $ometimes happens) be pre$ently
$tifled for want of Breath; and though
their Companions do make ha$te to draw
them up, yet frequently, by that time
they come to the free Air, they are, as it
were, in a $woon, and are a good while be-
fore they come to them$elves again. And
that this $wooning $eems not to proceed
from any Ar$enical or Poy$onous Exhala-
tion contain'd in the Damp, as from its
over-much conden$ing the Air, $eems pro-
bable from hence; That the $ame Damps
oftentimes lei$urely extingui$h the flames
of their Candles or Lamps; and from
hence al$o that it appears (by many Rela-
tions of Authentical Authors) that in
tho$e Cellars where great $tore of new
Wine is $et to work, men have been $uffo-
cated by the too great plenty of the $teams
exhaling from the Mu$t, and too much
thickning the Air: as may be gathered
from the cu$tom that is now u$ed in $ome
hot Countrys, where tho$e that have oc-
ca$ion to go into $uch Cellars, carry with
them a quantity of well kindled Coals,
which they hold near their Faces; where-
by it comes to pa$s, that the Fire di$cu$-
$ing the Fumes, and rarefying the Air re-
duces the ambient Body to a con$i$tence fit
for Re$piration.