Boyle, Robert, New experiments physico-mechanicall, touching the spring of the air and its effects, 1660

Bibliographic information

Author: Boyle, Robert
Title: New experiments physico-mechanicall, touching the spring of the air and its effects
Date: 1660

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Document ID: MPIWG:SUV5ZB7D
Permanent URL: http://echo.mpiwg-berlin.mpg.de/MPIWG:SUV5ZB7D

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Copyright: Max Planck Institute for the History of Science (unless stated otherwise)
License: CC-BY-SA (unless stated otherwise)
1
NEW
EXPERIMENTS
Phyſico-Mechanicall

Touching
the Air.
1
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1
NEW
EXPERIMENTS

Phyſico-Mechanicall,
Touching
The SPRING of the AIR,
and
its EFFECTS,
(Made, for the moſt part, in a New
PNEuMATICAL ENGINE)
Written by way of LETTER
To the Right Honorable Charles
Lord
Vicount of Dungarvan,
Eldeſt
Son to the EARL of CORKE.
By the Honorable Robert Boyle Eſque
1[Figure 1]
OXFORD:
Printed
by H: Hall, Printer to the Univerſity,
for
The: Robinſon. 1660.
1
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12[Figure 2]
To the Reader.
ALthough the following Trea­
tiſe
being far more prolix
then
becomes a Letter, and
then
I at firſt intended it; I
am
very unwilling to en­
creaſe
the already exceſsive bulk of the
Book
by a Preface, yet there are ſome par­
ticulars
that I think my ſelf oblig'd to take
notice
of to the Reader, as things, that will
either
concern him to know, or me to have
known
.
In the firſt place then: If it be demand­
ed
why I publiſh to the World a Letter, which
by
its Stile and diverſe Paſſages, appears
to
have been written as well For, as To a
particular
Perſon; I have chiefly theſe two
things
to anſwer: The one, That the Ex­
periments
therein related, having been ma­
ny
of them try'd in the preſence of Ingeni­
ous
Men; and by that means having made
1ſome noiſe among the Virtuoſi (inſomuch
that
ſome of them have been ſent into Fo­
reign
Countries, where they have had the
luck
not to be deſpiſ'd) I could not without
quite
tyring more then one Amanuenſis, give
out
half as many Copies of them as were ſo
earneſtly
deſired, that I could not civilly
refuſe
them.
The other, That intelligent
Perſons
in matters of this kinde perſwaded
me
, that the publication of what I had ob­
ſerv
'd touching the Nature of the Air,
would
not be uſeleſs to the World; and that
in
an Age ſo taken with Novelties as is ours,
theſe
new Experiments would be grateful to
the
Lovers of free and real Learning: So
that
I might at once comply with my grand
Deſign
of promoting Experimental and
Uſeful
Philoſophy, and obtain the great ſa­
tisfaction
of giving ſome to ingenious Men;
the
hope of which, is, I confeſs, a tempta­
tion
that I cannot caſily reſiſt.
Of my being ſomewhat prolix in many
of
my Experiments, I have theſe Reaſons
to
render, That ſome of them being altoge­
ther
new, ſeem'd to need the being circum­
ſtantially
related, to keep the Reader from
diſtruſting
them: That divers Circum­
ſtances
I did here and there ſet down for fear
of
forgetting them, when I may hereafter
1have occaſion to make uſe of them in my
ther
Writings: That in divers caſes I
thought
it neceſſary to deliver things cir­
cumſtantially
, that the Perſon I addreſſed
them
to, might without miſtake, and with
as
little trouble as is poſsible, be able to re­
peat
ſuch unuſual Experiments: and that
after
I conſented to let my Obſervations be
made
publick, the moſt ordinary Reaſon of
my
prolixity was, That foreſeeing that ſuch
a
trouble as I met with in making thoſe try­
als
carefully, and the great expence of time
that
they neceſſarily require, (not to mention
the
charges of making the Engine, and im­
ploying
a man to manage it) will probably
keep
moſt men from trying again theſe Ex­
periments
; I thought I might doe the gene­
rality
of my Readers no unacceptable pece
of
ſervice, by ſo punctually relating what
I
carefully obſerv'd, that they may look up­
on
theſe Narratives as ſtanding Records in
our
new Pneumaticks, and need not reite­
rate
themſelves an Experiment to have as
diſtinct
an Idea of it, as may ſuffice them
to
ground their Reflections and Speculations
upon
.
And becauſe ſometimes 'tis the Diſcourſe
made
upon the Experiment that makes it
appear
prolix, I have commonly left a con-
1ſpicuous interval betwixt ſuch Diſcourſes,
and
the Experiments whereunto they belong,
or
are annexed; that they who deſire onely
the
Hiſtorical 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 ſake of thoſe
that
are well verſ'd in the New Philoſophy,
and
in the Mathematicks; that ſuch
may
skip what was deſign'd, but for ſuch
Perſons
as may be leſs acquainted even then
I
, with matters of this nature (ſcarce ſo
much
as mention'd by any Writer in our
Language
) and not for them from whom
I
ſhall be much more forward to learn, then
to
pretend to teach them.
Of my being
wont
to ſpeak rather doubtfully, or heſitant­
ly
, then reſolvedly, concerning matters
wherein
I apprehend ſome difficulty, I have
in
another Treatiſe (which may, through
Gods
Aſsiſtance, come abroad ere long)
given
a particular, and I hope a ſatisfacto­
ry
account: Wherefore I ſhall now defend
my
Practice but by the Obſervation of Ari­
ſtotle
, who ſomewhere notes, That to ſeem
to
know all things certainly, and to ſpeak
poſitively
of them, is a trick of bold and
yong
Fellows: Whereas thoſe that are in-
1deed intelligent and conſiderate, are wont to
imploy
more wary and diffident Expreſsi­
ons
, or (as he ſpeaks) σιφέαδ ἀεὶ τὸ ς,
τὸ τὰχα.
There are divers Reflections, and other
Paſſages
in the following Epiſtle, and even
ſome
Experiments (occaſionally mention'd)
which
may ſeem either impertinent or ſu­
perfluous
, but are not ſo: Being purpoſely
written
, either to evince ſome truth oppoſ'd,
or
diſprove ſome erroneous conceit main­
tain
'd, by ſome eminent New Philoſopher,
or
by ſome other Ingenious Men, who, I
preſum
'd, would eaſily forgive me the ha­
ving
on ſuch occaſions purpoſely omitted
their
Names; though an inquiſitive Perſon
will
probably diſcover divers of them, by
the
mention of the Opinions diſprov'd in
the
Experiments I am excuſing.
Ever ſince I diſcern'd the uſefulneſs
of
ſpeculative Geometry to Natural Phi­
loſophy
, the unhappy Diſtempers of my Eyes,
have
ſo far kept me from being much con­
verſant
in it, that I fear I ſhall need the par­
doz
of my Mathematical Readers, for ſome
Paſſages
, which if I had been deeply skill'd
in
Geometry, I ſhould have treated more ac­
curately
.
1
And indeed, having, for Reaſons elſe­
where
deduc'd, purpoſely kept my ſelf a
ſtranger
to moſt of the new Hypotheſes in
Philoſophy
, I am ſenſible enough that the
Engine
I treat of has prevail'd with me to
write
of ſome ſubjects which are ſufficient­
ly
remote from thoſe I have been moſt con­
verſant
in.
And having been reduc'd to
write
the greateſt part of the enſuing Letter
at
a diſtance, not onely from my Library,
but
from my own Manuſcripts, I cannot
but
fear that my Diſcourſes do not onely
want
many choice things wherewith the
Learned
Writings of others might have en­
riched
or imbelliſhed them: But that partly
for
this Reaſon, and partly for that touch'd
upon
a little before, It is poſsible I may
have
mention'd ſome Notions already pub­
liſh
'd by others, without taking notice of the
Authors
, not out of any deſign to defraud
deſerving
Men, but for want of knowing
ſuch
particulars to have been already pub­
liſh
'd by them: Eſpecially the Experiments
of
our Engine being themſelves ſufficient
to
hint ſuch Notions as we build upon
them
.
The order of the Experiments every
Reader
may alter, as ſuits beſt with his own
Deſign
in peruſing them; For not onely all
1thoſe betwixt whom there is an Affinity in
Nature
(by belonging to one ſubject) are not
always
plac'd one by another, but they are
not
ſtill ſet down ſo much as in the order
wherein
they were made; but moſt common­
ly
in that caſual one wherein my occaſions in­
duc
'd me to diſpatch them to the Preſs.
And,
which
is worſe, I did uſually ſend quite
way
the former Experiments, before the
later
were written, or perhaps ſo much as
made
: Whereby I loſt the advantage of cor­
recting
and ſupplying the Imperfections of
what
I had formerly written, by the light of
my
ſubſequent Tryals and Diſcoveries.
Beſides all this, the diſtemper in my eyes
forbidding
me not onely to write my ſelf ſo
much
as one Experiment, but even to read
over
my ſelf what I dictated to others.
I can­
not
but fear, that beſides the Authors miſtakes,
this
Edition may be blemiſh'd by many, that
may
be properly imputed to a very unskil­
ful
Writer (whom I was often times by haſte
reduc
'd againſt my cuſtom to imploy) and
may
have eſcaped the Diligence of that
Learned
Friend, that does me the favor to
over-ſee
the Preſs; eſpecially there being
the
diſtance of two days Fourney betwixt it
and
me.
I need not perhaps repreſent to the equi-
1table Reader, how much the ſtrange Confu­
ſions
of this unhappy Nation, in the midſt
of
which I have made and written theſe
Experiments
, are apt to diſturb that calm­
neſs
of Minde, and undiſtractedncſs of
Thoughts
, that are wont to be requiſite to
Happy
Speculations.
But I preſume,
that
by all theſe things put together, he
will
readily perceive, That I have been
ſo
far from following the Poets prudent
Counſel
touching the ſlow Publication of
Books
deſign'd to purchaſe credit by,
—— Nonumque prematur in Annum
that I ſuffer this Treatiſe to come abroad
into
the World with a multitude of Diſad­
vantages
.
But if it be demanded, why then I did
not
make it fitter for the Preſs before I ſent
it
thither?
my Anſwer muſt be, That not
at
firſt imagining that this ſort of Experi­
ments
would prove any thing near ſo trouble­
ſome
, either to make, or to Record, as I
afterwards
found them, I did, to engage
the
Printer to diſpatch, promiſe him to ſend
him
the whole Epiſtle in a very ſhort time:
So
that although now and then the occaſional
vacations
of the Preſs, by reaſon of Feſti-
1vals, or the abſence of the Corrector, gave
me
the leiſure to exſpaciate upon ſome ſub­
ject
; yet being oftentimes call'd upon to diſ­
patch
the Papers to the Preſs, my promiſe,
and
many unexpected Avocations, obliged
me
to a haſte, which, though it have detract­
ed
nothing from the Faithfulneſs of the
Hiſtorical
part of our Book, has (I fear)
been
diſadvantageous enough to all the reſt.
And I made the leſs ſcruple to let the fol­
lowing
Papers paſs out of my hands, with
all
their Imperfections; becauſe, as the
publick
Affairs, and my own, were then
circumſtanc
'd, I knew not when (if at all)
I
ſhould be again in a condition to proſecute
Experiments
of this kinde; eſpecially,
ſince
(to omit my being almoſt weary of be­
ing
, as it were, confin'd to one ſort of Ex­
periments
) I am pre-ingag'd (if it pleaſe
God
to vouchſafe me Life and Health) to
imploy
my firſt leiſure in the publication of
ſome
other Phyſiological Papers, which I
thought
'twould make me much the ſitter to
take
in hand, if I firſt diſpatch'd all that
I
had at this time to write touching our
Engine
.
I have this further to adde, by way
of
Excuſe, That as it has been my deſign
in
publiſhing theſe Experiments to gratifie
1Ingenious men; ſo, 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 leaſt) ſomewhat awaken
mens
thoughts, & excite them to new ſpecula­
tions
(ſuch as perhaps even inquiſitive men
would
ſcarce elſe light upon) and I need not
deſpair
, that even the examination of ſuch
new
Suſpicions and Enquiries will hence al­
ſo
, at leaſt Occaſionally be facilitated: I
ſaid
Occaſionally, becauſe it being, as 'tis
proverbially
ſaid, Facile Inventis addere.
It ſeems not irrational to expect, that our
Engine
it ſelf, and divers of our Experi­
ments
, will be much promoted by the Indu­
ſtry
of Inventive and Mathematical Wits,
whoſe
contrivances may eaſily either correct
or
ſupply, and conſequently ſurpaſs many of
thoſe
we have made uſe of.
And, particu­
larly
, if Men by skill and patience can ar­
rive
both to evacuate ſuch Receivers as
ours
, till there be no more Air left in them,
then
there ſeems to have remain'd in the
Glaſſes
made uſe of about the Magdebur­
gick
Experiment (hereafter to be mention­
ed
) and to keep out the Air for a competent
while
, the Uſefulneſs and Diſcoveries of our
Engine
, will not be a little advanc'd.
And
perhaps
that may belong to it, which I re-
1member Seneca ſpeaks of Nature, Initia­
tos
(ſays be) nos credimus, in Veſtibulo
ejus
hæremus: For being now in a place
where
we are not quite deſtitute of moderate­
ly
skilful Artificers, we have, ſince the
Concluſion
of the following Letter, made
ſome
Additions to our Engine, by whoſe help
we
finde (upon ſome new tryals) that we
may
be able, without much of new trouble,
to
keep the ambient Air out of the exhau­
ſted
Receiver for a whole day; and perhaps
we
ſhould be able to keep it out much longer,
if
before we ſhall have diſpatch'd ſome ur­
gent
Affairs, and publiſh'd ſome Papers for
which
a kinde of Promiſe is thought to make
us
Debtors to the Preſs, we could be at lei­
ſure
to proſecute ſuch Experiments, as may
poſsibly
afford a Supplement to the follow­
ing
Treatiſe, from which I ſhall now no lon­
ger
detain the Reader.
I know
1
[Empty page]
13[Figure 3]
Friendly Reader,
I Know all Perſons
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 Uſe,
then
this you ſee it now attir'd
in
; eſpecially ſince the Excel­
lent
Noble Perſon, who is the
Author
, is known to be well
ble
himſelf (being almoſt uni­
verſally
a Linguiſt) to have gi­
ven
it either the Old Latin, or
1the newer French Dreſs.
But if it be an Honor to a
Language
to be preferr'd, and
this
Honor breeds ſometimes an
Emulation
, as anciently it did
between
the Greeks and Ro­
mans
, it cannot be thought
unhandſome
for an Engliſh
Nobleman
to have preferr'd
his
own: And it may be a ſuf­
ficient
Reaſon for the Gentry
of
Forein Parts to learn our
Speech
, or keep Interpreters,
that
they are ſure to have for
their
requital, from many of
our
Engliſh Writers (as here
from
this piece) much curiouſly
ingenious
, and profitable Lear­
ning
.
1
But as to this particular (give
me
leave to uſe Words from a
Story
) Since the Mountain
cannot
come to Mahomet,
Mahomet
will go to the
Mountain
: I mean thus;
Becauſe
many witty Men, Per­
ſons
of Honor and Eſtate eſpe­
cially
, may be ſuppoſ'd to be
ble
to make a better account, by
employing
their Studies and
Time
on Matter then Words,
and
ſo are juſtly impeded from
learning
Languages; And be­
cauſe
(as I may judge) the no­
ble
Author is willing to oblige all
Men
, He has already provi­
ded
, that this piece ſhall ſhort­
ly
be done into Latine, that ſo
1it may come home to divers wor­
thy
Perſons in its Stream, who
cannot
travel to finde it out in
its
firſt Origine.
Having therefore leave ſo
to
do, I cannot forbear to give
the
World the Advertiſement
of
this Latine Edition, leſt
ſome
skilful Artiſt ſhould take
needleſs
pains about a Work,
which
will, ere long (by Gods
furtherance
) be done to his
Hands
; For ſuch unprofitable
expences
of Study have too fre­
quently
happened, and too much
to
the diſadvantage of Learn­
ing
, for want of a ſufficient
Correſpondence
and Intercourſe
between
ſuch as are exerciſed
1in the Mines of Wiſdome.
This is all the trouble I ſhall
at
preſent give you: Nor ſhall I
need
minde thee, if you have a
true
guſt for the Book you read,
to
have an honor and thankful
regard
to the Perſon that has
favor
'd us with the Communi­
cation
of theſe his Tryals, & is
manifeſtly
ſo great a Patron
and
Friend to Experimental
Learning
, and all true Wiſdom;
for
ſhould you fail in this, you
might
deſervedly be depriv'd of
ſome
other Obſervations on the
ſame
ſubject, which the Au­
thor
, I heare, has made ſince the
finiſhing
of this Treatiſe.
I deſire to be excuſed that I
1not make Excuſes for the ſlow­
neſs
of the Publication, hoping
that
the long expectation you
have
had of it, will enhance, and
not
diminiſh your delight in the
enjoyment
of a piece like to be,
amongſt
the ſtudents in accurate
Philoſophy
, of ſo generall accep­
tance
.
Farewel.
R: Sh.
4[Figure 4]
15[Figure 5]
A Summary of the chief Matters treated
of
in this Epiſtolical Diſcourſe.
THe Proæmium, wherein is ſet down the
occaſion
of this Diſcourſe, 1. The mo­
tives
that induc'd the Author thereunto, 2 &c.
The hints he received, 5. The things where­
in
this Engine excels any that have yet been
made
uſe of, 6 &c. The deſcription of the
Engine
and its parts, 8 &c. The way of pre­
paring
and uſing it, 15 &c. The diviſion of
the
Experiments tryable thereby into two
ſorts
, and the difficulty of excluding the
Air
. 18 &c.
The firſt Experiment, touching the man­
ner
of pumping out the Air, and by what de­
grees
the Receiver is emptyed, 20, &c. A di­
greſsion
touching the Spring or Elaſtical
power
of the Air, with an attempt for a Me­
chanical
Explication thereof, neceſſary to be
premiſ
'd for the explanation of the Phæno­
mena
, exhibited in this and the ſubſequent
Experiments
. 22 &c.
The ſecond Experiment, touching the preſ­
ſure
of the Air againſt the ſides of the Bodies
it
invirons, 37 &c. with a digreſsive Ex­
plication
of the preſſure of the Air included
within
an ambient Body. 39 &c.
1
The third Experiment, touching the
force
requiſite to draw down the Sucker, 42
&c. The Opinion of an eminent Modern
Naturaliſt
examin'd. 44 &c.
The fourth Experiment, touching the
ſwelling
of a Bladder; with the degrees by
which
it increaſes, 45 &c. Another Opini­
on
of a Learned Author examin'd. 48 &c.
The fifth Experiment, touching the break­
ing
of a Bladder in the Receiver, 49 &c.
And of another by heat. 52
The ſixth Experiment, of divers ways by
which
the elaſtical expanſion of the Air
was
meaſur'd. 52 &c
The ſeventh Experiment, touching what
Figure
does beſt reſiſt the preſſure of the Air. 62 &c.
The eighth Experiment, tending to a fur­
ther
Demonſtration of the former, from the
breaking
of glaſs a Helmet inward. 64 &c.
The ninth Experiment, contains a fur­
ther
confirmation from the breaking of a
Glaſs
outward, 66 &c. with an Experiment to
prove
, that theſe Phænomena proceed not
from
an invincible Fuga vacui 69. A de­
ſcription
of other ſmall Receivers, and their
Conveniencies
, 70 &c. A Receipt for the
making
of a Compoſition to Cement crackt
Glaſſes
. 73
1
The tenth Experiment, touching the fla­
ming
of Candles incloſed in the Receiver. 74 &c.
The eleventh Expertment, touching the
burning
of Coals, 78. And the laſting of
the
excandeſcence of an included piece of
ron
. 80.
The twelfth Experiment concerning the
burning
of Match. 82
The thirteenth Experiment, concerning
the
further proſecution of the preceding,
tending
to prove the extinction of the Fire
in
the former Experiments, not to have
proceeded
from the preſſure of the Fire by the
Fumes
, 84. Some remarkable Circumſtan­
ces
of it, 86. The Experiment of Match
try
'd in a ſmall Receiver. 87
The fourteenth Experiment, touching the
ſtriking
Fire, and kindling of Powder with
the
Lock of a Piſtol in the evacuated Recei­
ver
. 88 &c.
The fifteenth Experiment, touching the
unſucceſsfulneſs
of kindling included Bo­
dies
with a burning Glaſs, and the Au­
thors
intention to proſecute it further. 102
The ſixteenth Experiment, concerning the
operation
of the Loadſtone. 105, &c.
1
The ſeventeenth Experiment, touching the
gradual
deſcent of the Quick-ſilver in the
Torricellian
Experiment, 106 &c. Some
obſervable
Circumſtances concerning it,
112
&c. The ſame Experiment try'd in
one
of the ſmall Receivers, 115. How
this
Experiment may be made uſe of to know
the
ſtrength of the preſſure of the Air for
every
degree of Rarefaction, 116 &c. The
tryal
of the ſame Experiment in a Tube not
two
foot long, 118. The raiſing of the Mer­
curial
Cylinder, by the forcing of more Air
into
the Receiver, 119. Some Allegations
for
and againſt a Vacuum conſider'd, 120
&c. Some Advertiſements concerning the
inconveniencies
that may ariſe from the di­
verſity
of meaſures made uſe 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
ſurface of the Tube, 123 &c. Some
Expedients
for the more exact filling the
Tube
, 127. The height the Author once found
of
the Mercurial Cylinder, according to En­
gliſh
meaſure. 128.
The eighteenth Experiment, containing
a
new Obſervation touching the variation
of
the height of the Mercurial Cylinder in
the
ſame Tube, with an oſſer at the reaſon
1thereof. 129 &c.
The 19th Experiment, touching the ſub­
ſiding
of a Cylinder of Water, 140 &c. The
ſame
try'd in a ſmall Receiver. 143
The 20th Experiment, touching the Ela­
ter
of Water, with a digreſsive Experiment
to
the ſame purpoſe 144 &c.
The 21 Experiment, being a proſecution
of
the former Enquiry, by Experimenting
the
Generation of Bubbles under Water, a
recital
of ſome notable Circumſtances, with
ſome
obſervable Corollary's deduc'd there­
from
. 147 &c.
The 22d Experiment, tending to a deter­
mination
of the Enquiry propoſ'd in the for­
mer
Experiment, by proving the matter of
theſe
Bubbles from their permanency to be
Air
: The Experiments try'd in the great
and
ſmall Receivers, evincing the ſame
thing
, 155 &c. An Experiment wherein
there
appear'd Bubbles in Quick-ſilver,
160
. The Authors Inference, 162. A di­
greſsive
Enquiry, whether or no Air may be
generated
anew; with ſeveral Hiſtories and
Experiments
, tending to the reſolving and
clearing
thereof. 162 &c The Authors ex­
cuſe
for ſo long a Digreſsion. 181
The 23d Experiment, containing a fur­
ther
Enquiry touching Bubbles mad with
1common and diſtill'd Water. 182
The 24th Experiment, wherein the inqui­
ry
is proſecuted 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. 187 &c.
The wonderful expanſion of the Spirit of
Wine
. 194
The 25th Experiment, touching the ex­
panſion
and gravity of the Air under wa­
ter
. 195 &c.
The 26th Experiment, touching the Vi­
brations
of a Pendulum.
202 &c.
The 27th Experiment, touching the pro­
pagation
of ſound: And the Authors inten­
tion
of trying ſome other Experiments, for
the
further elucidation thereof. 210 &c.
The 28 Experiment, touching the ſudden
cruption
of Bubbles from the water, when
the
airs preſſure was ſpeedily remov'd. 214
The 29 Experiment, touching the cauſe
of
the aſcent of Fumes and Vapors, wherein
'tis prov'd (from the ſeveral motions, which
the
Fumes of a ſtrange ſmoaking Liquor, of
the
Authors, were obſerv'd to have in the Re­
ceiver
, upon the exſuction of the Air) that
the
reaſon of their aſcent proceeds from the
gravity
of the ambient air, and not from any
poſitive
levity of their own. 217 &c.
1
The 30 Experiment, concerning the na­
ture
of a fluid Body, illuſtrated by the exam­
ple
of ſmoak which in ſeveral circumſtances
ſeems
very much to reſemble the property of a
fluid
Body, 224 &c. A conjecture of the
cauſe
of the Suns undulation. 228
The 31 Experiment, concerning the Phæ­
nomena
of two flat Marbles exactly plain'd
and
wrought together, and the true reaſon
thereof
, 229. The Authors intention for the
further
proſecution thereof, & what hindred
him
; the reaſon 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 coheſion of flat Bodies. 231 &c.
The 32 Experiment, touching the forcible
preſſure
of the Air againſt the outward ſu­
perficies
of a Valve, faſten'd upon the ſtop­
cock
of the Receiver.
The Diameter of it,
and
the weight it ſuſtain'd. 233 &c.
The 33 experiment, touching the great preſ­
ſure
of the Air againſt the under ſuperficies
of
the Sucker, 236 &c. what weight was re­
quiſite
to depreſs it, & what weight it would
lift
and carry up with it, 239 &c. what im­
provement
& uſe there may be made of this
experiment
, 242. A Diſcourſe touching the
nature
of Suction, proving that fuga vacui
is not the adequate cauſe thereof. 243 &c.
1
The 34th Experiment, containing ſeveral
attempts
for the weighing of light Bodies in
the
exhauſted Receiver. 258 &c.
The 35th Experiment, touching the cauſe
of
Filtration, and the riſing of Water in
Siphons
, 262 &c. A relation of a new
kinde
of Siphon, of the Authors, upon
the
occaſion of trying the Experiment
lately
obſerv'd by ſome French-men, and fur­
ther
improv'd by himſelf; and ſome conje­
ctures
touching the cauſe of the exhibited
Phænomena
.
267 &c.
The 36th Experiment, touching the weigh­
ing
of a parcel of Air in the exhauſted Veſ­
ſel
; and ſome other Obſervations for the ex­
plication
thereof, 272 &c. An accidental
Experiment
, tending to the further confir­
mation
of the Authors Reflections upon the
firſt
Experiment; with a digreſsive Obſer­
vation
, noting the ſubtil penetrancy of ſome
Spirits
, to exceed by far that of the Air, 275
&c. And ſome other Experiments to ſhew the
difficulty
of the ingreſs of the Air into the
pores
or holes of ſome bodies into which Wa­
ter
will readily inſinuate it ſelf, 279 &c. with
a
conjecture at the cauſe thereof, 282. The
Author
returns to the proſecution if the in­
quiry
after the gravity of the Air: But firſt,
(upon the occaſion of the tenacity of a thin
1Bubble of Glaſs) ſets down his thoughts con­
cerning
the ſtrange exuperancy of ſtrength
in
Air, agitated by heat, above what the
ſame
has unagitated, 283 &c. And then pro­
ceeds
to the examination of the weight of the
Air
by an Æolipile, and compares the reſult
thereof
, with that of Merſennus, 286. The
Opinions
and Experiments of divers Au­
thors
, and ſome of his own, touching the
proportion
of weight betwixt Water and Air,
are
compar'd and examin'd by the Author,
288
. The reſult thereof, 290. Merſennus
his obſervation reconcil'd, with that of the
Author
; and the proportion between the gra­
vity
of Water and Air about London, 291
&c. After the recital of the Opinions of ſe­
veral
Writers, touching the proportion of
gravity
between Water and Quick-ſilver,
the
Author ſets down his own tryals, made
ſeveral
ways, together with his concluſion
therefrom
, 293 &c. The uſe he makes of this
inquiry
for the gheſsing at the height of the
Atmoſphere
, 297. What other Experiments
are
requiſite to the determination thereof.
299
&c.
The 37th Experiment, touching the ſtrange
and
odde Phænomenon, of the ſudden flaſh­
es
of light in the cavity of the Receiver; the
ſeveral
circumſtances and difficulties of it,
1with ſome attempts towards the rendering at reaſon
thereof
, 301, &c. The Difficulty of ſo doing fnr­
ther
ſhewn from the conſideration of the various
changes
of Air which doe not immediatly fall un­
der
our ſenſes, 315. this laſt propoſition prou'd
by
ſeverall obſervations. 316.
The 38. Experiment, touching the freezing of
water
, 319. &c. Aproblem, (concerning the great
force
wherewith a freezing Liquor extends its ſelfe,)
propoſ
'd upon the Conſideration of divers admirable
effects
wrought thereby. 320 &c.
The 39. Experiment, containing an inquiſition
after
the temperature of the ſubſtance that remain'd
in
the cavity of the Receiver, after the Air was well
exhauſted
.
The relation of a Phænomenon, ſeeming
to
proceed from the ſwelling of the Glaſs.
With an
advertiſement
concerning the pliableneſs of Glaſs in
ſmall
peices. 322. &c.
The 40. Experiment, touching the difficulty that
occur
'd in making tryall whether rarified Air
were
able to ſuſtaine flying inſects. 326. &c
The 41. Experiment, Exhibiting ſeverall try­
alls
touching the reſpiration of divers ſorts of ani­
malls
included in the Receiver, 328, &c. With a
digreſſion
containing ſome doubts touching reſpira­
tion
wherein are delivered ſeverall Experiments re­
lating
thereunto. 335 &c.
The 42. Experiment, touching the differing
peration
of corroſive Liquors in the emptied Receiver
and
in the open Air. 384
The 43. Experiment, touching the ſpontaneous
bullition
of warm Liquors in the exhauſted Receiver. 388
The Concluſion. 394
1
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110[Figure 10]
TO THE
LORD

OF

DUNGARVAN,
My
Honoured and Dear
NEPHEW
.
My Dear Lord,
REceiving in your laſt from
Paris, a deſire that I would
adde
ſome more Experi­
ments
to thoſe I formerly
ſent
You over: I could not
be
ſo much your Servant as I am, without
looking
upon that Deſire as a Com­
mand
; and conſequently, without think­
ing
my ſelf obliged to conſider by what
ſort
of Experiments it might the moſt ac­
ceptably
be obey'd.
And at the ſame
1time, perceiving by Letters from ſome
other
Ingenious Perſons at Paris, that ſe­
veral
of the Virtuoſi there, were very
intent
upon the examination of the Inte­
reſt
of the Ayr, in hindring the deſcent
of
the Quick-ſilver, in the famous Expe­
riment
touching a Vacuum: I thought I
could
not comply with your Deſires in a
more
fit and ſeaſonable manner, then by
proſecuting
and endeavoring to promote
that
noble Experiment of Torricellius:
and
by preſenting your Lordſhip an ac­
count
of my attempts to illuſtrate a ſub­
ject
, about which, it's being ſo much diſ­
courſ
'd of where you are, together with
your
inbred Curioſity, and love of Ex­
perimental
Learning, made me ſuppoſe
you
ſufficiently inquiſitive.
And though I pretend not to acquaint
you
, on this occaſion, with any ſtore of
new
Diſcoveries yet poſſibly I ſhall be ſo
happy
, as to aſſiſt you to know ſomethings
which
you did formerly but ſuppoſe; and
ſhall
preſent you, if not with new Theo­
ries
, at leaſt with new Proofs of ſuch as
are
not yet become unqueſtionable.
And
if
what I ſhall deliver, have the good for­
tune
to encourage and aſſiſt you to proſe­
cute
the Hints it will afford, I ſhall ac-
1count my ſelf, 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 Philoſophy,
the
effectual purſuit of which, requires
as
well a Purſe as a Brain, to endeere it
to
hopeful Perſons of your Quality: who
may
accompliſh many things which
thers
can but wiſh or, at moſt, but deſign,
by
being able to imploy the Preſents of
Fortune
in the ſearch of the Myſteries of
Nature
.
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 Lordſhip upon, by theſe two
Conſiderations
: The one, That the Ayr
being
ſo neceſſary to humane Life, that
not
onely the generality of Men, but
moſt
other Creatures that breath, can­
not
live many minutes without it; any
conſiderable
diſcovery of its Nature,
ſeems
likely to prove of moment to
Man-kinde
.
And the other is, That the
Ambient
Ayr, being that whereto both
our
own Bodies, and moſt of the others
we
deal with here below, are almoſt per­
petually
contiguous; not onely its alte-
1rations have a notable and manifeſt ſhare
in
thoſe obvious effects, that men have
already
been invited to aſcribe thereunto
ſuch
as are the various diſtempers inci­
dent
to humane Bodies, eſpecially if cra­
zy
, in the Spring, the Autumn, and alſo
on
moſt of the great and ſudden changes
of
Weather) but likewiſe, that the fur­
ther
diſcovery of the nature of the Ayr,
will
probably diſcover to us, that it con­
curs
more or leſs to the exhibiting of ma­
ny
Phænomena, in which it hath hither­
to
ſcarce been ſuſpected to have any inte­
reſt
.
So that a True Account of any
Experiment
that is New concerning a
thing
, wherewith we have ſuch conſtant
and
neceſſary intercourſe, may not one­
ly
prove of ſome advantage to humane
Life
, but gratifie Philoſophers, by pro­
moting
their Speculations on a Subject
which
hath ſo much opportunity to ſolli­
cite
their Curioſity.
And I ſhould immediately proceed to
the
mention of my Experiments, but that
I
like too well that worthy ſaying of the
Naturaliſt
Pliny, Benignum eſt

& plenum ingenui pudor is, fateri
per
quos profeceris, not to con­
form
to it, by acquainting your Lord-
1ſhip, in the firſt place, with the Hint I
had
of the Engine I am to entertain you
of
.
You may be pleaſ'd to remember,
that
a while before our ſeparation in Eng­
land
, I told you of a Book that I had
heard
of, but not peruſ'd, publiſh'd by
the
induſtrious Jeſuit Schottus, wherein
'twas ſaid, He related how that ingenious
Gentleman
Otto Gericke, Conſul of Mag­
deburg
, had lately practiced in Germany a
way
of emptying Glaſs Veſſels, by ſuck­
ing
out the Ayr at the mouth of the Veſ­
ſel
, plung'd under water: And you may
alſo
perhaps remember, that I expreſſ'd
my
ſelf much delighted with this Expe­
riment
, ſince thereby the great force of
the
external Air (either ruſhing in at the
open
'd Orifice of the empty'd Veſſel, or
violently
forcing up the Water into it)
was
rendred more obvious and conſpicu­
ous
, than in any Experiment that I had
formerly
ſeen.
And though it may appear
by
ſome of thoſe Writings I ſometimes
fhew
'd your Lordſhip, that I had been ſol­
licitous
to try things upon the ſame
ground
; yet in regard this Gentleman
was
before-hand with me in producing
ſuch
conſiderable effects, by means of the
exſuction
of Air, I think my ſelf oblig'd
1to acknowledge the Aſſiſtance, and En­
couragement
the Report of his perfor­
mances
hath afforded me.
In .
lib. 1.
But as few inventions happen to be at
firſt
ſo compleat, as not to be either ble­
miſhd
with ſome deficiencies needful to be
remedy
'd, or otherwiſe capable of im­
provement
: ſo when the Engine we
have
been ſpeaking of, comes to be more
attentively
conſider'd, there will appear
two
very conſiderable things to be de­
ſir
'd in it.
For firſt, the Wind-Pump (as
ſome
body not improperly calls it) is ſo
contriv
'd, that to evacuate the Veſſel
there
is requir'd the continual labor of
two
ſtrong men for divers hours.
And
next
(which is an imperfection of much
greater
moment) the Receiver, or Glaſs
to
be empty'd, conſiſting of one entire
and
uninterrupted Globe and Neck of
Glaſs
; the whole Engine is ſo made, that
things
cannot be convey'd into it, where­
on
to try Experiments: So that there
ſeems
but little (if any thing) more to be
expected
from it, then thoſe very few
Phænomena that have been already ob­
ſerv
'd by the Author, and Recorded by
Schottus. Wherefore to remedy theſe
Inconveniences
, I put both Mr. G.
1and R. Hook (who hath alſo the Honor to
be
known to your Lordſhip, and was with
me
when I had theſe things under conſi­
deration
) to contrive ſome Air Pump,
that
might not, like the other, need to
be
kept under water (which on divers oc­
caſions
is inconvenient) & might be more
eaſily
manag'd: And after an unſucceſsful
try
all or two of ways propoſ'd by
thers
, the laſt nam'd Perſon fitted me
with
a Pump, anon to be deſcrib'd.
And
thus
the firſt Imperfection of the German
Engine
, was in good meaſure, though
not
perfectly, remedy'd: And to ſupply
the
ſecond deſect, it was conſidered that
it
would not perhaps prove impoſſible to
leave
in the Glaſs to be empty'd, a hole
large
enough to put in a Mans Arm
cloath
'd; and conſequently other Bodies,
not
bigger then it, or longer then the in­
ſide
of the Veſſel.
And this Deſign
ſeem
'd the more hopefull, becauſe I re­
membred
, that having ſeveral years be­
fore
often made the Experiment De Va­
cuo
with my own hands; I had, to exa­
mine
ſome conjectures that occurr'd to
me
about it, cauſed Glaſſes to be made
with
a hole at that end, which uſes to be
ſeal
'd up, and had nevertheleſs been able
1as occaſion requir'd, to make uſe of ſuch
Tubes
, as if no ſuch holes had been left
in
them; by deviſing ſtopples for them,
made
of the common Plaiſter call'd Dia­
chylon
: which I rightly enough gheſſ'd,
would
, by reaſon of the exquiſite com­
mixtion
of its ſmall parts, and cloſeneſs
of
its texture, deny all acceſs to the ex­
ternal
Air.
Wherefore, ſuppoſing that
by
the help of ſuch Plaiſters, carefully
laid
upon the commiſſures of the ſtopple
and
hole to be made in the Receiver, the
external
Air might be hindred from inſi­
nuating
it ſelf between them into the Veſ­
ſel
, we cauſ'd ſeveral ſuch Glaſſes, as
you
will finde deſcrib'd a little lower, to
be
blown at the Glaſs-houſe; and though
we
could not get the Work-men to blow
any
of them ſo large, or of ſo conveni­
ent
a ſhape as we would fain have had; yet
finding
one to be tolerably fit, and leſs
unfit
then any of the reſt, we were con­
tent
to make uſe of it in that En­
gine
: Of which, I ſuppoſe, you by this
time
expect the Deſcription, in order to
the
Recital of the Phænomena exhibited
by
it.
To give your Lordſhip then, in the
firſt
place, ſome account of the Engine it
1ſelf: It conſiſts of two principal parts; a
glaſs
Veſſel, and a Pump to draw the Air
out
of it.
The former of theſe (which we, with
the
Glaſs men, ſhall often call a Receiver,
for
its affinity to the large Veſſels of that
name
, uſed by Chymiſts) conſiſts of a
Glaſs
with a wide hole at the top, of a
cover
to that hole, and of a ſtop-cock
faſtned
to the end of the neck, at the
bottom
.
The ſhape of the Glaſs, you will find
expreſſ
'd in the firſt Figure of the annex­
ed
Scheme.
And for the ſize 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
ſhould
have been better pleaſ'd with a
more
capacious Veſſel, but the Glaſs-men
profeſſed
themſelves unable to blow a
larger
, of ſuch a thickneſs and ſhape as
was
requiſite to our purpoſe.
At the very top of the Veſſel, (A) you
may
obſerve a round hole, whoſe Dia­
meter
(B C) is of about four inches; and
whereof
, the Orifice is incircled with a
lip
of Glaſs, almoſt an inch high: For
the
making of which lip, it was requiſite
(to mention that upon the by, in caſe
1your Lordſhip ſhould have ſuch another
Engine
made for you) to have a hollow
and
tapering Pipe of Glaſs drawn out,
whereof
the Orifice above mentioned
was
the Baſis, and then to have the cone
cut
off with a hot Iron, within about an
Inch
of the Points (B C.)
The uſe of the lip, is to ſuſtain the
cover
delineated in the ſecond Figure;
where
(D E) points out a braſs Ring, ſo
caſt
, as that it doth within and without
cover
the lip (B C) of the firſt Figure,
and
is cemented on upon it with a ſtrong
and
cloſe Cement.
To the inward taper­
ing
Orifice of this Ring (which is about
three
Inches over) are exquiſitely ground
the
ſides of the Braſs ſtopple (F G;) ſo
that
the concave ſuperficies of the one,
and
the convex of the other, may touch
one
another in ſo many places, as may
leave
as little acceſs, as poſſible, to the ex­
ternal
Air: And in the midſt of this cover
is
left a hole (H I) of about half an inch
over
, invironed alſo with a ring or ſocket
of
the ſame mettal, and fitted likewiſe
with
a braſs ſtopple (K) made in the form
of
the Key of a ſtop-cock, and exactly
ground
into the hole (H I) it is to fill; ſo
as
that though it be turn'd round in the
1cavity it poſſeſſes, it will not let in the
Air
, and yet may be put in or taken out
at
pleaſure, for uſes to be hereafter men­
tioned
.
In order to ſome of which, it is
perforated
with a little hole, (8) traverſing
the
whole thickneſs of it at the lower
end
; through which, and a little braſs
Ring
(L) faſtned to one ſide, (no matter
which
) of the bottom of the ſtopple
(FG) a ſtring (8, 9, 10) might paſs, to
be
imploy'd to move ſome things in the
capacity
of the empty'd Veſſel; without
any
where unſtopping it.
The laſt thing belonging to our Recei­
ver
, is the ſtop-cock deſigned in the firſt
Figure
by (N.) for the better faſtening
of
which to the neck, and exacter excluſi­
on
of the Air, there was ſoder'd on to
the
ſhank of the Cock (X) a Plate of
Tin
, (MTUW) long enough to cover
the
neck of the Receiver.
But becauſe
the
cementing of this was a matter of
ſome
difficulty, it will not be amiſs 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
, Roſin, and Wood-aſhes, well in­
corporated
; and to hinder this liquid
Mixture
from getting into the Orifice (Z)
1of the ſhank, (X) that hole was ſtopt
with
a Cork, to which was faſtned a ſtring,
whereby
it might be pull'd out of the up­
per
Orifice of the Receiver; and then,
the
glaſs neck of the Receiver being well
warm
'd, was thruſt into this Cement, and
over
the ſhank whereby it was effected,
that
all the ſpace betwixt the tin Plate and
the
Receiver, and betwixt the internal
ſuperficies
of the Receiver, and the
ſhanck
of the Cock, was filld with the
Cement
; and ſo we have diſpach'd the
firſt
and upper part of the Engine.
The undermoſt remaining part conſiſts
of
a Frame, and of a ſucking Pump, or
as
we formerly call'd it, an Air Pump, ſup­
ported
by it: The Frame is of Wood,
ſmall
, but very ſtrong, conſiſting of three
legs
, (111) ſo plac'd, that one ſide of
it
may ſtand perpendicular, that the free
motion
of the hand may not be hindered.
In the midſt of which frame, is tranſverſly
nail
'd a board, (222) which may not im­
properly
be call'd a Midriff, upon which
reſts
, and to which is ſtrongly faſtned, the
main
part of the Pump it ſelf, which is
the
onely thing remaining to be deſcri­
bed
.
The Pump conſiſts of four parts, a
1hollow Cylindre, a Sucker, a handle to
move
that Sucker, and a Valve.
The Cylindre was (by a pattern) caſt
of
braſs; it is in length about 14 inches,
thick
enough to be very ſtrong, notwith­
ſtanding
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 ſuck­
er
, (4455) conſiſting of two parts, the
one
(44) ſomewhat leſs in Diameter then
the
cavity of the Cylindre, upon which
is
nail'd a good thick piece of tan'd ſhoe
Leather
, which will go ſo cloſe 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 inſinuating it ſelf be­
twixt
it and the ſides of the Cylindre
whereon
it is to move.
To the midſt of this former part of the
Sucker
is ſtrongly faſtned the other,
namely
a thick and narrow plate of Iron,
(55) ſomewhat longer then the Cylindre,
one
of whoſe edges is ſmooth, but at the
other
edge it is indented (as I may ſo
ſpeak
) with a row of teeth delineated in
1the Scheme, into whoſe intervals are to
be
fitted, the teeth of a ſmall Iron nut;
() (as Tradeſ-men call it) which is faſt­
ned
by two ſtaples (22) to the under ſide
of
the formerly mention'd tranſverſe
board
(222) on which the Cylindre reſts,
and
is turn'd to and fro by the third piece
of
this Pump, namely, the handle or
manubrium, (7) of which the Figure gives
a
ſufficient deſcription.
The fourth and laſt part of this Cylin­
dre
, is the Valve, (R) conſiſting 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 braſs, to be thruſt in, and taken
out
at pleaſure.
The Engine being thus deſcrib'd, it
will
be requiſite to adde, that ſomething
is
wont to be done before it be ſet on
work
, for the more eaſie moving of the
Sucker
, and for the better excluſion of
the
outward Air: which when the Veſſel
begins
to be exhauſted, is much more dif­
ficult
to be kept out then one would eaſi­
ly
imagine.
There muſt then be firſt powr'd in at
the
top of the Receiver a little ſallad oyl,
partly
to fill up any ſmall intervalls that
1may happen to be betwixt the contigu­
ous
ſurfaces of the internal parts of the
Stop-cock
: And partly that it may be
the
more eaſie to turn the Key (S) back­
wards
and forwards.
Pretty ſtore of oyl
muſt
alſo be pour'd into the Cylindre,
both
that the Sucker may ſlip up and
down
in it the more ſmoothly and freely,
and
that the Air might be the better
hindred
from getting in between them:
And
for the like reaſons, a little oyl is to
be
uſed alſo about the Valve.
Upon
which
occaſion, it would not be omitted
(for it is ſtrange) that oftentimes, when
neither
the pouring in of water, nor even
of
oyl alone, prov'd capable to make the
Sucker
move eaſily enough in the Cylin­
der
; a mixture of both thoſe Liquors
would
readily (ſometimes even to admi­
ration
) perform the deſired effect.
And
laſtly
, the braſs cover of the Receiver,
being
put into the braſs ring formerly de­
ſcrib
'd, that no Air may get between
them
, it will be very requiſite to plaiſter
over
very carefully the upper edges of
both
, with the plaiſter formerly mention­
ed
, or ſome other as cloſe, which is to be
ſpread
upon the edges with a hot Iron;
that
being melted, it may run into and
1fill up all the crannies, or other little ca­
vities
, at which the Air might otherwiſe
get
entrance.
All things being thus fitted, and the
lower
ſhank (O) of the ſtop-cock being
put
into the upper Orifice of the Cylin­
der
(&), into which it was exactly ground;
the
Experimenter is firſt, 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 ſhut­
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
thruſt
out, and none being permitted to
ſucceed
in its room, 'tis manifeſt that the
cavity
of the Cylinder muſt be empty,
in
reference to the Air: So that if there­
upon
the Key of the Stop-cock be ſo
turn
'd, as that through the perforation of
it
, a free paſſage be opened betwixt the
Cylinder
and the Receiver, part of the
Air
formerly contain'd in the Receiver,
will
nimbly deſcend 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
1of 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 ſtopping
the
Valve, as occaſion requires, more or
leſs
Air may be ſuck'd out of the Recei­
ver
, according to the exigency of the Ex­
periment
, and the intention of him that
makes
it.
Your Lordſhip will, perhaps, think that
I
have been unneceſſarily prolix in this
firſt
part of my Diſcourſe: But if you
had
ſeen how many unexpected difficul­
ties
we found to keep out the externall
Air
, even for a little while, when ſome
conſiderable
part of the internal had been
ſuckt
out; You would peradventure al­
low
, that I might have ſet down more
circumſtances
then I have, without ſet­
ting
down any, whoſe knowledge, he that
ſhall
try the Experiment may not have
need
of.
Which is ſo true, that, before we
proceed
any further, I cannot think it un­
ſeaſonable
to advertiſe Your Lordſhip,
that
there are two chief ſorts of Experi­
ments
, which we deſign'd in our Engine
to
make tryal of: The one, ſuch as may
1be quickly diſpatcht, and therefore may
be
try'd in our Engine, though it leak a
little
; becauſe the Air may be faſter drawn
out
, by nimbly plying the Pump, then
it
can get in at undiſcern'd leaks; I ſay at
undiſcern
'd leaks, becauſe ſuch as are big
enough
to be diſcover'd can ſcarce be un­
eaſie
to be ſtopt.
The other ſort of Ex­
periments
conſiſts of thoſe that require
not
onely that the internal Air be drawn
out
of the Receiver, but that it be like­
wiſe
for a long time kept out of it.
Such
are
the preſervation of Animal and
ther
Bodies therein, the germination and
growth
of Vegetables, and other tryals
of
ſeveral ſorts, which it is apparent can­
not
be well made unleſs the external Air
can
, for a competent while, be excluded:
Since
even at a very ſmall leak there may
enough
get in, to make the Vacuum ſoon
looſe
that name; by which I here declare
once
for all, that I underſtand not a ſpace
wherein
there is no body at all, but ſuch
as
is either altogether, or almoſt totally
void
of Air.
Now this diſtinction of Experiments
I
thought fit to premiſe to the enſuing
Narratives
, becauſe upon tryal, we found
it
ſo exceeding (and ſcarce imaginable) dif-
1ficult a matter, to keep out the Air from
getting
at all in at any imperceptible hole
or
flaw whatſoever, in a Veſſel immedi­
ately
ſurrounded with the compreſſed At­
moſphere
, that in ſpight of all our care
and
diligence, we never were able totally
to
exhauſt the Receiver, or keep it when
it
was almoſt empty, any conſiderable
time
, from leaking more or leſs: although
(as we have lately intimated) by unwearyed
quickneſs
in plying the Pump, the inter­
nall
Air can be much faſter drawn out
then
the external can get in, till the Re­
ceiver
come to be almoſt quite empty.
And that's enough to enable men to diſ­
cover
hitherto unobſerved Phænomena of
Nature
.
The Experiments therefore of the firſt
ſort
, will, I fear, prove the onely ones
wherewith
my Avocations will allow me
to
entertain Your Lordſhip in this Letter.
For till your further Commands ſhall en­
gage
me to undertake, by Gods permiſ­
ſion
, ſuch an Employment, and more lea­
ſure
ſhall better fit me for it, I know not
whether
I ſhall be in a condition to try
what
may be done, to enable me to give
you
ſome account of the other ſort of
Experiments
alſo.
1
TO proceed now to the Phænomena,

exhibited
to us by the Engine above
deſcribed
; I hold it not unfit to begin
with
what does conſtantly and regularly
offer
it ſelf to our obſervation, as depend­
ing
upon the Fabrick of the Engine it ſelf,
and
not upon the nature of this or that
particular
Experiment which 'tis employ­
ed
to try.
Experi­
ment
1.
Firſt, Then upon the drawing down
of
the Sucker, (the Valve being ſhut) the
Cylindrical
ſpace, deſerted 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 ruſhes into the em­
ptyed
Cylinder, till the Air in both thoſe
Veſſels
be brought to about an equal
meaſure
of dilatation.
And therefore,
upon
ſhutting the Receiver by returning
the
Key, if you open the Valve, and force
up
the Sucker again, you will finde, that
after
this firſt exſuction you will drive
out
almoſt a whole Cylinder full of Air:
But
at the following exſuctions, you will
draw
leſs and leſs of Air out of the Recei­
ver
into the Cylinder, becauſe that there
will
ſtill remain leſs and leſs Air in the
1Receiver it ſelf; and conſequently, the
Particles
of the remaining Air, having
more
room to extend themſelves in, will
leſs
preſs out one another.
This you will
eaſily
perceive, by finding, that you ſtill
force
leſs and leſs Air out of the Cylin­
der
; ſo that when the Receiver is almoſt
exhauſted
, you may force up the Sucker
almoſt
to the top of the Cylinder, be­
fore
you will need to unſtop the Valve to
let
out any Air: And if at ſuch time, the
Valve
being ſhut, 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 protruſion of the external Air;
which
, being much leſs rarified then that
within
the Cylinder, muſt have a more
forcible
preſſure upon the Sucker, then
the
internal is able to reſiſt: And by this
means
you may know how far you have
emptyed
the Receiver.
And to this we
may
adde, on this occaſion, that conſtant­
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 conſiderably brisk noiſe, eſpeci­
ally
whil'ſt there is any plenty of Air in
the
Receiver.
1
For the more eaſie underſtanding of the
Experiments
tryable by our Engine, I
thought
it not ſuperfluous, nor unſeaſon­
able
in the recital of this firſt of them, to
inſinuate
that notion by which it ſeems
likely
that moſt, if not all, of them will
prove
explicable.
Your Lordſhip will
eaſily
ſuppoſe, that the Notion I ſpeak
of
is, That there is a Spring, or Elaſti­
cal
power in the Air we live in.
By which
ἐλατγ̀ρ or Spring of the Air, that which
I
mean is this: That our Air either con­
ſiſts
of, or at leaſt abounds with, parts of
ſuch
a nature, that in caſe they be bent or
compreſſ
'd by the weight of the incum­
bent
part of the Atmoſphere, or by any
ther
Body, they do endeavor, as much as
in
them lies, to free themſelves from that
preſſure
, by bearing againſt the contigu­
ous
Bodies that keep them bent; and,
aſſoon
as thoſe Bodies are remov'd or
reduced
to give them way, by preſently
unbending
and ſtretching out themſelves,
either
quite, or ſo far forth as the con­
tiguous
Bodies that reſiſt them will per­
mit
, and thereby expanding the whole
parcel
of Air, theſe elaſtical Bodies com­
poſe
.
1
This Notion may perhaps be ſome­
what
further explain'd, by conceiving the
Air
near the Earth to be ſuch a heap of
little
Bodies, lying one upon another, as
may
be reſembled to a Fleece of Wooll.
For this (to omit other likeneſſes betwixt
them
) conſiſts of many ſlender and flexi­
ble
Hairs; each of which, may indeed,
like
a little Spring, be eaſily bent or roul­
ed
up; but will alſo, like a Spring, be
ſtill
endeavouring to ſtretch it ſelf out
again
.
For though both theſe Haires,
and
the Aerial Corpuſcles to which we
liken
them, do eaſily yield to externall
preſſures
; yet each of them (by vertue of
its
ſtructure) is endow'd with a Power or
Principle
of ſelf-Dilatation; by vertue
whereof
, though the hairs may by a Mans
hand
be bent and crouded cloſer together,
and
into a narrower room then ſuits beſt
with
the nature of the Body: Yet whil'ſt
the
compreſſion laſts, there is in the fleece
they
compoſe an endeavour outwards,
whereby
it continually thruſts againſt the
hand
that oppoſes its Expanſion.
And
upon
the removall of the external preſ­
ſure
, by opening the hand more or leſs, the
compreſſed
Wooll does, as it were, ſpon­
taneouſly
expand or diſplay it ſelf towards
1the recovery of its former more looſe and
free
condition, till the Fleece have ei­
ther
regain'd its former Dimenſions, or
at
leaſt, approach'd them as near as the
compreſſing
hand (perchance not quite
open
'd) will permit.
This Power of
ſelf-Dilatation
, is ſomewhat more conſpi­
cuous
in a dry Spunge compreſſ'd, then
in
a Fleece of Wooll.
But yet we ra­
ther
choſe to imploy the latter, on this
occaſion
, becauſe it is not like a Spunge,
an
entire Body, but a number of ſlen­
der
and flexible Bodies, looſely com­
plicated
, as the Air it ſelf ſeems to
be
.
There is yet another way to explicate
the
Spring of the Air, namely, by ſuppo­
ſing
with that moſt ingenious Gentleman,
Monſieur
Des Cartes, That the Air is no­
thing
but a Congeries or heap of ſmall
and
(for the moſt part) of flexible Parti­
cles
; of ſeveral ſizes, and of all kinde of Fi­
gures
which are raiſ'd by heat (eſpecially
that
of the Sun) into that fluid and
ſubtle
Etheriall Body that ſurrounds
the
Earth; and by the reſtleſſe agi­
tation
of that Celeſtial Matter where­
in
thoſe Particles ſwim, are ſo whirl'd
1round, that each Corpuſcle endeavours
to
beat off all others from coming within
the
little Sphear requiſite to its motion
about
its own Center; and (in caſe any,
by
intruding into that Sphear ſhall op­
poſe
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 ſtructure re­
quiſite
to Springs, or be of any other
form
(how irregular ſoever) ſince their
Elaſtical
power is not made to depend
upon
their ſhape or ſtructure, but upon
the
vehement agitation, and (as it were)
brandiſhing
motion, which they receive
from
the fluid Ether that ſwiftly flows
between
them, and whirling about each
of
them (independently from the reſt)
not
onely keeps thoſe ſlender Aërial
Bodies
ſeparated and ſtretcht out (at leaſt,
as
far as the Neighbouring ones will per­
mit
) which otherwiſe, by reaſon of
their
flexibleneſs and weight, would
flag
or curl; but alſo makes them hit
againſt
, and knock away each other, and
conſequently
require more room, then
that
which if they were compreſſ'd, they
would
take up.
1
By theſe two differing ways, my Lord,
may
the Spring of the Air be explicated.
But though the former of them be that,
which
by reaſon of its ſeeming ſomewhat
more
eaſie, I ſhall for the moſt part make
uſe
of in the following Diſcourſe: yet
am
I not willing to declare peremptorily
for
either of them, againſt the other.
And
indeed
, though I have in another Treatiſe
endeavoured
to make it probable, that the
returning
of Elaſtical Bodies (if I may ſo
call
them) forcibly bent, to their former
poſition
, may be Mechanically explica­
ted
: Yet I muſt confeſs, that to deter­
mine
whether the motion of Reſtitution
in
Bodies, proceed from this, That the
parts
of a Body of a peculiar Structure
are
put into motion by the bending of the
ſpring
, or from the endeavor of ſome ſub­
tle
ambient Body, whoſe paſſage may be
oppoſ
'd or obſtructed, or elſe it's preſſure
unequally
reſiſted by reaſon of the new
ſhape
or magnitude, which the bending of
a
Spring may give the Pores of it: To
determine
this, I ſay, ſeems to me a mat­
ter
of more difficulty, then at firſt ſight
one
would eaſily imagine it.
Wherefore
I
ſhall decline medling with a ſubject,
which
is much more hard to be explica-
1ted, then neceſſary to be ſo, by him,
whoſe
buſineſs it is not, in this Letter, to
aſſign
the adequate cauſe of the Spring of
the
Air, but onely to manifeſt, That the
Air
has a Spring, and to relate ſome of
its
effects.
I know not whether I need annex that,
though
either of the above-mention'd
Hypotheſes
, and perhaps ſome others,
may
afford us an account plauſible enough
of
the Air-ſpring; yet I doubt, whether
any
of them gives us a ſufficient account
of
its Nature.
And of this doubt, I
might
here mention ſome Reaſons, but
that
, peradventure, I may (God permit­
ting
) have a fitter occaſion to ſay ſome­
thing
of it elſewhere.
And therefore I
ſhould
now proceed to the next Experi­
ment
, but that I think it requiſite, firſt,
to
ſuggeſt to your Lordſhip what comes
into
my thoughts, by way of Anſwer to
a
plauſible Objection, which I foreſee you
may
make againſt our propoſ'd Doctrine,
touching
the Spring of the Air.
For it
may
be alleadged, that though the Air
were
granted to conſiſt of Springy Par­
ticles
(if I may ſo ſpeak) yet thereby
we
could onely give an account of the
Dilatation
of the Air in Wine-Guns and
1other pneumatical Engines wherein the
Air
has been compreſſ'd, and its Springs
violently
bent by an apparent externall
force
; upon the removall of which, 'tis
no
wonder that the Air ſhould, by the
motion
of reſtitution, expand it ſelf till
it
have recovered its more natural dimen­
ſions
: whereas in our above-mentioned
firſt
Experiment, and in almoſt all others
tryable
in our Engine, it appears not
that
any compreſſion of the Air prece­
ded
its ſpontaneous Dilatation or Expan­
ſion
of it ſelf.
To remove this difficul­
ty
, I muſt deſire Your Lordſhip 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 Atmoſ­
phere
we live in is not (otherwiſe then
comparatively
to more ponderous Bodies)
light
, but heavy: And did not their
gravity
hinder them, it appears not why
the
ſteams of the Terraqueous Globe, of
which
our Air in great part conſiſts,
ſhould
not riſe much higher then the Re­
fraction
of the Sun, and other Stars
give
men ground to think, that the At­
moſphere
, even in the judgement of thoſe
1Recent Aſtronomers, who ſeem willing
to
enlarge its bounds as much as they dare,
does
reach.
But leſt you ſhould expect my ſeconding
this
Reaſon by Experience; and leſt you
ſhould
object, That moſt of the Experi­
ments
that have been propoſ'd to prove the
gravity
of the Air, have been either barely
propoſ
'd, or perhaps not accuratly try'd; I
am
content, before I paſs further, to menti­
on
here, That I found a dry lambs-bladder
containing
near about two thirds of a pint,
and
compreſſ'd by a packthred tyed about
it
, to looſe a grain and the eighth part of
a
grain of its former weight, by the receſs
of
the Air upon my having prickt it: And
this
with a pair of Scales, which when the
full
Bladder and the correſpondent weight
were
in it, would manifeſtly turn either
way
with the 32 part of a grain.
And if
it
be further objected, That the Air in
the
Bladder was violently compreſſ'd by
the
Pack-thred and the ſides of the
Bladder
, we might probably (to wave
prolix
anſwers) be furniſh'd with a Re­
ply
, by ſetting down the differing weight
of
our Receiver, when empty'd and when
full
of uncompreſſ'd Air, if we could here
procure
ſcales fit for ſo nice an experiment;
1ſince we are informed, that in the German
Experiment
, commended at the begin­
ning
of this Letter, the Ingenious Tryers
of
it found, That their Glaſs Veſſel, of
the
capacity of 32 meaſures, was lighter
when
the Air had been drawn out of it,
then
before, by no leſs then one ounce
and
(3/10) that is, an ounce and very near a
third
: But of the gravity of the Air, we
may
elſewhere have occaſion to make fur­
ther
mention.
Taking it then for granted that the Air
is
not deyoid of weight, it will not be
uneaſie
to conceive, that that part of the
Atmoſphere
wherein we live, being the
lower
part of it, the Corpuſcles that com­
poſe
it, are very much compreſſ'd by the
weight
of all thoſe 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 Atmoſ­
phere
.
And though the height of this
Atmoſphere
, according to the famous
Kepler, and ſome others, ſcarce exceeds
eight
common miles; yet other eminent
and
later Aſtronomers, would promote
the
confines of the Atmoſphere, to ex­
ceed
ſix or ſeven times that number of
miles
.
And the diligent and learned
1Riviolo makes it probable, that the At­
moſphere
may, at leaſt in divers places, be
at
leaſt 50 miles high.
So that according to
a
moderate eſtimate of the thickneſs of
the
Atmoſphere, we may well ſuppoſe,
that
a Column of Air, of many miles in
height
, leaning upon ſome ſpringy Cor­
puſcles
of Air here below, may have
weight
enough to bend their little ſprings,
and
keep them bent: As, to reſume our
former
compariſon, if there were fleeces of
Wooll
pil'd up to a mountainous height
upon
one another, the Hairs that com­
poſe
the lowermoſt locks which ſupport
the
reſt, would, by the weight of all the
Wool
above them, be as well ſtrongly
compreſſed
, as if a man ſhould ſqueeze
them
together in his hands, or imploy any
ſuch
other moderate force to compreſs
them
.
So that we need not wonder, that
upon
the taking off the incumbent Air
from
any parcel of the Atmoſphere here
below
, the Corpuſcles, whereof that un­
dermoſt
Air conſiſts, ſhould diſplay them­
ſelves
, and take up more room then be­
fore
.
And if it be objected, That in Water,
the
weight of the upper and of the lower
part
is the ſame: I anſwer, That beſides
1that it may be well doubted whether the
obſervation
, by reaſon of the great diffi­
culty
have been exactly made, there is a
manifeſt
diſparity betwixt the Air and
Water
: For I have not found, that upon
an
Experiment purpoſely made, (and in
another
Treatiſe Recorded) that Water
will
ſuffer any conſiderable compreſſion;
whereas
we may obſerve in Wind-Guns
(to mention now no other Engines) that
the
Air will ſuffer it ſelf to be crouded in­
to
a comparatively very little room; in
ſo
much, that a very diligent Examiner
of
the Phænomena of Wind-Guns would
have
us believe, that in one of them, by
condenſation
, he reduc'd the Air into a
ſpace
at leaſt eight times narrower then it
before
poſſeſt.
And to this, if we adde
a
noble Phænomenon of the Experiment
De Vacuo; theſe things put together, may
for
the preſent ſuffice to countenance our
Doctrine
.
For that noble Experimenter,
Monſieur
Paſcal (the Son) had the com­
mendable
Curioſity to cauſe the Torri­
cellian
Experiment to be try'd at the foot,
about
the middle, and at the top of that
high
Mountain (in Auvergne, if I miſtake
not
) commonly call'd Le Puy de Domme;
whereby
it was found, That the Mercury
1in the Tube fell down lower, about three
inches
, at the top of the Mountain then
at
the bottom.
And a Learned Man a
while
ſince inform'd me, That a great
Virtuoſo, friend to us both, has, with not
unlike
ſucceſs, tryed the ſame Experi­
ment
in the lower and upper parts of a
Mountain
in the Weſt of England: Of
which
, the reaſon ſeems manifeſtly enough
to
be this, That upon the tops of high
Mountains
, the Air which bears againſt
the
reſtagnant Quick-ſilver, is leſs preſſ'd
by
the leſs ponderous incumbent Air; and
conſequently
is not able totally to hinder
the
deſcent of ſo tall and heavy a Cylin­
der
of Quick-ſilver, as at the bottom of
ſuch
Mountains did but maintain an Æqui­
librium
with the incumbent Atmoſphere.
And if it be yet further Objected
gainſt
what hath been propoſ'd touching
the
compactneſs and preſſure 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 ſuch
ther
light and weak Bodies; which ſeems
to
argue, that the particles of our Air are
not
ſo compreſſ'd as we have repreſented
them
, eſpecially, ſince by our former
Experiment
it appears, that the Air rea-
1dily dilated it ſelf downward, from the
Receiver
into the Pump, when 'tis plain,
that
it is not the incumbent Atmoſphere,
but
onely the ſubjacent Air in the braſs
Cylinder
that has been remov'd: If this,
I
ſay, be objected, we may reply, That
when
a man ſqueezes a Fleece of Wool in
his
hand, he may feel that the Wool in­
ceſſantly
bears againſt his hand, as that
which
hinders the hairs it conſiſts of, to
recover
their former and more natural ex­
tent
.
So each parcel of the Air about the
Earth
, does conſtantly endeavour to thruſt
away
all thoſe contiguous Bodies, whe­
ther
Aërial or more groſs, that keep
them
bent, and hinder the expanſion of
its
parts, which will dilate themſelves or
flie
abroad towards that part, whether up­
wards
or downwards, where they finde
their
attempted Dilatation of themſelves
leſs
reſiſted by the neihgboring Bodies.
Thus the Corpuſcles of that Air we have
been
all this while ſpeaking of, being un­
able
, by reaſon of their weight, to aſcend
above
the Convexity of the Atmoſphere,
and
by reaſon of the reſiſtance of the ſur­
face
of the Earth and Water, to fall down
lower
, they are forced, by their own gra­
vity
and this reſiſtance, to expand and
1diffuſe themſelves about the Terreſtial
Globe
; whereby it comes to paſs, that
they
muſt as well preſs the contiguous
Corpuſcles
of Air that on either ſide op­
poſe
their Dilatation, as they muſt preſs
upon
the ſurface of the Earth, and, as it
were
recoyling thence, endeavor to thruſt
away
thoſe upper particles of Air that
lean
upon them.
And as for the eaſie yielding of the Air
to
the Bodies that move in it, if we con­
ſider
that the Corpuſcles whereof it con­
ſiſts
, though of a ſpringy nature, are yet
ſo
very ſmall, as to make up (which 'tis
manifeſt
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 conſiſts of are in an almoſt
reſtleſs
motion, whereby they become
(as we have more fully diſcourſed in ano­

ther
Treatiſe) very much diſpoſed to
yield
to other Bodies, or eaſie to be diſ­
plac
'd by them, and that the ſame Cor­
puſcles
are likewiſe ſo variouſly mov'd, as
they
are intire Corpuſcles, that if ſome
ſtrive
to puſh a Body plac'd among them
towards
the right hand (for inſtance)
others
, whoſe motion has an oppoſite de­
termination
, as ſtrongly thruſt the ſame
1Body towards the left; whereby neither
of
them proves able to move it out of
its
place, the preſſure on all hands being
reduced
as it were to an Æquilibrium: ſo
that
the Corpuſcles of the Air muſt be as
well
ſometimes conſidered under the no­
tion
of little Springs, which remaining
bent
, are in their entire bulk tranſported
from
place to place; as under the notion
of
Springs diſplaying themſelves, whoſe
parts
flie abroad whilſt as to their entire
bulk
they ſcarce change place: As the
two
ends of a Bow, ſhot off, fly from one
another
, whereas the Bow it ſelf may be
held
faſt in the Archers hand; and that it
is
the equal preſſure of the Air on all ſides
upon
the Bodies that are in it, which cau­
ſes
the eaſie Ceſſion 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 ſide of a Body without being
drawn
away from the other; he that ſhall
think
to move that Body too and fro, as
eaſily
as before, will finde himſelf much
miſtaken
.
In a Diſ­
courſe

touching

ſluidity

and
firm­
neſs
.
In verification of which we will, to di­
vert
your Lordſhip a little, mention here
a
Phænomenon of our Engine, which even
1to divers ingenious perſons has at firſt
ſight
ſeem'd very wonderful.
THe thing that is wont to be admired,

and
which may paſs for our ſecond
Experiment
is this, That if, when the
Receiver
is almoſt empty, a By-ſtander
be
deſired to lift up the braſs Key (former­
ly
deſcribed as a ſtopple in the braſs Co­
ver
) he will finde it a very difficult thing
to
do ſo, if the Veſſel be well exhauſted;
and
even when but a moderate quantity of
Air
has been drawn out, he will, when he
has
lifted it up a little, ſo that it is ſome­
what
looſe from the ſides of the lip or
ſocket
, which (with the help of a little
oyl
) it exactly filled before, he will (I ſay)
finde
it ſo difficult to be lifted up, that
he
will imagine there is ſome great weight
faſtned
to the bottom of it.
And if (as
ſometimes
has been done for merriment)
onely
a Bladder be tyed to it, it is plea­
ſant
to ſee how men will marvail that ſo
light
a Body, filled at moſt but with Air,
ſhould
ſo forcibly draw down their hand
as
if it were fill'd with ſome very ponder­
ous
thing: whereas the cauſe of this pret­
ty
Phænomenon ſeems plainly enough to
1be onely this, That the Air in the Recei­
ver
, being very much dilated, its Spring
muſt
be very much weakn'd, and conſe­
quently
it can but faintly preſs up the
lower
end of the ſtopple, whereas the
Spring
of the external Air being no way
debilitated
, he that a little lifts up the
ſtopple
muſt with his hand ſupport a preſ­
ſure
equal to the diſproportion betwixt
the
force of the internal expanded Air, and
that
of the Atmoſphere incumbent upon
the
upper part of the ſame key or ſtopple:
And
ſo men being unuſ'd to finde any re­
ſiſtance
, in lifting things up, from the
free
Air above them, they are forward to
conclude
that that which depreſſes their
hands
muſt needs be ſome weight, though
they
know not where plac'd, drawing be­
neath
it.
Experi­
ment
2.
And that we have not miſ-aſſign'd the
cauſe
of this Phænomenon ſeems evident
enough
by this; That as Air is ſuffer­
ed
by little and little to get into the Re­
ceiver
, the weight that a man fancies his
hand
ſupports is manifeſtly felt to decreaſe
more
and more, the internal Air by this
recruit
approaching more to an Æquili­
brium
with the external, till at length the
Receiver
growing again full of Air, the
1ſtopple may be lifted up without any dif­
ficulty
at all.
By ſeveral other of the Experiments
afforded
us by our Engine, the ſame no­
tion
of the great and equal preſſure of the
free
Air upon the Bodies it environs,
might
be here manifeſted, but that we
think
it not ſo fit to anticipate ſuch Ex­
periments
: And therefore ſhall rather
employ
a few lines to clear up a difficulty
touching
this matter, which we have ob­
ſerv
'd to have troubled ſome even of the
Philoſophical
and Mathematical Specta­
tors
of our Engine, who have wonder'd
that
we ſhould talk of the Air exquiſitely
ſhut
up in our Receiver, as if it were all
one
with the preſſure of the Atmoſphere;
whereas
the thick and cloſe body of the
Glaſs
, wholly impervious to the Air, does
manifeſtly
keep the incumbent Pillar of
the
Atmoſphere from preſſing in the leaſt
upon
the Air within the Glaſs, which it
can
no where come to touch.
To eluci­
date
a little this matter, let us conſider,
That
if a man ſhould take a fleece of
Wool
, and having firſt by compreſſing it
in
his hand reduc'd it into a narrower com­
paſs
, ſhould nimbly convey and ſhut it
cloſe
up into a Box juſt fit for it, though
1the force of his hand would then no lon­
ger
bend thoſe numerous ſpringy Body's
that
compoſe the Fleece, yet they would
continue
as ſtrongly bent as before, be­
cauſe
the Box they are incloſ'd in would
as
much reſiſt their re-expanding of
themſelves
, as did the hand that put them
in
.
For thus we may conceive, that the
Air
being ſhut up, when its parts are bent
by
the whole weight of the incumbent
Atmoſphere
, though that weight can no
longer
lean upon it, by reaſon it is kept
off
by the Glaſs, yet the Corpuſcles of
the
Air within that Glaſs continue as
forcibly
bent as they were before their in­
cluſion
, becauſe the ſides of the Glaſs
hinder
them from diſplaying or ſtretch­
ing
out themſelves.
And if it be ob­
jected
that this is unlikely, becauſe ev'n
Glaſs
bubles, ſuch as are wont to be
blown
at the flame of a Lamp, exceeding
thin
and Hermetically ſeal'd will not
break
; whereas it cannot be imagin'd
that
ſo thin a Priſon of Glaſs could re­
ſiſt
the Elaſtical force of all the included
Air
, if that Air were ſo compreſſ'd as we
ſuppoſe
.
It may be eaſily reply'd, That
the
preſſure of the inward Air againſt the
Glaſs
, is countervail'd by the equal preſ-
1ſure of the outward againſt the ſame Glaſs.
And we ſee in bubles, that by reaſon 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 alſo more conſpicuous in
thoſe
great Spherical bubles that boyes
ſometimes
blow with Water, to which
Sope
has given a Tenacity.
But that, if the
preſſure
of the ambient Air were remov'd,
the
internal Air may be able to break
thicker
Glaſſes then thoſe lately men­
tion
'd, will appear by ſome of the follow­
ing
Experiments; to which we ſhall there­
fore
now haſten, having, I fear, been but
too
prolix in this Excurſion, though we
thought
it not amiſs to annex to our firſt
Experiments
ſome general Conſiderati­
ons
touching the Spring of the Air, be­
cauſe
(this Doctrine being yet a ſtranger
to
the Schools) not onely we finde not
the
thing it ſelf to be much taken notice
of
; but of thoſe few that have heard of it,
the
greater part have been forward to re­
ject
it, upon a miſtaken Perſwaſion, that
thoſe
Phænomena are the effects of natures
abhorrency
of a Vacuum, which ſeem to
be
more fitly aſcribeable to the weight
and
Spring of the Air.
1
WE will now proceed to obſerve that

though
, by the help of the handle,
the
Sucker be eaſily drawn down to the
bottom
of the Cylinder; yet, without
the
help of that Leaver, there would be
required
to the ſame effect, a force or
weight
great enough to ſurmount the
preſſure
of the whole Atmoſphere: Since
otherwiſe
the Air would not be driven out
of
its place, when none is permitted to
ſucceed
into the place deſerted by the
Sucker
.
This ſeems evident, from the
known
Torricellian Experiment, in which,
if
the inverted Tube of Mercury be but
25
Digits high, or ſomewhat more, the
Quick-ſilver
will not fall but remain ſuſ­
pended
in the Tube; becauſe it cannot
preſs
the ſubjacent Mercury with ſo great
a
force, as does the incumbent Cylinder
of
the Air reaching thence to the top of
the
Atmoſphere: Whereas, if the Cy­
linder
of Mercury were three or four digits
longer
, it would over-power that of the
external
Air, and run out into the Veſſel'd
Mercury, till the two Cylinders came to
an
Æquilibrium, and no further. Hence
we
need not wonder, that though the
1Sucker move eaſily enough up and down
in
the Cylinder by the help of the Manu­
brium
; yet if the Manubrium be taken off,
it
will require & conſiderable ſtrength to
move
it either way.
Nor will it ſeem
ſtrange
, that if, when the Valve and
Stop-cock
are well ſhut, you draw down
the
Sucker, and then let go the Manubri­
um
; the Sucker will, as it were of it ſelf,
re-aſcend
to the top of the Cylinder, ſince
the
ſpring of the external Air findes no­
thing
to reſiſt its preſſing up the Sucker.
And for the ſame reaſon, when the Re­
ceiver
is almoſt 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 Manubrium, be
forcibly
carried up almoſt to the top of
the
Cylinder: Becauſe the Air within the
Cylinder
, being equally dilated and weak­
ned
with that of the Glaſs, is unable to
withſtand
the preſſure of the external Air,
till
it be driven into ſo little ſpace, that
there
is an Æquilibrium betwixt its force
and
that of the Air without.
And con­
gruouſly
hereunto we finde, that in this
caſe
, the Sucker is drawn down with little
1leſs difficulty, then if the Cylinder, be­
ing
devoid of Air, the Stop-cock were
exactly
ſhut: We might take notice of
ſome
other things, that depend upon the
Fabrick
of our Engine it ſelf; but to ſhun
prolixity
, we will, in this place, content
our
ſelves to mention one of them, which
ſeems
to be of greater moment then the
reſt
, and it is this; that when the Sucker
has
been impell'd to the top of the Cylin­
der
, and the Valve is ſo carefully ſtopp'd,
that
there is no Air left in the Cylinder
bove
the Sucker: If then the Sucker be
drawn
to the lower part of the Cylinder,
he
that manages the Pump findes not any
ſenſibly
greater difficulty to depreſs the
Sucker
, when it is nearer the bottom of the
Cylinder
, then when it is much further off.
Which circumſtance we therefore think fit
to
take notice of, becauſe an eminent Mo­
dern
Naturaliſt hath taught, that, when the
Air
is ſucked out of a Body, the violence
wherewith
it is wont to ruſh into it again,
as
ſoon as it is allow'd to re-enter, pro­
ceeds
mainly from this; That the preſſure
of
the ambient Air is ſtrengthned upon
the
acceſſion of the Air ſuck'd out; which,
to
make it ſelf room, forces the neighbor­
ing
Air to a violent-ſubingreſſion oſ its
parts
: which, iſ it were true, he that draws
1down the Sucker, would finde the reſiſt­
ance
of the external Air increaſ'd as he
draws
it lower, more of the diſplaced Air
being
thruſt into it to compreſs it.
But, by
what
has been diſcourſ'd upon the firſt
Experiment
, it ſeems more probable, that
without
any ſuch ſtrengthning of the preſ­
ſure
of the outward Air, the taking quite
away
or the debilitating of the reſiſtance
from
within, may ſuffice to produce the
effects
under conſideration.
But this will
perhaps
be illuſtrated by ſome or other of
our
future Experiments, and therefore
ſhall
be no longer inſiſted on here.
Experi­
ment
3.
HAving thus taken notice of ſome of

the
conſtant Phænomena of our En­
gine
it ſelf, let us now proceed to the Ex­
periments
tryable in it.
Experi­
ment
4.
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 cauſ'd the neck of it to be ſtrong­
ly
ty'd, ſo that none of the included Air,
though
by preſſure, could get out.
This
Bladder
being convey'd into the Receiver,
and
the Cover luted on, the Pump
was
ſet awork, and after two or three
exſuctions
of the ambient Air (where­
by
the Spring of that which remain'd in
1the Glaſs was weaken'd) the Impriſon'd
Air
began to ſwell in the Bladder, and as
more
and more of the Air in the Recei­
ver
was, from time to time, drawn out; ſo
did
that in the Bladder more and more ex­
pand
it ſelf, and diſplay the folds of the
formerly
flaccid Bladder: ſo that before we
had
exhauſted the Receiver near ſo much
as
we could, the Bladder appear'd as full
and
ſtretched, as if it had been blown up
with
a Quill.
And that it may appear that this plump­
neſs
of the Bladder proceeded from the
ſurmounting
of the debilitated Spring of
the
ambient Air remaining in the Veſſel,
by
the ſtronger 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 diſturb'd Air in the Bladder, was
proportionably
compreſſ'd into a narrow­
er
room, and the ſides 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.
1
This Experiment is much of the ſame
nature
with that which was ſome years
agoe
ſaid to be made by that eminent Ge­
ometrician
Monſieur Roberval, with a
Carps
Bladder empty'd and convey'd into
a
Tube, wherein the Experiment De Va­
cuo
was afterwards try'd, which ingeni­
ous
Experiment of his juſtly deſerves the
thanks
of thoſe that have been, or ſhall be
ſolicitous
to diſcover the nature of the
Air
.
But to return to our Experiment, we
may
take notice of this Circumſtance in
it
, That after the Receiver has been in
ſome
meaſure empty'd, the Bladder do's,
at
each exſuction, ſwell much more con­
ſpicuouſly
then it did at any of the firſt
Exſuctions
; inſomuch that towards the
end
of the pumping, not onely a great
fold
or cavity in the ſurface of the Blad­
der
may be made, even by the ſtretching
of
the inward ſelf-expanding Air: But
we
have ſometimes ſeen, upon the turn­
ing
of the Key to let the ambient Air
paſs
out of the Receiver into the Cylin­
der
, we have ſeen (I ſay) the Air in the
Bladder
ſuddenly expand it ſelf ſo much
and
ſo briskly, that it manifeſtly lifted up
ſome
light Bodies that lean'd upon it,
1and ſeem'd to lift up the Bladder it
ſelf
.
Now becauſe it has by very Learned
Men
been doubted whether the ſwelling
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 ſuppoſ'd in
our
Experiment to have return'd, like ſo
many
Springs to their wonted extent, up­
on
the removal of the Ambient Air that
compreſſ
'd and bent them: becauſe this,
I
ſay, has been doubted, we thought fit
to
make this further tryall.
We let down into the Receiver with
the
fore-mentioned Bladder two other
much
ſmaller, and of the ſame kinde of
Animal
; the one of theſe was not ty'd
up
at the neck that there might be liberty
left
to the Air that was not ſqueez'd out
(which might amount to about a fifth
part
of what the Bladder held before) to
paſs
out into the Receiver: The other had
the
ſides of it ſtretch'd out and preſſ'd to­
gether
, almoſt into the form of a Cup,
that
they might intercept the leſs Air be­
twixt
them, and then was ſtrongly ty'd
1up at the neck: This done, and the Air
being
in ſome meaſure ſuck'd out of the
Pneumatical
Glaſs (if I may ſo call it)
the
Bladder, mention'd at the beginning
of
our Experiment, appear'd extended
very
way to its full Dimenſions; whereas
neither
of the two others did remarkably
ſwell
, and that whoſe neck was not ty'd
ſeem
'd very little, if at all leſs wrinkl'd
then
when it was put in.
We made likewiſe a ſtrong Ligature
bout
the middle of a long Bladder part­
ly
empty'd, and upon the drawing the
Air
out of the Receiver, could obſerve
no
ſuch ſwelling betwixt the Ligature and
the
Neck of the Bladder, which had been
purpoſely
left open, as betwixt the ſame
Ligature
and the bottom of the Bladder,
whence
the included Air could no way
get
out.
But a further and ſufficient manifeſtati­
on
whence the intumeſſence of the Blad­
der
proceeds, may be deduc'd from the
following
Experiment.
TO try then at once both what it was

that
expanded the Bladder, and what
a
powerful Spring there is ev'n in the Air
1we are wont to think uncompreſſ'd, we
cauſ
'd a Bladder dry, well ty'd and blown
moderately
full, to be hung in the Recei­
ver
by one end of a ſtring, whoſe other
end
was faſtned to the inſide of the Co­
ver
: and upon drawing out the ambient
Air
, that preſſ'd on the Bladder; the in­
ternal
Air not finding the wonted reſiſt­
ance
, firſt ſwell'd and diſtended the Blad­
der
, and then broke it, with ſo wide and
crooked
a rent, as if it had been forcibly
torn
aſſunder with hands.
After which a
ſecond
Bladder being convey'd in, the Ex­
periment
was repeated with like ſucceſs:
And
I ſuppoſe it will not be imagin'd that
in
this caſe the Bladder was broken by its
own
Fibres, rather then by the Impri­
ſon
'd Air.
Experi­
ment
5.
And of this Experiment theſe two Phæ­
nomena
may be taken notice of: The one,
that
the Bladder at its breaking gave a
great
report, almoſt like a Craker: And
the
other, That the Air contain'd in the
Bladder
, had the power to break it with
the
mention'd Impetuoſity, long before
the
ambient Air was, all or near all, drawn
out
of the Receiver.
But, to verifie what we ſay in another
Diſcourſe
, where we ſhow, That even
1true Experiments may, by reaſon of
the
eaſie miſtake of ſome unheeded
Circumſtance
, be unſucceſsfully try'd;
we
will Advertiſe, on this occaſion,
that
we did oftentimes in vain try the
breaking
of Bladders, after the manner
above-mention
'd: Of which the cauſe
appear
'd to be this, That the Bladders we
could
not break, having been brought us
ready
blown from thoſe that ſold them,
were
grown dry before they came to our
hands
: whence it came to paſs, that, if
we
afterwards ty'd them very hard, they
were
apt to fret and ſo become unſervice­
able
; and if we ty'd them but moderate­
ly
hard, their ſtiffneſs kept them from be­
ing
cloſ'd ſo exactly, but that when the
included
Air had in the exhauſted Recei­
ver
diſtended them as much as eaſily it
could
, it would in part get out between
the
little wrinkles of the Sphincter of the
Neck
: Whence alſo it uſually 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 moiſt from the Butchers, we
could
, without injuring them, tye their
necks
ſo cloſe, that none of the Air once
1blown in, could get out of them, but by
violently
breaking them.
It will not be amiſs on this occaſion to
point
at ſomething which may deſerve a
more
deliberate Speculation then we can
now
afford it; namely that the Elaſtical
Power
of the ſame Quantity of Air may
be
as well Encreaſ'd by the Agitation of
the
Aërial Particles (whether onely mo­
ving
them more ſwiftly and ſcattering
them
, or alſo extending or ſtretching
them
out, I determine not) within an
every
way incloſing and yet yielding Bo­
dy
; as Diſplay'd by the withdrawing of
the
Air that preſſ'd it without.
For we
found
that a Bladder, but moderately
fill
'd with Air and ſtrongly 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
, ſuddenly broke with ſo loud and ve­
hement
a noiſe, as ſtony'd thoſe that were
by
, and made us, for a while after, almoſt
deaf
.
HAving thus ſeen that the Air has an

Elaſtical
Power, we were next deſi­
rous
to know in ſome meaſure how far a
1parcel of Air might by this its own Spring
be
dilated.
And though we were not pro­
vided
of Inſtruments fit to meaſure the
dilatation
of the Air any thing accurately,
yet
becauſe an imperfect meaſure of it was
more
deſireable then none at all, we de­
viſ
'd the following Method as very eaſily
practicable
.
Experi­
ment
6.
We took a limber Lambs Bladder
which
was thorowly wetted in fair Water,
that
the ſides of it being ſqueez'd roge­
ther
, there might be no Air left in its
folds
: (as indeed we could not afterwards
upon
tryal diſcern any) The neck of this
Bladder
was ſtrongly tyed about that of
a
ſmall Glaſs, (capable of holding five
full
drachmes of Water) the Bladder be­
ing
firſt ſo compreſſ'd, that all the inclu­
ded
Air was onely in the Glaſs, without
being
preſſ'd there; then the Pump be­
ing
ſet awork after a few exſuctions, the
Air
in the little Viol began to dilate it
ſelf
and produce a ſmall Tumor in the
Neck
of the Bladder; and as the ambi­
ent
Air was more and more drawn away,
ſo
the included Air penetrated further and
further
into the Bladder, and by degrees
lifted
up the ſides and diſplay'd its folds,
till
at length it ſeem'd to have blown it
1up to its full extent: whereupon the ex­
ternal
Air, being permitted to flow back
into
the Reciver, repulſ'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
ſevering it from the Glaſs, we did by
a
hole made at the top of the Bladder fill
the
Veſſel they both made up with Wa­
ter
, whoſe 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 moſt extend­
ed
the Bladder, it poſſeſſ'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
ſticking
together of its ſides did ſome­
what
reſiſt its expanſion: And which was
more
conſiderable, the Bladder appear'd
tumid
enough, whilſt yet a pretty deal of
Air
was left in the Receiver, whoſe ex­
ſuction
would, according to our former
Obſervation
, probably have given way
to
a further expanſion of the Air, eſpeci-
1ally ſuppoſing the dilatation not to be re­
ſtrain
'd by the Bladder.
SInce we wrote the other day the former
Experiment
, we have met with ſome
Glaſſes
not very unfit for our purpoſe;
by
means of which we are now able, with
a
little more trouble, to meaſure the ex­
panſion
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
moſt
diſtention.
We took then firſt a Cylindrical Pipe
of
Glaſs, whoſe bore was about a quarter
of
an Inch in Diameter: this Pipe was ſo
bent
and doubled, that, notwithſtanding
its
being about two foot in length, it
might
have been ſhut up into a ſmall Re­
ceiver
, not a Foot high: But by miſ­
fortune
it crack'd in the cooling, whereby
we
were reduced to make uſe of one part
which
was ſtraight and intire, but exceed­
ed
not ſix or ſeven Inches.
This little
Tube
was open at one end; and at the
other
, where it was Hermetically ſeal'd,
had
a ſmall Glaſs bubble to receive the
Air
whoſe dilatation was to be meaſur'd.
1
Along the ſide of this Tube was paſt­
ed
a ſtraight narrow piece of Parchment,
divided
into twenty ſix equal parts, mark­
ed
with black Lines and Figures, that by
them
might be meaſur'd both the inclu­
ded
Air and its dilatation.
Afterwards
we
fill'd the Tube with Water almoſt to
the
top, and ſtopping the open end with
a
Finger, and inverting the Tube, the
Air
was permitted to aſcend to the above­
mention
'd Glaſs bubble.
And by rea­
ſon
this aſcent was very ſlow, it gave us
the
opportunity to mark how much more
or
leſs then one of the twenty ſix diviſi­
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 Glaſs a bubble of
Air
equal enough, as to ſight, to one
of
thoſe Diviſions: Then the open end
of
the Tube being put into a ſmall Viol,
whoſe
bottom was cover'd with Water
about
half an Inch high; we included
both
Glaſſes into a ſmall and ſlender Re­
ceiver
, and cauſed the Pump to be ſet
work
.
The event was, That at the firſt
exſuction
of the Air there appear'd not
any
expanſion of the bubble, comparable
to
what appear'd at the ſecond, and that
upon
a very few exſuctions the bubble
1reaching as low as the ſurface of the ſub­
jacent
Water, gave us cauſe to think
that
if our Pipe had not been broken it
would
have expanded it ſelf much fur­
ther
: Wherefore we took out the little
Tube
, and found that beſides the twenty
ſix
diviſions formerly mention'd, the
Glaſs
bubble and ſome part of the Pipe
to
which the divided Parchment did not
reach
, amounted to ſix diviſions more.
Whereby it appears that the air had taken
up
one and thirty times as much room as
before
, and yet ſeem'd capable of a much
greater
expanſion, if the Glaſs would
have
permitted it.
Wherefore, after the
former
manner, we let in another bubble,
that
by our gueſs was but half as big as
the
former, and found, that upon the ex­
ſuction
of the Air from the Receiver, this
little
bubble did not onely fill up the
whole
Tube, but (in part) break through
the
ſubjacent Water in the Viol, and
thereby
manifeſt it ſelf to have poſſeſſed
ſixty
and odde times its former room.
Theſe two Experiments are mention'd
to
make way for the more eaſie belief of
that
which is now to follow.
Finding
then
that our Tube was too ſhort to ſerve
our
turn, we took a ſlender Quill of Glaſs
1which happen'd to be at hand, though it
were
not ſo fit for our purpoſe as we
could
have wiſhed, in regard it was three
or
four times as big at one end as the
ther
.
This Pipe which was thirty Inches
long
, being Hermetically ſeal'd at the
ſlender
end, was almoſt 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 ſmall hole
purpoſely
made in it for the Glaſs Pipe to
ſtand
out at, was cemented on to the Re­
ceiver
, and the Pump being ſet awork,
after
ſome exſuctions, not onely the Air
manifeſtly
appear'd extended below the
ſurface
of the ſubjacent Water; but one
of
the By-ſtanders affirms, that he ſaw
ſome
bubbles come out at the bottom of
the
Pipe and break through the Water
This
done, we left off Pumping, and ob­
ſerv
'd how at the unperceiv'd leaks of the
Receiver
the Air got in ſo faſt, thatit
very
quickly impell'd up the Water to
the
top of the Tube, excepting a little
ſpace
whereinto that bubble was repulſ'd,
which
had ſo lately poſſeſſ'd the whole
Tube
; this Air at the ſlender end ap-
1pear'd to be a Cylinder of 5/6 parts of an
Inch
in length; but when the Pipe was
taken
out and turn'd upſide down, it ap­
pear
'd at the other end inferior in bulk to a
Pea
.
Theſe things being thus done we took
(to make the Experiment the more ex­
actly
) a ſmall pair of Scales, ſuch as Gold­
Smiths
uſe 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 ſerv'd to fill up the
Tube
, wherein before we had left as much
ſpace
unfill'd up as was poſſeſſ'd by the
bubble
; and weighing again the Pipe and
Water
, we found the weight increaſ'd
onely
by one Grain.
Laſtly, pouring out
the
Water, and carefully freeing the Pipe
from
it (which yet we could not perfectly
doe
) we weighed the Glaſs 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 ἐλιτὴρ
was
ſo rarified, as to take up one hundred
fifty
two times as much room as it did be­
fore
: though it were then compreſſ'd by
1nothing but the ordinary preſſure of the
contiguous
Air.
I know not whether it
be
requiſite to take notice, that this Ex­
periment
was made indeed in a moiſt
Night
, but in a Room, in whoſe Chim­
ney
there was burning a good Fire, which
did
perhaps ſomewhat rarifie the Air of
which
the bubble conſiſted.
It has ſeem'd almoſt incredible which is
related
by the Induſtrious Merſennus, That
the
Air by the violence of heat, though
as
great as our Veſſels can ſupport with­
out
fuſion, can be ſo dilated as to take up
ſeventy
times as much room as before:
Wherefore
becauſe we were willing to
have
a confirmation of ſo ſtrange a Phæno­
menon
; we once more convey'd into the
Tube
a bubble of the bigneſs of the for­
mer
, and proſecuting the Experiment as
before
with the ſame Water, we obſerved
that
the Air did manifeſtly ſtretch it ſelf
ſo
far, as to appear ſeveral times a good
way
below the ſurface of the Water in the
Viol
, and that too with a ſurface very
convex
toward the bottom of the Pipe.
Nay, the Pump being ply'd a little lon­
ger
, the Air did manifeſtly reach to that
place
where the bottom of the Tube
lean
'd upon the bottom of the Viol, and
1ſeem'd to knock upon it and rebound
from
it: Which Circumſtances we adde,
partly
that the Phænomenon we have been
relating
may not be imputed to the
bare
ſubſiding of the Water that fill'd
the
Tube, upon the taking off the preſ­
ſure
of the ambient Air.
And partly al­
ſo
that it may appear that if our Expe­
riments
have not been as accurately made
as
with fitter Inſtruments might perhaps
be
poſſible; yet the expanſion of the
Air
is likely to be rather greater then
leſſer
then we have made it: Since the
Air
was able to preſs away the Water at
the
bottom of the Pipe, though that were
about
two Inches below the ſurface of the
Water
that was then in the Viol, and
would
have been at leaſt as high in the
Pipe
, if the Water had onely ſubſided and
not
been depreſſed: So that it ſeems not
unlikely
that if the Experiment could be
ſo
made, as that the expanſion of the Air
might
not be reſiſted by the Neighboring
Bodies
, it would yet inlarge its bounds,
and
perhaps ſtretch it ſelf to two hundred
times
its former bulk, if not more.
How­
ever
, what we have now try'd will, I hope,
ſuffice
to hinder divers of the Phænomena
of
our Engine from being diſtruſted:
1Since in that part of the Atmoſphere we
live
in, that which we call the free Air (and
preſume
to be ſo uncompreſſ'd) is crouded
into
ſo very ſmall a part of that ſpace,
which
if it were not hindred it would poſ­
ſeſs
.
We would gladly have tryed alſo
whether
the Air at its greateſt expanſion
could
be further rarified by heat; but do
what
we could, our Receiver leak'd too
faſt
to let us give our ſelves any ſatisfacti­
on
in that particular.
TO diſcover likewiſe by the means of

that
preſſure of the Air, both the
ſtrength
of Glaſs, and how much inte­
reſt
the Figure of a Body may have in its
greater
or leſſer Reſiſtance to the preſſure
of
other Bodys, we made theſe further
tryals
.
Experi­
ment
7.
We cauſ'd to be blown with a Lamp a
round
Glaſs bubble, capable of contain­
ing
, by gueſs, about five Ounces of Wa­
ter
, with a ſlender neck about the bigneſs
of
a Swans Quill, and it was purpoſely
blown
very thin, as Viols made with
Lamps
are wont to be, that the thinneſs
of
the matter might keep the roundneſs
of
the Figure from making the Veſſel too
1ſtrong. Then having moderately empty­
ed
the Receiver, and taken it out of the
Pump
, we ſpeedily applyed to the Ori­
fice
of the bottom of it the Neck of the
newly
mention'd Glaſs, carefully ſtopping
the
Crannys with melted Plaiſter, that no
Air
might get in at them: And after
turning
the Key of the Stop-cock, we
made
a free paſſage for the Air to paſs out
of
the bubble into the Receiver: which it
did
with great celerity, leaving the bub­
ble
as empty as the Receiver it ſelf; as ap­
pear
'd to us by ſome Circumſtances not
now
to be inſiſted on.
Notwithſtanding
all
which, the Veſſel, continuing as intire
as
before, gave us cauſe to wonder that
the
bare Roundneſs of the Figure ſhould
inable
a Glaſs, almoſt as thin as Paper, to
reſiſt
ſo great a preſſure as that of the
whole
incumbent Atmoſphere.
And ha­
ving
reiterated the Experiment, we found
again
that the preſſure of the ambient
Body
, thruſting all the parts inwards,
made
them, by reaſon of their arched Fi­
gure
, ſo ſupport one another, that the
Glaſs
remain'd as whole as at firſt.
Now that the Figure of the Glaſs is
of
great moment in this matter, may be
evinced
by this other Experiment.
1
WE took a Glaſs Helmet or Alem­

bick
(delineated by the ſeventh
Figure
) ſuch as Chymiſts uſe in Diſtilla­
tions
, and containing by conjecture be­
tween
two and three Pints: The Roſtrum
or
Noſe of it mark'd with (c) was Herme­
tically
cloſed; and at the top of it was a
hole
, into which was fitted and cemented
one
of the Shanks of a middle-ſiz'd Stop­
cock
; ſo that the Glaſs being turn'd up­
ſide-down
, the wide Orifice (which in
common
Glaſs-Helmets is the onely one)
was
upwards; and to that wide Orifice
was
fitted a caſt-Cover of Lead, which
was
carefully cemented on to the Glaſs:
Then
the other Shank of the Stop-cock
being
with Cement likewiſe faſten'd into
the
upper part of the Pump, the exſucti­
on
of the Air was endeavoured.
But it
was
not long before, the remaining Air
being
made much too weak to ballance
the
preſſure of the ambient Air, the Glaſs
was
not without a great noiſe crack'd al­
moſt
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 (ab); and upon an
1endeavour to pump out more of the Air,
the
crack once began, appear'd to run on
further
; though the Glaſs where it was
broken
ſeem'd to be by conjecture above
ten
, ſome thought above twenty times as
thick
as the bubble mention'd in the fore­
going
Experiment.
Experi­
ment
8.
This will perhaps make it ſeem ſtrange,
that
having taken another Glaſs bubble
blown
at the ſame time, and like for
ought
we diſcern'd for ſize, thickneſs
and
Figure to that thin one formerly
mention
'd; and having ſeal'd it up Her­
metically
, and ſuſpended it in the Recei­
ver
, the exſuction of the ambient Air did
not
enable the impriſoned Air to break, or
in
the leaſt to crack the bubble; though
the
Experiment were laboriouſly try'd,
and
that ſeveral times with bubbles of
ther
ſizes: But that perhaps the heat of
the
Candle or Lamp wherewith ſuch
Glaſſes
are Hermetically ſeal'd, (not to
mention
the warmth of his hands that
ſeal
'd it) might ſo rarifie the contained
Air
, as much to weaken its Spring, may
ſeem
probable by the following Expe­
riments
.
1
WE took a Glaſs Viol able to hold

three
or four Ounces of Water,
and
of the thickneſs uſual in Glaſſes of
that
ſize; into the Neck of this was put
a
moderately ſlender Pipe of Glaſs, which
was
carefully faſten'd with a mixture of
qual
parts of Pitch and Roſin to the Neck
of
the Viol, and which reach'd almoſt to
the
bottom of it, as the ſixth Figure de­
clares
.
Experi­
ment
9.
This Viol being upon a particular de­
ſign
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 ſmall
Receivers
, (containing between a Pint
and
a Quart) in ſuch manner as that the
Glaſs
Pipe, paſſing through a hole made
purpoſely
for it in the Leaden-Cover of
the
Receiver, was for the moſt part of it
without
the Veſſel, which being exactly
cloſed
, the Pump was ſet awork: But at
the
very firſt exſuction, and before the
Sucker
was drawn to the bottom of the
Cylinder
, there flew out of the Viol a
piece
of Glaſs half as broad as the Palm
of
a Mans Hand, and it was thrown out
with
ſuch violence, that hitting againſt
1the Neighboring ſide of the Receiver, it
not
onely dafh'd it ſelf to pieces, but
crack
'd the very Receiver in many places,
with
a great noiſe that much ſurpriſed all
that
were in the Room.
But it ſeem'd
that
in ſo little a Receiver, the Air about
the
Viol being ſuddenly drawn out, the
Air
Impriſon'd in the Veſſel, having on
it
the whole preſſure of the Atmoſphere
(to which by the Pipe open at both ends,
It
and the Water were expoſ'd) and not
having
on the other ſide the wonted preſ­
ſure
of the Ambient Air to ballance that
other
preſſure, the reſiſtance of the Glaſs
was
finally ſurmounted, and the Viol once
beginning
to break where it was weakeſt,
the
external Air might ruſh in with vio­
lence
enough to throw the crack'd parcel
ſo
forcibly againſt the Neighboring ſide
of
the Receiver, as to break that too.
And this may be preſumed ſufficient to
verifie
what we delivered in that part of
our
Appendix to the firſt Experiment,
where
we mention'd the almoſt equal
preſſure
of the Air on either ſide of a
thin
Glaſs Veſſel, as the cauſe of its not
being
broken by the forcible Spring of
the
contain'd Air.
But yet that it be not
ſuſpected
that chance had an intereſt in ſo
1odde an Experiment as we have been Re­
lating
, we will adde that for farther ſatiſ­
faction
we reiterated it in a round Glaſſe
containing
by gueſſe about ſix ounces
of
water: this violl we put into ſuch a
ſmall
Receiver as was lately mention'd,
in
ſuch manner as that the bottome of
it
reſted upon the lower part of the Pneu­
maticall
Glaſſe, and the Neck came out
through
the Leaden-Cover of the ſame
at
a hole made purpoſely for it.
But be­
ing
made circumſpect by the foregoing
miſchance
, we had put the violl into a
Bladder
, before we put it into the Re­
ceiver
to hinder this laſt named Glaſſe
from
being endanger'd by the breaking
of
the other.
Then the Pneumaticall
veſſell
being clos'd ſo that no way was
left
for the outward Air to get into it,
but
by breaking through the Viol, into
whoſe
cavity it had free acceſſe by the
mouth
of it, (which was purpoſely left
open
,) the Sucker being nimbly drawn
down
, the external Air immediatly preſſ'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 Glaſs,
was
depreſſ'd, and thruſt into it ſo vio-
1lently by the incumbent Air, that get­
ting
a little within the tapering Lip of the
Glaſs
, it did like a kinde of Wedge, thruſt
out
that ſide where it was depreſſ'd, ſo as,
though
the Receiver was new, to ſplit it.
This accident being thus mention'd upon
the
by to confirm what we formerly ſaid
touching
the fitneſs or unfitneſs of Glaſſes
of
ſome Figures to reſiſt the preſſure of
the
Atmoſphere; We will proceed to
relate
the remaining part of the Experi­
ment
, namely, That having fitted on a
wider
Cover to the ſame Receiver, and
cloſed
both that and the crack with Ce­
ment
, we proſecuted the Experiment in
the
manner above related, with this ſuc­
ceſs
: That upon the quick depreſſing of
the
Sucker, the external Air burſt the
Body
of the Viol in above a hundred pie­
ces
, many of them exceeding ſmall, and
that
with ſuch violence that we found a
wide
rent, beſides many holes, made in
the
Bladder it ſelf.
And to evince that theſe Phænomena
were
the effects of a limited and even
moderate
force, and not of ſuch an ab­
horrency
of a Vacuum as that to avoid it,
many
have been pleaſed to think that Na­
ture
muſt, upon occaſion, exerciſe an al-
1moſt boundleſs power; we afterwards pur­
poſely
try'd this Experiment with ſeveral
Glaſſes
ſomewhat thicker then thoſe Vi­
ols
, and found the event to verifie our con­
jecture
, that it would not ſucceed: for
the
Glaſſes were taken out as intire as they
were
put in.
And here, My Lord, I hold it not un­
fit
, upon occaſion of the mention that
has
been made of our having employ'd
ſmall
Receivers, and one of them, not­
withſtanding
its being crack'd, to annex
theſe
two Advertiſements.
Firſt then, beſides the great Pneuma­
tical
Glaſs ſo often mention'd, and the
proportionate
Stop-cock, we thought fit
to
provide our ſelves of ſome ſmall Recei­
vers
blown of Cryſtalline Glaſs, of ſeve­
rall
Shapes, and furniſhed with ſmaller
Stop-cocks
purpoſely made; and this we
did
upon hopes that when we had ſur­
mounted
the difficulties to be met with in
Cementing
the Glaſſes to the Stop­
cocks
, and the Pneumatical Veſſels to the
Pump
ſo exquiſitely as is requiſite for our
purpoſe
, we ſhould from the ſmalneſs of
our
Receivers receive a four-fold Advan­
tage
.
The firſt, that by reaſon of the
ſlenderneſs
of the Veſſels, and their be-
1ing made of much purer and clearer me­
tall
, as the Glaſs-men ſpeak, then the
great
Receiver, we might have a more
perfect
view of every thing happening
within
them.
The next, that ſuch ſmall
Veſſels
might be empty'd with leſs la­
bour
and in much leſſe time.
The third,
that
this nimble exſuction of the ambient
Air
would make many changes in the
Bodies
ſhut up in theſe glaſſes more ſud­
den
and conſpicuous then otherwiſe they
would
prove.
And the laſt, that we ſhould
be
able to draw and keep out the Air much
more
perfectly from ſuch ſmall Veſſels
then
from our large Receiver.
But though
we
were not much diſ-appointed in the
expectation
of the three firſt advantages,
yet
we were in our hopes of the fourth.
For beſides the great difficulty we found
in
fitting together the Glaſſes, the Stop­
cocks
and the Covers; beſides this I ſay,
we
found our ſelves ſeldom able to draw,
and
keep out the Air ſo far as to make the
remaining
Air in theſe Receivers weaker
then
the remaining Air in our great Recei­
ver
.
For though ſometimes the Leaks
of
ſome of theſe little Receivers may be
much
either fewer or ſmaller then thoſe
of
the larger Veſſel; yet a little Air get-
1ting into one of theſe, wherein it had but
little
room to expand and diſplay it ſelf,
might
preſs as much upon all parts of the
internal
ſurface of the Veſſel, and upon
the
included Bodies, as a greater quan­
tity
of Air in a Veſſel in whoſe capacity
it
might finde more room to expand it
ſelf
.
The other thing that we were to ad­
vertiſe
, is, That 'tis not every ſmall crack
that
can make ſuch a Receiver as is of a
roundiſh
Figure altogether uſeleſs to our
Experiment
, in regard that upon the ex­
ſuction
of the internal Air, the ambient
Air
on all ſides preſſing the Glaſs inwards
or
towards the middle, does conſequent­
ly
thruſt the Lips of the crack cloſer, and
ſo
rather cloſe then increaſe it.
This I mention partly becauſe Recei­
vers
fit for our turn are more eaſily
crack
'd then procur'd, and therefore ought
not
to be unneceſſarily thrown away as
unſerviceable
: And partly becauſe I think
it
becomes one that profeſſes himſelf a
faithful
Relator of Experiments, not to
conceal
from Your Lordſhip, 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-
1ning at the upper Orifice, and occaſion'd,
as
it ſeem'd, by the exceſſive 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 Plaiſter,
which
in one of our Eſſays written ſome
years
ſince to your ingenious and hopeful
Couſin
Fones, we extoll for the mending
of
crack'd Receivers, and other Chymi­
cal
Glaſſes; and having afterwards thick­
ly
over-laid this Plaiſter with Diachylon,
we
neither could then, nor can yet per­
ceive
that the Veſſel leaks ſenſibly at that
crack
.
The Plaiſter was made of good quick
Lime
finely poudred, and nimbly ground
with
a Peſtle in a Morter, with a quantity
(I know not how much preciſely, not ha­
ving
thoſe Eſſays in this place) of ſcra­
pings
of Cheeſe and a little fair Water,
no
more then is juſt neceſſary to bring the
mixture
to a ſomewhat ſoft Paſte, which
when
the Ingredients are exquiſitely in­
corporated
, will have a ſtrong and
ſtincking
ſmell: Then it muſt be im­
mediately
ſpread upon a Linnen Cloath
three
or four fingers breadth, and preſently
apply
'd, leſt it begin to harden.
But if
Your
Lordſhip had ſeen how we mended
1with it Receivers even for the moſt ſub­
tle
Chymical Spirits, You would ſcarce
wonder
at the ſervice it has done in our
Pneumatical
Glaſs.
WE took a Tallow-Candle of ſuch

a
ſize that eight of them make
about
a pound, and having in a very com­
modious
Candleſtick let it down into the
Receiver
, and ſo ſuſpended it that the
Flame
burnt almoſt in the middle of the
Veſſel
, we did in ſome two minutes ex­
actly
cloſe 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
purpoſely
left of that length we judged
the
moſt convenient for the laſting of
the
Flame.
Experi­
ment
10.
But the ſecond time having put in the
ſame
Candle into the Receiver, (after it
had
by the blaſts of a pair of Bellows
been
freed from Fumes) the Flame laſted
about
two minutes from the time the
Pumper
began to draw out the Air; up­
on
the firſt exſuction whereof, the Flame
ſeem
'd to contract it ſelf in all its Dimen­
ſions
.
And theſe things were further ob-
1ſervable, that after the two or three firſt
exſuctions
of the Air, the Flame (except
at
the very top) appear'd exceeding blew,
and
that the Flame ſtill receded more and
more
from the Tallow, till at length it
appear
'd to poſſeſs onely the very top of
the
Week, and there it went out.
The ſame Candle being lighted again
was
ſhut into the Receiver, to try how it
would
laſt there without drawing forth
the
Air, and we found that it laſted much
longer
then formerly; and before it went
out
receded from the Tallow towards the
the
top of the Week, but not near ſo
much
as in the former Experiment.
And having an intention to obſerve par­
ticularly
what the motion of the ſmoak
would
be in theſe Experiments: We
took
notice that when the Air was not
drawn
out, there did upon the extinction
of
the Flame a conſiderable part of the
Week
remain kindled, which (probably
by
reaſon of the Circulation of the Air
in
the Veſſel, occaſion'd by the heat)
mitted
a Steam, which aſcended ſwiftly
and
directly upwards in a ſlender and unin­
terrupted
Cylinder of ſmoke, till it came
to
the top, whence it manifeſtly recoyl'd
by
the ſides to the lower part of the Veſ-
1ſel. Whereas when the Flame went out
upon
the exſuction of the Air one time
(when the Flame retir'd very leaſurely
to
the top) we perceived it not to be fol­
low
'd by any ſmoke at all.
And at an
other
time the upper part of the Week
remaining
kindled after the extinction
of
the Flame, the ſlender ſteam of Fumes
that
did ariſe aſcended but a very little
way
, and then after ſome uncertain mo­
tions
this and that way, did, for the moſt
part
, ſoon fall downwards.
Being deſirous alſo to try whether
there
would be any difference as well in
our
Receiver as there is wont to be elſe­
where
betwixt Candles made of Wax and
thoſe
made of Tallow, as to their dura­
tion
; we took ſlender Tapers of white
Wax
, (commonly called Virgins Wax)
that
being found to burn with much leſs
ſmoke
then common yellow Wax: Six
of
theſe of like bigneſs, and each of them
of
about the thickneſs of a Swans Quill,
we
preſſ'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 haſte we could to
cloſe
it up with Cement.
But though in
the
mean while we left open the Valve
1of the Cylinder, the hole of the Stop­
cock
and that in the Cover of the Re­
ceiver
, that ſome Air might get in to
cheriſh
the Flame and the ſmoke might
have
a vent; Yet for ſo great a Flame
the
Air ſufficed not ſo much as till the
Cover
could be perfectly luted on: So
that
before we were quite ready to imploy
the
Pump, the Candle was extinguiſhed.
Wherefore we took but one of the
bove
mention'd Tapers, and having
lighted
it, cloſ'd it up in the Receiver, to
try
how long a ſmall Flame with a pro­
portionable
ſmoke would continue in
ſuch
a quantity of Air: But we found
upon
two ſeveral 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 ſwinging
of
the Wier to and fro (in the Engine
ſhaken
by pumping) haſten'd the vaniſh­
ing
of the Flame, which ſeem'd by that
motion
to be caſt ſometimes on one ſide
of
the Week and ſometimes on the
ther
; But though once we purpoſely
refrain
'd pumping after a very few ex­
ſuctions
of the Air, that the Flame might
not
be agitated, yet it laſted not much
longer
then the newly mention'd time.
1And laſtly, cloſing up the ſame Taper,
lighted
again, to diſcover how long it
would
laſt without drawing out of the
Air
, we found that it burn'd for a while
vividly
enough, but afterwards began to
be
leſſen'd more and more in all its Di­
menſions
.
And we obſerv'd that the
Flame
did not, as before, retire it ſelf by
little
and little towards the top, but to­
wards
the bottom of the Week (from
which
yet it did a little withdraw upwards
juſt
before it went out) ſo that the upper
part
of the Week appear'd for a pretty
while
manifeſtly above the top of the
Flame
, which having laſted about five
minutes
, was ſucceeded by a directly aſ­
cending
ſtream of Smoak.
THere was taken a Wier, which being

bent
almoſt in the form of a Screw,
conſtituted
ſuch an Inſtrument to contein
Coals
and leave them every way acceſſi­
ble
to the Air, as the tenth Figure de­
clares
; the breadth of this Veſſel was no
leſs
then that it might with eaſe 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
1it down into the Glaſs; and ſpeedily clo­
ſing
it, we cauſ'd the Pumper to ply
his
work, and obſerv'd that upon the ve­
ry
firſt exſuction of the Air (though per­
haps
not becauſe of that onely) the Fire
in
the Coals began to grow very dim, and
though
the agitation of the Veſſel did
make
them ſwing up and down (which in
the
free Air would have retarded the ex­
tinction
of the Fire) yet when we could
no
longer diſcern any redneſs at all in any
of
them; caſting our eyes upon a Minute­
Watch
we kept by us on this occaſion, 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 diſ-appearing of
the
Fire, there had paſſed but three mi­
nutes
.
Experi­
ment
11.
Whereupon, to try the Experiment a
little
further, we preſently took out the
Coals
, in which it ſeems there had re­
mained
ſome 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 ſeveral places, wherefore having by
ſwinging
them about in the Wier,
throughly
lighted them the ſecond time,
welet
them down again into the Receiver,
1and cloſ'd it ſpeedily as before; and then
waiting
till the Fire ſeem'd totally ex­
tinct
without medling with the Pump, we
found
that from the time the Veſſel was
cloſ
'd till that no Fire at all could be per­
ceiv
'd there had paſſed about four mi­
nutes
: Whereby it ſeem'd to appear that
the
drawing away of the ambient Air
made
the Fire go out ſooner then other­
wiſe
it would have done; though that part
of
the Air that we drew out left the more
room
for the ſtifling ſteams of the Coals
to
be received into.
Laſtly, Having taken out the Wier
and
put other Coals into it, we did, in the
ſame
Room where the Engine ſtood, let it
hang
quietly by a ſtring in the open Air,
to
try how long the Fire would laſt with­
out
agitation when no Air was kept from
it
.
And we found that the Fire began to
go
out firſt at the top and out-ſides of the
Coals
; but inwards and near the bottom
the
Fire continu'd viſible for above half
an
hour, a great part of the Coals, eſpe­
cially
thoſe next the bottom, being burnt
to
aſhes before the Fire went out.
We cauſ'd likewiſe a piece of Iron to
be
forg'd, of the bigneſs of a middle ſiz'd
Char-coal
, and having made it red hot
1throughout; we cauſ'd it in the lately
mention
'd Wier, to be ſpeedily convey'd
and
ſhut up into the Receiver, being de­
ſirous
to try what would become of a
glowing
Body, by reaſon of its texture
more
vehemently hot then a burning
Coal
of the ſame bigneſs, & yet unlike to
ſend
forth ſuch copious & ſtifling Fumes:
But
we could not obſerve any manifeſt
change
upon the exſuction of the Air.
The Iron began indeed to loſe its Fiery
redneſs
at the top, but that ſeem'd to be
becauſe
it was it the upper end ſomewhat
more
ſlender then at the lower: The red­
neſs
, though it were in the day time, con­
tinued
viſible about four minutes; and
then
, before it did quite diſ-appear, we
turn
'd the Key of the Stop-cock but
could
not diſcern any change of the Iron
upon
the ruſhing in of the Air.
Yet ſome
little
remainders of Wax that ſtuck to
the
Wier, and were turn'd into Fumes by
the
heat of the neighboring Iron, ſeem'd
to
afford a more plentiful, or at leaſt a
much
more free expanded ſmoke when
the
Air was ſuck'd out, then afterwards;
though
allowance was made for the de­
creaſing
heat of the Iron.
And laſtly,
notwithſtanding
a conſiderable exſuction
1of the ambient Air, though not by far ſo
great
a one as might have been made by
the
Engine; and notwithſtanding the in­
conſiderable
diſſipation of the parts of the
Iron
, the ſurrounding ſides of the Recei­
ver
were ſenſibly, and almoſt offenſively
heated
by it; inſomuch that a pretty while
after
the Iron was taken out, the ſides of
the
Glaſs manifeſtly retain'd a warmth:
which
would not be unfit to be conſider'd
by
a Perſon at more leaſure then I am
now
.
BEing willing to try after this ſome­

thing
that would not cheriſh much
Fire
at once, and would keep Fire much
longer
then a Coal.
We took a piece of
Match
, ſuch as Souldiers uſe, of the thick­
neſs
of a Mans little Finger, or ſomewhat
thicker
; and this being well lighted at
one
end, was by a ſtring ſuſpended with
that
end downwards in the cavity of the
Receiver
which was immediately cloſ'd:
And
yet by that time it could well be ſo,
the
copious Fumes of the Match had neer
fill
'd and darken'd the Receiver.
Where­
fore
, leſt the Veſſel ſhould be endanger'd,
the
Pump was nimbly ply'd, and a great
1deal of Air and Smoke mixt together was
drawn
out, whereby the Receiver grow­
ing
more clear, we could diſcern the Fire
in
the Match to burn more and more lan­
guidly
: And notwithſtanding that by the
diligence
uſ'd in Pumping, it ſeem'd to
have
room enough allow'd it to throw
out
Fumes; yet after no long time it
ceaſ
'd from being diſcernable either by its
Light
or its Smoke.
And though by
that
we were invited to ſuppoſe it quite
extinguiſhed
, yet we continu'd pumping
a
while, in proſecution of another Expe­
riment
we were trying at the ſame time:
And
this we did the more willingly be­
cauſe
of a ſuſpicion the Experiment
bout
the Coals might eaſily ſuggeſt, and
which
the event declar'd not to have been
altogether
groundleſs.
For upon the
Admiſſion
of the external Air, the Fire,
that
ſeem'd to have gone out a pretty
while
before, did preſently revive; and
being
as it were refreſh d by the new Air,
and
blown by the Wind made by that
Air
in ruſhing in, it began again to ſhine
and
diſſipate the neighboring Fuel into
Smoke
as formerly.
1
Experi­
ment
12.
A While after we let down into

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)
bove
a Pint of Air, but being capable of
containing
ten or twelve times as much.
Experi­
ment
13.
Our ſcope in this Experiment was
partly
to try whether or no the ſmoke of
the
Match, repleniſhing the Receiver,
would
be able to hinder the Dilatation of
the
inward Air, upon the exſuction of the
Ambient
.
And partly to diſcover whe­
ther
the extinction of the Fire in the
Match
did proceed from want of Air, or
barely
from the preſſure of its own
Fumes
, which for want of room to ex­
pand
themſelves in, might be ſuppoſ'd
to
Recoyl upon the Fire, and ſo to
ſtifle
it.
The event of our tryal was, That
at
the beginning of our Pumping the
Match
appear'd well lighted, though
it
had almoſt fill'd the Receiver with
its
plentiful Fumes: But by degrees it
burnt
more and more dimly, notwith­
ſtanding
that by the nimble drawing
1out the Air and Smoke, the Veſſel
were
made leſs opacous, and leſs full of
compreſſing
matter; as appeard by this,
That
the longer we pump'd, the leſſer
Air
and Smoke came out of the Cylin­
der
at the opening the Valve, and conſe­
quently
the leſs came into it before; yet
the
Fire in the Match went but ſlowly
out
.
And when afterwards, to ſatisfie
our
ſelves of its expiration, we had dar­
ken
'd the Room, and in vain endeavored
to
diſcover any ſpark of Fire, as we could
not
for ſome time before by the help of
Candles
diſcern the leaſt riſing of Smoke,
we
yet continued pumping ſix or ſeven
times
; and after all that letting in the
Air
, the ſeemingly dead Fire quickly
revived
, and manifeſted its recovery by
Light
and ſtore of Smoke, with the
latter
of which it quickly began to re­
pleniſh
the Receiver.
Then we fell
to
pumping afreſh, and continued that
labour
ſo long till the re-kindled
Match
went out again: and thinking
it
then fit not to ceaſe from Pum­
ping
ſo ſoon as before, we found that
in
leſs then half a quarter of an hour the
Fire
was got out for good and all,
1and paſt the poſſibility of being recover'd
by
the re-admitted Air.
Some Circumſtances, beſides thoſe al­
ready
mention'd, occurr'd in the making
of
the Experiment, of which theſe are
the
principal.
Firſt, when the Receiver was full of
Smoke
, if the Cylinder were emptied,
immediately
upon the turning of the
Stop-cock
, the Receiver would appear
manifeſtly
darken'd to his eye that look'd
upon
the light through it: and this dark­
neſs
was much leſs when the Receiver was
much
leſs fill'd with Fumes: It was alſo
inſtantaneous
, and ſeem'd to proceed from
a
ſudden change of place and ſcituation
in
the exhalations, upon the vent ſud­
denly
afforded them and the Air they
were
mixt with, out of the Receiver into
the
Cylinder.
The next thing we obſerv'd was, a kinde
of
Halo that appear'd a good while about
the
Fire, and ſeem'd to be produced by
the
ſurrounding Exhalations.
And laſtly, it is remarkable, That even
when
the Fumes ſeemed moſt to reple­
niſh
the Receiver, they did not ſenſibly
hinder
the Air included in the Bladder
from
dilating it ſelf after the ſame manner
1(for ought we could diſcern) as it would
have
otherwiſe done: So that before the
Fire
or the Match was quite extinct, the
Bladder
appear'd ſwell'd at leaſt to ſix or
ſeven
times its former capacity.
Since the writing of theſe laſt Lines,
we
took a ſmall Receiver, capable of
containing
(by gueſs) about a pound and
a
half of Water; and in the midſt of it
we
ſuſpended 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 ſuch haſte, but that before
we
began to pump, the Smoke had ſo
fill
'd that ſmall Receiver, as for ought we
diſcern
'd, to choke the Fire.
And having
again
and again reiterated the Experi­
ment
, it ſeem'd ſtill as at firſt, that we
could
not cloſe up the Veſſel and pump
out
all the Fumes time enough to reſcue
the
Fire from Extinction; whereupon we
made
uſe of this Expedient.
Aſſoon as
we
had pump'd once or twice, we ſudden­
ly
turn'd the Key, and thereby gave acceſs
to
the excluded Air, which ruſhing vio­
lently
in, as if it had been forced thorow
a
pair of Bellows, did both drive away
the
aſhes, fill the Glaſs with freſh Air, and
1by blowing the almoſt extinguiſh'd Fire,
re-kindl
'd it, as appear'd by the Matches
beginning
again to ſmoke, which before it
had
ceaſ'd to do; we having by this
means
obtain'd a lighted Match in the
Receiver
, without being reduc'd to ſpend
time
to cloſe it up, commanded the Air
to
be immediatly pump'd out, and found
that
upon the exſuction of it, the Match
quickly
left ſmokeing, as it ſeem'd, by
reaſon
of the abſence of the Air; and
yet
if ſome urgent occaſions had not hin­
der
'd us, we would for greater ſecurity
have
try'd, whether or no the Match re­
kindled
as formerly, would ſmoke much
longer
, in caſe of no exſuction of the am­
bient
Air.
TO try diverſe things at once,

and
particularly whether Fire,
though
we found it would not long laſt,
might
not yet be produced in our eva­
cuated
Receiver: We took a Piſtol of
about
a Foot in length, and having
firmly
tyed it to a ſtick almoſt 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
1the Tricker one end of a ſtring, whoſe
other
end was faſten'd to the Key former­
ly
mention'd to belong to the Cover of
our
Receiver.
This done, we convey'd
the
Piſtol, together with the annexed
Staff
, into the Veſſel: which being cloſ'd
up
, and empty'd after the uſual man­
ner
, we began to turn the Key in the
Cover
; and thereby ſhortning the ſtring
that
reach'd from it to the Piſtol, we
pull
'd aſide the Tricker, and obſerv'd,
that
according to our expectation the
force
of the Spring of the Lock was
not
ſenſibly abated by the abſence of
the
Air. (from whoſe impetus yet ſome
Modern
Naturaliſts would derive the
cauſe
of the motion of Reſtitution in
ſolid
Bodies) For the Cock falling
with
its wonted violence upon the Steel,
ſtruck
out of it as many and as conſpi­
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 alſo obſerved
whether
or no there would appear
any
conſiderable Diverſity in the
Motion
of the ſhining Sparks in a
place
where the remaining Aire was
ſo
much rarified, but could not perceive
1but that they moved ſome of them up­
wards
, as well as ſome of them down­
wards
, and ſome of them ſide-ways, as
they
are wont to do, when upon ſuch col­
liſions
they fly out in the open Air.
Experi­
ment
14.
We likewiſe cauſ'd a piece of Steel to
be
made of the form and bigneſs of the
Flint
, in whoſe place we put it, and then
the
Piſtol 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 purpoſely ſomewhat dar­
ken
'd, yet there appear'd not upon the
ſtriking
of the two Steels againſt each
ther
the leaſt ſpark of Fire: Nor did we
expect
any (having before in vain attem­
pted
to ſtrike Fire this way in the open
Air
) though we thought fit to make the
Experiment
to undeceive thoſe who fan­
cy
in rarified Air, I know not what ſtrange
diſpoſition
, to take Fire upon a much
ſlighter
occaſion then this Experiment
afforded
.
We have indeed found, that
by
the dextrous Colliſion of two har­
den
'd pieces of Steel, ſtore of ſparks
may
be ſtruck out: But that was done with
ſuch
vehement percuſſion of the edges of
the
two Steels, as could not well be com­
paſſ
'd in our Receiver.
1
But the chief thing we deſign'd to do
with
our Piſtol, was, To obſerve whe­
ther
Gun-powder would take Fire in our
empty
'd and cloſely ſtop'd Glaſs?
Whe­
ther
the expanſion of the Flame would be
conſiderably
varied by the abſence of ſo
much
of the ambient Air as was drawn
out
of the Receiver?
and whether the
Flame
would diffuſe it ſelf upward, as it is
wont
, notwithſtanding its not having
bout
it the uſual proportion of Air to
force
it up?
And though moſt of our at­
tempts
to fire the Gun-powder in the
Pan
of the Piſtol ſucceeded not, becauſe
we
were fain to let it hang almoſt perpen­
dicular
in the Receiver; whereby the
Powder
was ſhaken down before the
ſparks
could reach it: yet once the Ex­
periment
ſucceeded, and the kindled
Powder
ſeem'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 reaſon of that
little
portion of Air, which in ſpight of
our
pumping remained in the Receiver, or
for
any other cauſe, we have not now the
leiſure
to conſider.
But we muſt not for­
get
, that upon the extinction of the Flame
the
Receiver appear'd darken'd with
1ſmoke, which ſeem'd to move freely up
and
down, and upon the letting in the Air
at
the Stop-cock began to circulate much
faſter
then before.
We wonld have made
more
obſervations concerning this Flame,
but
that of two or three attempts we
afterwards
made to repeat the kindling of
Powder
, not any one ſucceeded; and
we
have not the leaſure to dwell long up­
on
one kinde of Tryals.
TO theſe Experiments concerning Fire

we
added another, which, though it ſuc­
ceded
not, may perhaps without imper­
tinency
be recorded: partly becauſe that
(as we have in another Treatiſe amply de­
clar
'd) it is uſefull to recite what Experi­
ments
miſcarry as well as what ſucceed.
And partly alſo becauſe it is very poſſible
that
what we endeavored in vaine, may be
performed
by Your Lordſhip, or ſome
other
Virtuoſo that ſhall have ſlancker
Veſſells
then we had, and more Sunny
dayes
then the preſent Winter allows
us
.
Experi­
ment
15.
We convey'd then into one of our ſmall
Receivers
a piece of matter combuſtible,
dry
and black (experience declaring things
1of that colour to be moſt eaſily kindled)
& carefully cloſing the Veſſel we brought
it
to a Window at which the Sun, not very
faire
from the Meridian, ſhone in very free­
ly
: then drawing out the Aire with ſpeed
united
the Sun-beames with a burning
Glaſs
upon the combuſtible matter which
began
immediatly to ſend forth a Smoke
that
quickly darkned the Receiver, but
notwithſtanding
all our care and diligence
the
externall Aire got in ſo faſt that after
diverſe
tryals we were fayne to leave off
the
Experiment in that Glaſſe and induc'd
to
make tryall of it in our great Re­
ceiver
.
Haveing then after ſome difficulty
lodg
'd the combuſtible matter in the ca­
vity
of this Veſſell in ſuch manner as that
it
was almoſt contiguous to that ſide
thereof
that was next the Sun, we did en­
deavor
with a pretty large burning Glaſs
to
kindle it, but found, as we fear'd,
That
by reaſon of the thickneſs of the
Glaſs
, (which was alſo of a leſs pure and
leſs
Diaphanous matter then the
ther
) the Sun-beams thrown in by the
burning
Glaſs, were in their paſſage
ſo
Diſlocated and Scattered (not now to
mention
thoſe many that being reflected,
1I could not pierce into the cavity of the
Receiver
) that we could not poſſibly
nite
enough of them to kindle the matter,
nor
ſo much as to make it ſenſibly ſmoke.
Yet we hope that the ſeeing whether Bo­
dies
(other then Gun-powder) may be
kindled
, and what would happen to them
when
ſet on fire, in a place in great mea­
ſure
devoid of Air, may prove ſo Lucife­
rous
an Experiment, that when the Sea­
ſon
is more favorable we ſhall, God per­
mitting
, make further tryal of it, and ac­
quaint
Your Lordſhip with the Event, if
it
prove proſperous.
In the mean time
we
ſhall paſs on to other Experiments,
aſſoon
as we have advertiſ'd Your Lord­
ſhip
that we have forborn to make ſuch
Reflections
upon the ſeveral Experiments
we
have ſet down concerning Fire, as the
matter
would have eaſily enough afford­
ed
, and Your Lordſhip may perhaps have
expected
.
But I made the leſs ſcruple to
forbear
the annexing of Speculations to
theſe
Recitals, becauſe Carneades & Eleu­
therius
have in ſome Dialogues concern­
ing
Heat and Flame, which were laſt year
ſeen
by ſome Friends, and may be, when
you
pleaſe, commanded by You, men-
1tion'd divers of my Thoughts and Expe­
riments
concerning Fire.
WE deſigned to try whether or no

divers
Magnetical Experiments
would
exhibit any unuſual Phænomena,
being
made in our Evacuated Receiver
inſtead
of the open Air: But for want of
leiſure
and conveniency to proſecute ſuch
Tryals
, we were induced to reſerve the
reſt
for an other time, and to content our
ſelves
with making that which follows.
We convey'd into the Receiver a little
Pedeſtal
of Wood, in the midſt of which
was
perpendicularly erected a ſlender
Iron
, upon whoſe ſharp point an excited
Needle
of Steel purpoſely made, and of
about
five Inches long, was ſo placed
that
hanging in an Æquilibrium it could
move
freely towards either hand.
Then
the
Air being after the uſual manner
pumped
out, we apply'd a Load-ſtone
moderately
vigorous to the out-ſide of
of
the Glaſs, 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
ſame
Load-ſtone would have done had
1none of the Air been drawn away from
bout
the Needle, which when the Load­
ſtone
was removed, after ſome tremu­
lous
Vibrations to and fro, reſted in a po­
ſition
wherein it look'd North and
South
.
Experi­
ment
16
PRoceed we now to the mention of

that
Experiment, whereof the ſatiſ­
factory
tryal was the principal Fruit I
promiſ
'd my ſelf from our Engine.
It
being
then ſufficiently known, that, in
the
Experiment De Vacuo, the Quick­
ſilver
in the Tube is wont to remain ele­
vated
, above the ſurface of that whereon
it
leans, about 27 digits: I conſidered,
that
, if the true and onely reaſon why the
Quick-ſilver
falls no lower, be, that at
that
Altitude, the Mercurial Cylinder in
the
Tube, is an Æquilibrium with the
Cylinder
of Air, ſuppoſ'd to reach from
the
adjacent Mercury to the top of the
Atmoſphere
: If this Experiment could
be
try'd out of the Atmoſphere, the
Quick-ſilver
in the Tube would fall
down
to a levell with that in the Veſſel,
ſince
then there would be no preſſure up­
on
the Subjacent, to reſiſt the weight of
1the Incumbent Mercury. Whence I in­
ferr
'd (as eaſily I might) that, if the Ex­
periment
could be try'd in our Engine, the
Quick-ſilver
would ſubſide below 27 Di­
gits
, in proportion to the exſuction of
Air
, that ſhould be made out of the Re­
ceiver
.
For, as when the Air is ſhut in­
to
the Receiver, it does (according to
what
hath above been taught) continue
there
as ſtrongly compreſſ'd, as it did
whil
'ſt all the incumbent Cylinder of the
Atmoſphere
lean'd immediatly upon it;
becauſe
the Glaſs, wherein it is pent up,
hinders
it to deliver it ſelf, by an expanſi­
on
of its parts, from the preſſure where­
with
it was ſhut up.
So, if we could per­
fectly
draw the Air out of the Receiver,
it
would conduce as well to our purpoſe,
as
if we were allow'd to try the Experi­
ment
beyond the Atmoſphere.
Experi­
ment
17.
Wherefore (after having ſurmounted
ſome
little difficulties which occurr'd at
the
beginning) the Experiment was made
after
this manner.
We took a ſlender and
very
curiouſly blown Cylinder of Glaſs,
of
near three Foot in length, and whoſe
bore
had in Diameter a quarter of an Inch,
wanting
a hairs breadth: This Pipe being
Hermetically
ſeal'd at one end, was, at
1the other, fill'd with Quick-ſilver, care
being
taken in the filling, that as few
bubles
as was poſſible ſhould be left in the
Mercury
: Then the Tube being ſtopt
with
the Finger and inverted, was open'd,
according
to the manner of the Experi­
ment
, into a ſomewhat long and ſlender
Cylindrical
Box (inſtead of which we now
are
wont to uſe a Glaſs of the ſame form)
half
fill'd with Quick-ſilver: And ſo, the
liquid
metal being ſuffered to ſubſide, and
a
piece of Paper being paſted on levell
with
its upper ſurface, the Box and Tube
and
all were by ſtrings carefully let down
into
the Receiver, and then, by means of
the
hole formerly mention'd to be left in
the
Cover, the ſaid Cover was ſlip't along
as
much of the Tube as reach'd above the
top
of the Receiver; And the Interval,
left
betwixt the ſides of the Hole and
thoſe
of the Tube, was very exquiſitely
fill
'd up with melted (but not over hot)
Diachylon
; and the round chink, betwixt
the
Cover and the Receiver, was likewiſe
very
carefully cloſ'd up: Upon which clo­
ſure
there appear'd not any change in the
height
of the Mercurial Cylinder; no
more
, then if the interpoſ'd Glaſs Recei­
ver
did not hinder the immediate preſſure
1of the ambient Atmoſphere upon the
incloſed
Air; which hereby appears to
bear
up on the Mercury, rather by virtue
of
its ſpring, then of its weight: ſince its
weight
cannot be ſuppoſ'd to amount to
above
two or three Ounces, which is in­
conſiderable
in compariſon of ſuch a Cy­
linder
of Mercury as it would keep from
ſubſiding
.
All things being thus in a readineſs, the
Sucker
was drawn down; and, immedi­
ately
upon the egreſs of a Cylinder of
Air
out of the Receiver; the Quick-ſilver
in
the Tube did, according to expectati­
on
, ſubſide: and notice being carefully
taken
(by a mark faſten'd to the outſide)
of
the place where it ſtopt, we cauſ'd him
that
manag'd the Pump to pump again,
and
mark'd how low the Quick-ſilver fell
at
the ſecond exſuction; but continuing
this
work, we were quickly hindred from
accurately
marking the Stages made by
the
Mercury in its deſcent, becauſe it ſoon
ſunk
below the top of the Receiver; ſo
that
we could thenceforward mark it no
other
ways then by the eye.
And thus,
continuing
the labor of pumping for
bout
a quarter of an hour, we found our
ſelves
unable to bring the Quick-ſilver in
1the Tube totally to ſubſide; becauſe,
when
the Receiver was conſiderably em­
pty
'd of its Air, and conſequently that
little
that remain'd grown unable to reſiſt
the
Irruption of the external, that Air
would
(in ſpight of whatever we could
do
) preſs in at ſome little Avenue or
other
; and though much could not there­
at
get in, yet a little was ſufficient to coun­
terballance
the preſſure of ſo ſmall a Cy­
linder
of Quick-ſilver, as then remain'd
in
the Tube.
Now (to ſatisfie our ſelves further, that
the
failing of the Quick-ſilver in the
Tube
to a determinate height, proceeds
from
the Æquilibrium, wherein it is at
that
height with the external Air, the one
gravitating
, the other preſſing with equal
force
upon the ſubjacent Mercury) we Re­
turned
the Key and let in ſome new Air;
upon
which the Mercury immediatly be­
gan
to aſcend (or rather to be impell'd up­
wards
) in the Tube, and continu'd aſcend­
ing
, till having Return'd the Key it im­
mediatly
reſted at the height which it had
then
attain'd: And ſo, by Turning and
Returning
the Key, we did ſeveral times
at
pleaſure impel it upwards, and check its
aſcent
.
And laſtly, having given a free
1egreſs at the Stop-cock to as much of the
external
Air as would come in, the Quick­
ſilver
was impell'd up almoſt to its firſt
height
: I ſay almoſt, becauſe it ſtopt
near
a quarter of an Inch beneath the Pa­
per
mark formerly mention'd; which we
aſcrib
'd to this, That there was (as is
ſual
in this Experiment) ſome little Parti­
cles
of Air engag'd among thoſe of the
Quick-ſilver
; which Particles, upon the
deſcent
of the Quick-ſilver, did manifeſt­
ly
riſe up in Bubbles towards the top of
the
Tube, and by their preſſure, as well
as
by leſſening the Cylinder by as much
room
as they formerly took up in it, hin­
der
'd the Quick-ſilver from regaining its
firſt
height.
This Experiment was a few days after
repeated
in the preſence of thoſe excellent
and
deſervedly Famous Mathematick
Profeſſors
, Dr. Wallis, Dr. Ward, and Mr.
Wren, who were pleaſed to Honor it with
their
Preſence: And whom I name, both
as
juſtly counting it an Honor to be
known
to them, and as being glad of ſuch
Judicious
and illuſtrious Witneſſes of our
Experiment
; and 'twas by their gueſs that
the
top of the Quick-ſilver in the Tube
was
defin'd to be brought within an Inch
1of the ſurface of that in the Veſſel.
And here, for the Illuſtration of the
foregoing
Experiment, it will not be
miſs
to mention ſome other particulars
relating
to it.
Firſt then, When we endeavor'd to
make
the Experiment with the Tube
cloſ
'd at one end with Diachylon inſtead
of
an Hermetical Seal; we perceiv'd, that
upon
the drawing of ſome of the Air out
of
the Receiver, the Mercury did indeed
begin
to fall, but continu'd afterwards to
ſubſide
, though we did not continue pum­
ping
.
Whence it appear'd, that though
the
Diachylon that ſtopt the end of the
Tube
were ſo thick and ſtrong, that the
external
Air could not preſs it in (as expe­
rience
taught us that it would have done,
if
there had been but little of it) yet the
ſubt
'ler parts of it were able (though
ſlowly
) to inſinuate themſelves through
the
very body of the Plaiſter, which it
ſeems
was of ſo cloſe a Texture, as that
which
we mention'd our ſelves to have
ſucceſsfully
made uſe of in the Experi­
ment
De Vacuo ſome years ago. So that
now
we begin to ſuſpect, that perhaps one
Reaſon
, why we cannot perfectly pump
out
the Air, may be, that when the Veſſel
1is almoſt empty, ſome of the ſubtler
parts
of the external Air may, by the
preſſure
of the Atmoſphere, be ſtrain'd
through
the very body of the Diachylon
into
the Receiver.
But this is onely con­
jecture
:
Another Circumſtance of our Expe­
riment
was this, That, if (when the
Quick-ſilver
in the Tube was fallen low)
too
much ingreſs were, at the hole of the
Stop-cock
, ſuddenly permitted to the ex­
ternal
Air; it would ruſh in with that vio­
lence
, and bear ſo forcibly upon the ſur­
face
of the ſubjacent Quick-ſilver, that
it
would impel it up into the Tube rudely
enough
to endanger the breaking of the
Glaſs
.
We formerly mention'd, that the
Quick-ſilver
did not in its deſcent fall as
much
at a time after the two or three firſt
exſuctions
of the Air, as at the beginning:
For
, having mark'd its ſeveral Stages up­
on
the Tube, we found, that at the firſt
ſuck
it deſcended an Inch and 3/8, and at the
ſecond
an Inch and 1/8; and when the Veſ­
ſel
was almoſt empty'd, it would ſcarce at
one
exſuction be drawn down above the
breadth
of a Barly-corn.
And indeed we
found
it very difficult to meaſure in what
1proportion theſe decrements of the Mer­
curial
Cylinder did proceed: partly be­
cauſe
(as we have already intimated) the
Quick
ſilver was ſoon drawn below the
top
of the Receiver: and partly becauſe,
upon
its deſcent at each exſuction, it
would
immediatly reaſcend a little up­
wards
; either by reaſon of the leaking of
the
Veſſel at ſome imperceptible hole or
other
, or by reaſon of the motion of
Reſtitution
in the Air, which, being ſome­
what
compreſt by the fall as well as weight
of
the Quick ſilver, would repell it a lit­
tle
upwards, and make it vibrate a little up
and
down, before they could reduce each
other
to ſuch an Æquilibrium as both
might
reſt in.
But though we could not
hitherto
make obſervations accurate
nough
concerning the meaſures of the
Quick-ſilver
's deſcent, to reduce them in­
to
any Hypotheſis, yet would we not diſ­
courage
any from attempting it: ſince, if it
could
be reduc'd to a certainty, tis proba­
ble
that the diſcovery would not be un­
uſeful
.
And, to illuſtrate this matter a little
more
, we will adde, That we made a ſhift
to
try the Experiment in one of our above
mention
'd ſmall Receivers, not containing
1a Quart; but that (agreeably to what we
formerly
obſerved) we found it as difficult
to
bring this to be quite empty as to eva­
cuate
the greater; the leaſt external Air
that
could get in (and we could not poſſi­
bly
keep it all perfectly out) ſufficing in ſo
ſmall
a Veſſel to diſplay a conſiderable
preſſure
upon the ſurface 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 ſmall Veſſel, upon
the
very firſt 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.
But, on this occaſion, I hold it not un­
fit
to give Your Lordſhip notice that I
hop
'd, from the deſcent of the Quick­
ſilver
in the Tube upon the firſt ſuck, to
derive
this advantage: that I ſhould thence
be
enabled to give a near gueſs at the pro­
portion
of force betwixt the preſſure of
the
Air (according to its various ſtates, as
to
Denſity and Rarefaction) and the gra­
vity
of Quick-ſilver, then hitherto has
been
done.
For in our Experiment there
are
diverſe things given, that may be
made
uſe of towards ſuch a diſcovery.
1For firſt we may know the capacity of the
Receiver
wherein the Experiment is
made
, ſince, by filling it with water, we
may
eaſily compute how many Quarts, or
Meaſures
of any other denomination, it
contains
of Air; which Air, when ſhut
up
in the Veſſel, may be ſuppoſ'd to have
a
preſſure equal to that of the Atmo­
ſphere
; ſince it is able to keep the Quick­
ſilver
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 braſs
Cylinder
empty'd by the drawing down
of
the Sucker (its bore and height being
mention
'd in the deſcription 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 firſt ſuck.
And
we
may alſo eaſily define, either in weight
or
cubick meaſures the Cylinder of
Quick-ſilver
that anſwers 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-ſilver
, the altitude at which it reſts
upon
the firſt exſuction.) But though, if
this
Experiment were very watchfully
try
'd in Veſſels of ſeveral ſizes, and the
1various deſcents of the Quick-ſilver com­
par
'd among themſelves, 'tis not impro­
bable
that ſome ſuch thing as we hop'd for
may
thereby be diſcover'd.
Yet becauſe
not
onely the ſolid contents of as much
of
the Glaſs-tube as remains within the
concave
ſurface of the Receiver, and
(which is more difficult) the varying con­
tents
of the Veſſel containing the Mer­
cury
, and of as much of the Mercury it
ſelf
as is not in the Tube, muſt be dedu­
cted
out of the capacity of the Receiver;
but
there muſt alſo 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 ſo
repleniſh
'd with Air as the Receiver it ſelf
at
firſt was: becauſe there paſſes no more
Air
out of the Receiver into the Cylin­
der
, then is requiſite to reduce the Air in
the
cavity of the Cylinder, and in that of
the
Receiver to the ſame meaſure of dila­
tation
: Becauſe of theſe (I ſay) and ſome
other
difficulties that require more skill in
Mathematicks
then I pretend to, and much
more
leaſure then my preſent occaſions
would
allow me, I was willing to refer the
nicer
conſideration of this matter to ſome
1of our Learned and Acurate Mathema­
ticians
, thinking it enough for me to have
given
the Hint already ſuggeſted.
For further confirmation of what hath
been
delivered, we likewiſe tryed the Ex­
periment
in a Tube of leſs then two foot
long
: and, when there was ſo much Air
drawn
out of the Veſſel, that the remain­
ing
Air was not able to counterballance
the
Mercurial Cylinder, the Quick-ſilver
in
the Tube ſubſided ſo viſibly, that (the
Experiment
being try'd in the little Veſ­
ſel
lately mention'd) at the firſt ſuck it
fell
above a ſpan, 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 almoſt to the top of
the
Tube: So little matters it how heavy
or
light the Cylinder of Quick ſilver to
ſubſide
is, provided its gravity over­
power
the preſſure of as much external
Air
as bears upon the ſurface of that Mer­
cury
into which it is to fall.
Laſtly we alſo obſerv'd, That if (when
the
Mercury in the Tube had been drawn
down
, and by an Ingreſs permitted to the
external
Air, impell'd up again to its for­
mer
height) there were ſome more Air
thruſt
up by the help of the Pump into
1the Receiver, the Quick-ſilver in the Tube
would
aſcend much above the wonted
height
of 27 digits, and immediatly up­
on
the letting out of that Air would fall
gain
to the height it reſted at before.
Your Lordſhip will here perhaps expect,
that
as thoſe who have treated of the Tor­
ricellian
Experiment, have for the moſt
part
maintaind the Affirmative, or the Ne­
gative
of that famous Queſtion, Whether
or
no that Noble Experiment infer a Va­
cuum
? ſo I ſhould on this occaſion inter­
poſe
my Opinion touching that Contro­
verſie
, or at leaſt declare whether or no, in
our
Engine, the exſuction of the Air do
prove
the place deſerted by the Air ſuck'd
out
, to be truly empty, that is, devoid of
all
Corporeal Subſtance.
But beſides that,
I
have neither the leiſure, nor the ability,
to
enter into a ſolemn Debate of ſo nice a
Queſtion
; Your Lordſhip may, if you
think
it worth the trouble, in the Dia­
logues
not long ſince referr'd to, finde the
Difficulties
on both ſides repreſented;
which
then made me yield but a very wa­
vering
aſſent to either of the parties con­
tending
about the Queſtion: Nor dare I
yet
take upon me to determine ſo difficult
a
Controverſie.
1
For on the one ſide it appears, that not­
withſtanding
the exſuction of the Air, our
Receiver
may not be deſtitute of all Bo­
dies
, ſince any thing placed in it, may be
ſeen
there; which would not be, if it
were
not pervious to thoſe Beams of
Light
which rebounding from the ſeen
Object
to our eyes, affect us with the ſenſe
of
it: And that either theſe Beams are
Corporeal
Emanations from ſome lucid
body
, or elſe at leaſt the light they convey
doth
reſult from the brisk Motion of ſome
ſubtle
Matter, I could, if I miſtake not,
ſufficiently
manifeſt out of the Dialogues
above-mention
'd, if I thought your Lord­
ſhip
could ſeriouſly imagine that Light
could
be convey'd without, at leaſt, having
(if I may ſo ſpeak) a Body for its Ve­
hicle
.
By the ſixteenth Experiment, it alſo
appears
that the cloſeneſs of our Receiver
hinders
it not from admitting the Efflu­
via
of the Load-ſtone; which makes it
very
probable that it alſo freely admits
the
Magnetical ſteams of the Earth; con­
cerning
which, we have in another Trea­
tiſe
endeavour'd to manifeſt that numbers
of
them do always permeate our Air.
But on the other ſide it may be ſaid,
1That as for the ſubtle Matter which makes
the
Objects encloſed in our evacuated Re­
ceiver
, viſible, and the Magnetical Efflu­
via
of the Earth that may be preſum'd to
paſs
thorow it, though we ſhould grant
our
Veſſel not to be quite devoyd of
them
, yet we cannot ſo reaſonably affirm
it
to be repleniſh'd with them, as we may
ſuppoſe
, that if they were gather'd toge­
ther
into one place without Intervals be­
tween
them, they would fill but a ſmall
part
of the whole Receiver.
As in the
thirteenth
Experiment, a piece of Match
was
inconſiderable for its bulk, whileſt its
parts
lay cloſe together, that afterwards
(when the Fire had ſcatter'd them into
ſmoke
) ſeem'd to repleniſh all the Veſſel.
For (as elſewhere our Experiments have
demonſtrated
) both Light and the Efflu­
via
of the Load-ſtone, may be readily ad­
mitted
into a Glaſs, Hermetically ſeal'd,
though
before their Admiſſion, as full of
Air
as hollow Bodies here below are wont
to
be, ſo that upon the exſuction of the
Air
, the large ſpace deſerted by it, may
remain
empty, notwithſtanding the pre­
tence
of thoſe ſubtle Corpuſcles, by
which
Lucid and Magnetical Bodies pro­
duce
their effects.
1
And as for the Allegations above
mention
'd, they ſeem to prove but that
the
Receiver devoy'd of Air, May be re­
pleniſh
'd with ſome ſuch Etherial Matter,
as
ſome Modern Naturaliſts write of; but
not
that it really is ſo. And indeed to me
it
yet ſeems, that as to thoſe ſpaces which
the
Vacuiſts would have to be empty, be­
cauſe
they are manifeſtly devoid of Air;
and
all groſſer Bodies, the Pleniſts (if I
may
ſo call them) do not prove that ſuch
ſpaces
are repleniſh'd with ſuch a ſubtle
Matter
as they ſpeak of, by any ſenſible
effects
, or operations of it (of which di­
vers
new Tryals purpoſely made, have not
yet
ſhown me any) but onely conclude
that
there muſt be ſuch a Body, becauſe
there
cannot be a Void.
And the reaſon
why
there cannot be a Void, being by
them
taken, not from any Experiments,
or
Phænomena of Nature, that clearly and
particularly
prove their Hypotheſis, but
from
their notion of a Body, whoſe Na­
ture
, according to them, conſiſting one­
ly
in extenſion (which indeed ſeems the
property
moſt eſſential to, becauſe inſepa­
rable
from a Body) to ſay a ſpace devoid
of
Body, is to ſpeak in the School-mens
Phraſe
, a Contradiction in Adjecto: This
1reaſon, I ſay, being thus deſum'd, ſeems
to
make the Controverſie about a Vacu­
um
, rather a Metaphyſical, then a Phyſio­
logical
Queſtion; which therefore we ſhall
here
no longer debate, finding it very dif­
ficult
either to ſatisfie Naturaliſts with
this
Carteſian Notion of a Body, or to
manifeſt
wherein it is erroneous, and ſub­
ſtitute
a better in its ſtead.
But though we are unwilling to exa­
mine
any further the Inferences wont to
be
made from the Torricellian Experi­
ment
, yet we think it not impertinent to
preſent
Your Lordſhip with a couple of
Advertiſements
concerning it.
Firſt, then if in trying the Experiment
here
or elſewhere, you make uſe of the
Engliſh
meaſures that Mathematicians
and
Tradeſmen are here wont to imploy,
You
will, unleſs you be forewarn'd of it,
be
apt to ſuſpect that thoſe that have writ­
ten
of the Experiment have been miſta­
ken
.
For whereas men are wont gene­
rally
to talk of the Quick-ſilver's remain­
ing
ſuſpended at the heighth of between
ſix
or ſeven and twenty Inches; we com­
monly
obſerv'd, when divers years ſince
we
firſt were ſollicitous about this Expe­
riment
, that the Quick-ſilver in the Tube
1reſted at about 29 Inches & an half above
the
ſurface of the Reſtagnant Quick-ſilver
in
the Veſſel, which did at firſt both amaze
and
perplex us, becauſe though we held it
not
improbable that the difference of the
groſſer
Engliſh Air, and that of Italy and
France, might keep the Quick-ſilver from
falling
quite as low in this colder, as in
thoſe
warmer Climates; yet we could
not
believe that that difference in the Air
ſhould
alone be able to make ſo great a one
in
the heights of the Mercurial Cylinders;
and
accordingly upon enquiry we found,
that
though the various denſity of the
Air
be not to be over-look'd in this Ex­
periment
, yet the main Reaſon why we
found
the Cylinder of Mercury to conſiſt
of
ſo many Inches, was this, That our
Engliſh
Inches are ſomewhat inferior in
length
to the digits made uſe of in Fo­
rein
Parts, by the Writers of the Expe­
riment
.
The next thing I deſire Your Lordſhip to
take
notice of, is, That the heigth of the
Mercurial
Cylinder is not wont to be found
altogether
ſo great as really it might
prove
, by reaſon of the negligence or in­
cogitancy
of moſt that make the Experi­
ment
.
For often times upon the opening
1of the inverted Tube into the Veſſell'd
Mercury
, you may obſerve a bubble of
Air
to aſcend from the bottom of the
Tube
through the ſubſiding Quick-ſilver
to
the top; and almoſt always you may,
if
you look narrowly, take notice of a
multitude
of ſmall bubbles all along the
inſide
of the Tube betwixt the Quick­
ſilver
& the glaſs: (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-ſilvers forſaking
the
upper part of the Tube, do break in­
to
that deſerted ſpace where they finde
little
or no reſiſtance to their expanding
of
themſelves.
Whether this be the rea­
ſon
that upon the Application of warm
Bodies
to the emptyed part of the Tube,
the
ſubjacent Mercury would be depreſſ'd
ſomewhat
lower, we ſhall not determine;
though
it ſeem very probable, eſpecially
ſince
we found that upon the application
of
Linnen cloaths dipped in Water, to
the
ſame part of the Tube, the Quick­
ſilver
would ſomewhat aſcend, as if the
cold
had condenſ'd the Impriſon'd Air,
that
preſſ'd upon it, into a leſſer room.
But that the deſerted ſpace is not wont to
be
totally devoid of Air, we were induc'd
1to think by ſeveral Circumſtances. For
when
an eminent Mathematician, and ex­
cellent
Experimenter, had taken great
pains
and ſpent much time in accuratly fil­
ling
up a Tube of Mercury, we found
that
yet there remain'd ſtore of inconſpi­
cuous
bubbles, by inverting the Tube,
letting
the Quick-ſilver fall to its wonted
heighth
; and by approaching (by de­
grees
) a red hot Iron to the out-ſide of the
Tube
, over againſt the upper part of the
Mercurial
Cylinder, for hereby the little
unheeded
bubbles, being mightily expan­
ded
, aſcended in ſuch numbers, and ſo faſt
to
the deſerted ſpace, that the upper part
of
the Quick-ſilver ſeem'd, to our wonder,
to
boyl.
We further obſerv'd, That in
the
tryals of the Torricellian Experiment
we
have ſeen made by others, and (one
excepted
) all our own, we never found that
upon
the inclining of the Tube the Quick­
ſilver
would fully reach to the very top of
the
ſeal'd end: which argued, that there
was
ſome Air retreated thither that kept
the
Mercury out of the unrepleniſh'd
ſpace
.
If Your Lordſhip ſhould now demand
what
are the beſt expedients to hinder the
intruſion
of the Air in this Experiment;
1we muſt anſwer, That of thoſe which are
eaſily
intelligible without ocular demon­
ſtration
, we can at preſent ſuggeſt upon
our
own tryals no better then theſe.
Firſt,
at
the open end of the Tube the Glaſs
muſt
not onely be made as even at the ed­
ges
as you can, but it is very conveni­
ent
(eſpecially if the Tube be large) that
the
bottom be every way bent inwards,
that
ſo the Orifice, not much exceeding a
quarter
of an Inch in Diameter, may be
the
more eaſily and exactly ſtopp'd by the
Experimenter
's finger; between which
and
the Quick-ſilver, that there may be
no
Air intercepted (as very often it hap­
pens
that there is) it is requiſite that the
Tube
be fill'd as full as poſſibly it can be,
that
the finger which is to ſtop it, preſſing
upon
the accumulated and protuberant
Mercury
, may rather throw down ſome,
then
not finde enough exactly to keep out
the
Air.
It is alſo an uſeful and compen­
dious
way not to fill the Tube at firſt
quite
ful of Mercury, but to leave near the
top
about a qnarter of an Inch empty; for
if
you then ſtop the open end with your
finger
, and invert the Tube that quarter
of
an Inch of Air will aſcend in a great
bubble
to the top, and in its paſſage thi-
1ther, will gather up all the little bubbles,
and
unite them with itſelf into one great
one
, ſo that if by reinverting the Tube
you
let that bubble return to the open
end
of it, you will have a much cloſer Mer­
curial
Cylinder then before, and need but
to
adde a very little Quick-ſilver more to
fill
up the Tube exactly.
And laſtly, as for
thoſe
leſſer and inconſpicuous parcels of
Air
which cannot this way be gleaned up,
You
may endeavor before you invert the
Tube
, to free the Quick-ſilver from them
by
ſhaking the Tube, and gently knock­
ing
on the out-ſide of it, after every little
parcel
of Quick-ſilver which you pour in;
and
afterwards, by forcing the ſmall la­
titant
bubbles of Air to diſcloſe them­
ſelves
and break, by imploying a hot Iron
in
ſuch 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 ſhort Tube:
which
we therefore mention, becauſe we
have
found, by experience, that in ſhort
Tubes
a little Air is more prejudicial to
the
Experiment then in long ones, where
the
Air having more room to expand it
1ſelf, does leſs potently preſs upon the ſub­
jacent
Mercury.
And ſince we are fallen upon the conſi­
deration
of the Altitude of the Mercurial
Cylinder
, I muſt not conceal from Your
Lordſhip
an Experiment relating thereun­
to
, which perhaps will ſet both You and
many
of your Friends the Virtuoſi a think­
ing
; and, by diſcloſing ſome things
bout
the Air or Atmoſphere that have
ſcarce
hitherto been taken notice of, may
afford
you ſome hints conducive to a fur­
ther
diſcovery of the ſubject of this
piſtle
.
WE took a Glaſs Tube, which,

though
it were not much above
three
Foot long, we made choice of be­
cauſe
it was of a more then ordinarily
even
thickneſs.
This we fill'd with Mer­
cury
, though not with as much care as we
could
, yet with ſomewhat more then is
wont
to be uſed in making the Torricellian
Experiment
.
Then, having according to
the
manner inverted the Tube, and open'd
the
mouth of it beneath the ſurface of
ſome
other Quick-ſilver, that in the Tube
fell
down to the wonted heigth, leaving,
1as is uſual, ſome little Particles of Air in
the
ſpace it deſerted, as we gheſt by ob­
ſerving
, that upon the Application of hot
Bodies
to the upper part of the Tube, the
Quick-ſilver
would be a little depreſſ'd.
Laſtly, having put both the Tube and the
Veſſel
it lean'd on into a convenient
Wooden
Frame, to keep them from miſ­
chances
: we plac'd that Frame in a Win­
dow
within my Bed-chamber, that I might
both
keep the Mercury from being ſtirr'd,
and
have opportunity to watch from time
to
time the Phænomena it was to exhibit.
For the better diſcovery of which, when
the
Quick-ſilver both in the Tube and
ſubjacent
Veſſel was perfectly at reſt, we
took
notice, by a mark made on the out­
ſide
of the Glaſs, how high the included
Liquor
then reach'd.
Experi­
ment
18.
During ſeveral Weeks that the Tube
was
kept in that Window (which was very
rarely
open'd) I had the opportunity to
obſerve
, that the Quick-ſilver did ſome­
times
faintly imitate the Liquor of a
Weather-glaſs
, ſubſiding a little in warm,
and
riſing a little in cold Weather, which
we
aſcribed to the greater or leſſer preſſure
of
that little Air that remain'd at the top
of
the Tube, expanded or condenſ'd by
1the heat or cold that affected the ambient
Air
.
But that which I was chiefly careful
to
obſerve, was this, That oftentimes the
Quick-ſilver
did riſe and fall in the Tube,
and
that very notably, without conforming
it
ſelf to what is uſual in Weather-glaſſes,
whoſe
Air is at the top, nay quite contrary
thereunto
: for ſometimes I obſerv'd it in
very
cold weather (ſuch as this Winter has
already
afforded us good ſtore of) to fall
down
much lower then at other times,
when
by reaſon of the abſence of both
Froſt
, Snow, and ſharp Winds, the Air was
comparatively
much warmer.
And I fur­
ther
obſerv'd, That ſometimes the Quick­
ſilver
would for ſome days together reſt
almoſt
at the ſame height; and at other
times
again it would in the compaſs of the
ſame
day conſiderably 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 conſtantly
kept
a good Fire) nor in any thing elſe, to
which
either I, or ſome eminently Learned
Men
whom I then acquainted with the
Experiment
, could reaſonably impute
ſuch
a change: Eſpecially conſidering that
the
ſpace wherein the Mercury wandred up
and
down, within about five Weeks,
mounted
to full two Inches, of which we
1found by our ſeveral marks whereby we
had
taken notice of its ſeveral removes, that
it
had deſcended about (9/16) of an Inch from the
place
where it firſt ſetled, & the other Inch
and
(7/16) it had aſcended.
And it ſeems 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 Impriſon'd Air, by having
more
room to diſplay themſelves in,
might
not have had ſo ſtrong a Spring to
work
upon the Quick-ſilver 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,
becauſe
we would gladly have try'd an in­
genious
Experiment which was ſuggeſted
unto
us by that excellent Mathematician
Mr
. Wren, who being invited to name any
thing
he would have us try touching the
preſſure
of the Air, deſired us to obſerve
whether
or no the Quick-ſilver in a long
Tube
would not a little vary its height ac­
cording
to the Tides, eſpecially about the
New
and Full Moon, about which times
Mariners
obſerve thoſe great Flowings
and
Ebbs of the Sea, that they call the
1Spring-Tides. For he ſagaciouſly and
plauſibly
conjectur'd that ſuch obſervati­
ons
accurately made, would diſcover the
truth
or erroneouſneſs of the Carteſian
Hypotheſis
concerning the Ebbing and
Flowing
of the Sea: which Des Cartes
aſcribes
to the greater preſſure made upon
the
Air by the Moon, and the Intercur­
rent
Ethereal Subſtance at certain times
(of the Day, and of the Lunary Moneth)
then
at others.
But in regard we found
the
Quick-ſilver in the Tube to move up
and
down ſo uncertainly, by reaſon, as it
ſeems
, of accidental mutation in the Air;
I
ſomewhat doubt whether we ſhall finde
the
Altitude of the Quick-ſilver to vary
as
regularly as the Experiment is ingeni­
ouſly
propoſ'd.
The ſucceſs we ſhall (God
permitting
us to make tryal of it) acquaint
Your
Lordſhip with; and in the mean
time
take notice, that when we had occa­
ſion
to take the Tube out of the Frame
(after it had ſtaid there part of November
and
part of December) a good Fire being
then
in the room, becauſe it was a Snowy
day
, we found the Quick-ſilver in the
Tube
to be above the upper ſurface of
the
ſubjacent Mercury 29 Inches three
quarters
.
1
If Your Lordſhip ſhould now ask me
what
are the true cauſes of this varying al­
titude
of the Mercurial Cylinder; I ſhould
not
undertake to anſwer ſo difficult a que­
ſtion
, and ſhould venter to ſay no more,
then
that among divers poſſible cauſes to
which
it may be aſcribed, it would not be,
perhaps
, abſurd to reckon theſe that fol­
low
.
Firſt then we may conſider, 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-ſilver will
readily
aſcend almoſt to the very top of
it
, and ſo take up eight or nine tenth parts,
and
perhaps more of that ſpace which it
deſerted
before: which would not happen
if
that whole ſpace had been full of unra­
rified
Air, ſince that (as tryal may eaſily
ſatisfie
you) would not have ſuffer'd it
ſelf
to be thruſt into ſo narrow a room by
ſo
weak a preſſure.
So that although in
our
Tube when the included Air was
heated
, the Quick-ſilver was ſomewhat
depreſſ
'd: Yet there is this difference be­
twixt
ſuch a Tube and common Weather­
Glaſſes
, that in theſe the included and the
1ambient Air are in an Æquilibrium as to
preſſure
, and the weight of the Water
that
keeps them ſeparate is ſcarce conſi­
derable
.
Whereas in ſuch a Tube as we
are
ſpeaking of, the Air within is very
much
more dilated then that without; and
'tis not ſo much the ſpring or reſiſtance
of
the included Air, as the weight of the
Mercurial
Cylinder it ſelf that hinders the
Quick-ſilver
from aſcending higher; for
if
we ſhould ſuppoſe that deſerted part of
the
Tube perfectly devoid of Air, yet
would
the Quick-ſilver riſe but a little
higher
in it, and be far from filling it, in
regard
the outward Air would not be
able
to impel up ſuch a weight much
higher
: whereas it may, by our former
Experiments
appear, that if all the Air in
the
upper part of a Weather-Glaſs were
away
, the Water would be impell'd up to
the
very top of it, though the Pipe were
above
thirty Foot long.
We may next conſider, that this ra­
rified
Air at the upper part of our Tube
being
exactly ſhut up betwixt the Glaſs
and
the Quick-ſilver, it was ſcarce ſubject
to
any diſcernable alterations, ſave thoſe
it
receiv'd from heat and cold.
1
And we may further conſider that yet
the
external Air or Atmoſphere is ſubject
to
many alterations, beſides them that
proceed
from either of thoſe Quali­
ties
.
For the Experiment that occaſion'd
this
Diſcourſe, ſeems to make it proba­
ble
enough that there may be ſtrange
Ebbings
and Flowings, as it were, in the
Atmoſphere
; or at leaſt, that it may ad­
mit
great and ſudden Mutations, either as
to
its Altitude or its Denſity, from cauſes,
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 Lordſhip
in
minde of the Pains and Aches that are
often
complain'd of by thoſe that have
had
great Wounds or Bruiſes, and that
doe
preſage great Mutations in the Air
oftentimes
, whilſt to ſtrong and healthy
Perſons
no ſign of any ſuch thing appears.
And that is alſo very memorable to this
purpoſe
, which I remember I have ſome­
where
read in a Book of the Ingenious
Kircherus, who giving a pertinent admoni­
tion
concerning the various refractions
that
may happen in the Air, relates, That
1during his ſtay in Malta, he often ſaw
Mount
Ætna, though the next day, not­
withſtanding
its being extreamly clear, he
could
not ſee it; adding, that Vintemillius,
a
very Learned Perſon, did oftentimes,
from
a Hill he names, behold the whole
Iſland
he calls Luprica protuberant above
the
Sea, though at other times, notwith­
ſtanding
a clear Sky, he could not ſee it.
And though perhaps this may be in part
ſcribed
to the various light & poſition of
the
ſun, or to the various diſpoſition of the
Spectators
eye, or peradventure to ſome
other
cauſe; yet the moſt probable cauſe
ſeems
to be the differing Denſity of the
Air
, occaſion'd by Exhalations capable to
increaſe
the refraction, and conſequently
bring
Beams to the Eye, which otherwiſe
would
not fall on it.
We have likewiſe
in
another Treatiſe mention'd our having
often
obſerv'd with Teleſcopes a plenty
of
Steams in the Air, which without ſuch
a
help would not be taken notice of, and
which
as they were not at all times to be
ſeen
even through a Teleſcope, ſo they
did
ſometimes, eſpecially after a ſhower of
Rain
, haſtily diſappear: and when we
have
viſited thoſe places that abound with
Mines
, we have ſeveral times been told
1by the Diggers, that even when the Sky
ſeem
'd clear, there would not ſeldom ſud­
denly
ariſe, and ſometimes long continue,
a
certain Steam (which they uſually call a
damp
) ſo groſs and thick, that it would
oftentimes
put out their very Candles, if
they
did not ſeaſonably prevent it.
And
I
think it will eaſily be granted, that the
aſcenſion
of ſuch Steams into this or that
part
of the Air, and their mixing with it,
are
very like to thicken it; as on the
ther
ſide either heat or the ſudden conden­
ſation
of the Air in another part of the At­
moſphere
(to mention now no other cau­
ſes
) are capable of rarifying it.
Nor will it very much import the main
ſcope
of our Diſcourſe, whether it be
ſuppoſ
'd that the copious Steams the
earth
ſends into the air, thicken that part
of
the Atmoſphere that receives them,
and
make it more heavy: Or that ſome­
times
the Fumes may aſcend with ſuch ce­
lerity
, that though the Air be thicken'd
yet
they rather diminiſh then encreaſe its
gravitation
, in regard that the quickneſs
of
their aſcent, not onely keeps them
from
gravitating themſelves, but may
hinder
the preſſing downwards of many
Aërial
Corpuſcles that they meet with in
1their way upwards. This, I ſay, is of
no
great importance to our preſent Diſ­
courſe
, ſince either way the Terreſtrial
Steam
may here and there conſiderably
alter
the gravity or preſſure of the At­
moſphere
.
Your Lordſhip may alſo be pleaſed to
remember
, That by our ſeventeenth Ex­
periment
it appear'd that as when the Air
in
the Receiver was expanded more then
ordinarily
, the Quick-ſilver in the Tube
did
proportionably ſubſide; ſo when the
Air
in the ſame Receiver was a little more
then
ordinarily compreſſ'd, it did impell
up
the Quick-ſilver in the Tube above
the
wonted height of betwixt ſix and ſe­
ven
and twenty digits.
And if to theſe things we annex, that
for
ought we can finde by tryals purpoſe­
ly
made, the degree of rarity or denſity
of
the Air, ſhut up into our Receiver, does
not
ſenſibly alter its temperature as to
cold
or heat.
It will not, I hope, appear
abſurd
to conceive, That ſince the Air,
included
in the Tube, could but very faint­
ly
hinder the aſcent of the Quick-ſilver,
or
preſs it downwards, ſince too that inclu­
ded
Air could ſcarce immediately receive
any
ſenſible alteration, ſave either by heat
1or cold. And ſince alſo that according to
the
bare denſity or rarity of the Air in­
cumbent
on the ſubjacent Quick-ſilver in
the
Veſſel, that in the Tube was impell'd
more
or leſs high; ſuch changes happen­
ing
in the neighboring part of the out­
ward
Air, either by the aſcenſion of groſs
or
copious exhalations, or by any other
cauſe
(of which there may be divers) as
were
capable to make conſiderable altera­
tions
in the conſiſtence of the Air, as to
rarity
and denſity, may be able propor­
tionably
to alter the heighth of the
Quick-ſilver
: I rather ſay, that ſuch alte­
rations
may be, then that they are the
cauſes
of our Phænomenon, becauſe I think
it
ſufficient, if I have propoſ'd conje­
ctures
not altogether irrational about a
new
Myſtery of Nature, touching which,
the
chief thing I pretend to, is to give oc­
caſion
to the Curious to inquire further
into
it then I have been yet able to do.
THe ſame Reaſon that mov'd us to

conclude
, that by the drawing of the
Air
out of the Receiver, the Mercury
would
deſcend in a Tube ſhorter then ſix
and
twenty digits, induc'd us alſo to ex-
1pect, that by the ſame means Water
might
be brought to ſubſide in Glaſs
Tubes
of a moderate length, though by
the
noble Experiment, ſaid to have been
accurately
made in France by Monſieur
Paſchal
, we are informed that a Tube of
no
leſs then about two and thirty Foot,
was
found requiſite to make the Experi­
ment
De Vacuo ſucceed with Water in­
ſtead
of Quick-ſilver: ſo tall a Cylinder
of
that lighter Liquor, being, it ſeems,
requiſite
to equal the weight of a Mercu­
rial
Cylinder of ſix or ſeven and twenty
digits
, and ſurmount the preſſure of the
Atmoſphere
.
Experi­
ment
19.
We took then a Tube of Glaſs, Her­
metically
ſeal'd at one end, of about four
foot
in length, and not very ſlender: This
at
the open end we fill'd with common
Water
, and then ſtopt that end till we
had
inverted the Tube, and open'd it be­
neath
the ſurface of a quantity of the like
Water
, contain'd in a ſomewhat deep and
ſlender
Veſſel.
This Veſſel, with the
Tube
in it, was let down into the Recei­
ver
, and the Receiver being cloſ'd up af­
ter
the accuſtom'd manner, the Pump was
ſet
awork.
1
As much of the event as concerns our
preſent
purpoſe, was this, That till a con­
ſiderable
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
requiſite that a great part of the Air
formerly
contain'd in the Receiver, ſhould
be
drawn out, to bring the remaining
Air
to an Æquilibrium with ſo ſhort and
light
a Cylinder of Water.
But when
once
the Water began to fall in the Tube,
then
each exſuction of Air made it de­
ſcend
a little lower, though nothing near
ſo
much as the Quick-ſilver at the begin­
ning
did in the Experiment formerly men­
tion
'd.
Nor did there appear ſo much
inequality
in the ſpaces tranſmitted by
the
Water in its deſcent, as there did in
thoſe
obſerv'd in the fall of the Quick­
ſilver
, of which the cauſe will ſcarce ſeem
abſtruſe
to him that ſhall duly reflect up­
on
what has been already deliver'd.
And
whereas
we drew down the Quick-ſilver
in
the Tube ſo far as to bring it within an
Inch
of the ſurface of the other Quick­
ſilver
into which it was to fall; the loweſt
we
were able to draw down the Water
was
, by our conjecture, to about a Foot
1or more above the ſurface of that in the
Veſſel
; of which I know not whether it
will
be needful to aſſign ſo obvious a cauſe
as
that, though the little Air remaining
in
the Receiver could not hinder a Cylin­
der
of above an Inch high of Quick-ſilver
from
ſubſiding; yet it might very well
be
able, by its preſſure, to countervail the
weight
of a Cylinder of a Foot long or
more
, of a Liquor ſo much leſs ponderous
then
Quick-ſilver, 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
gain
to the higher parts of the Tube.
We will adde no more concerning this
Experiment
, ſave that having try'd it in
one
of our ſmall Receivers, we obſerv'd,
That
upon the firſt exſuction of the Air
the
Water did uſually ſubſide divers In­
ches
, and at the ſecond (exſuction) fall
down
much lower, ſubſiding ſometimes
near
two Foot; as alſo that upon the let­
ting
in of the Air from without, the Wa­
ter
was impell'd up with very great ce­
lerity
.
1
THat the Air has a notable Elaſtical

power
(whenceſoever that proceeds)
we
have, I ſuppoſe, abundantly evinc'd,
and
it begins to be acknowledg'd by the
eminenteſt
Modern Naturaliſts.
But whe­
ther
or no there be in Water ſo much as
a
languid one, ſeems hitherto to have been
ſcarce
conſider'd, nor has been yet, for
ought
I know, determin'd either way by
any
Writer, which invited us to make the
following
Experiment.
Experi­
ment
20.
There was taken a great Glaſs-bubble,
with
a long neck; (ſuch as Chymiſts are
wont
to call a Philoſophical Egg) which
being
fill'd with common Water till the
Liquor
reach'd about a ſpan above the
bubble
, and a piece of Paper being there
paſted
on, was put unſtop'd into the Re­
ceiver
, and then the Air was ſuck'd out
after
the wonted manner.
The event was
this
, That a conſiderable part of the Air,
pent
up in the Receiver, was drawn out
before
we diſcern'd any expanſion of the
Water
; but, continuing the labor of
pumping
, the Water manifeſtly began to
aſcend
in the ſtem of the Glaſs, and di­
vers
bubbles looſening themſelves from
1the lower parts of the Veſſel, 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 ſwell, 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 Glaſs did ſuddenly riſe
bout
the breadth of a Barly-corn in the
Neck
of the Glaſs, and ſo attain'd, by
degrees
, to a conſiderable height above
the
mark formerly mention'd.
And at
length
(to make the expanſion of the Wa­
ter
more evident) the outward Air was
ſuddenly
let in, and the Water immedi­
ately
ſubſided and deſerted all the ſpace it
had
newly gain'd in the Glaſs.
And, on this occaſion, it will not per­
haps
be amiſs to acquaint Your Lordſhip
here
(though we have already mention'd
it
in another Paper, to another purpoſe)
with
another Expedient that we made uſe
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 Philoſophy
Dr
. Wilkins, doing me the Honor to
come
himſelf, and bring ſome of his in­
quiſitive
Friends to my Lodging, we
1there had in readineſs a round and hollow
Veſſel
of Pewter, great enough to con­
tain
two pounds of Water, and exactly
cloſe
every where, but at one little hole
where
it was to be fill'd; then partly by
ſucking
out the Air, and partly by inject­
ing
Water with a Syringe, it was (not
without
ſome difficulty) fill'd up to the
top
; and that hole being plac'd directly
upwards
, there was a little more Water
leiſurely
forc'd in by the Syringe.
Upon
which
, though the Veſſel were permitted
to
reſt, and the hole kept in its former po­
ſture
, yet the compreſſ'd Water leiſurely
ſwell
'd above the Orifice of the hole, and
divers
drops ran over along the ſides of the
Veſſel
.
After this, we cauſ'd a skilful Pew­
terer
(who had made the Globe) to cloſe
it
up in our preſence with Soder ſo exqui­
ſitely
, that none ſuſpected there was any
thing
left in it beſides Water.
And laſt­
ly
, the Veſſel thus ſoder'd up, was wari­
ly
and often ſtruck in divers places with a
Wooden
Mallet, and thereby was mani­
feſtly
compreſſ d, whereby the incloſed
Water
was crouded into leſs room then it
had
before: And thereupon when we took
a
Needle, and with it and the Mallet per­
forated
the Veſſel, and drew out the
1Needle again; the Water (but in a very
ſlender
Stream) was ſuddenly thrown af­
ter
it into the Air, to the height of two
or
three Feet.
As for the other Phænome­
na
of this Experiment, ſince they belong
not
to our preſent purpoſe, and are partly
mention
'd in another of our Papers, we
ſhall
, inſtead of recording them here, give
this
Advertiſement: That as evidently
as
this Experiment, and that made in our
Receiver
, ſeem to prove a power in the
Water
to expand and reſtore it ſelf after
compreſſion
; yet for a reaſon to be met
with
ere long, I judged it not ſafe to in­
fer
that Concluſion from theſe Premiſes,
till
I had made ſome of the following try­
als
, to the mention of which I will there­
fore
haſten.
TO diſcover whether the Expanſion

of
the Water really proceeded
from
an Elaſtical power in the parts of
the
Water it ſelf, we thought it requiſite
to
try two things: The one, Whether or no
the
Atmoſphere gravitates upon Bodies
under
Water; and the other, Whether
in
caſe it do gravitate, the Intumeſcence
of
the Water may not be aſcribed to ſome
1ſubſtance ſubtler then it ſelf, reſiding
it
.
In order to the ſatisfying my ſelf about
the
firſt of theſe, I intended to let down
into
the Receiver a Veſſel of Water,
wherein
ſhould be immerſ'd a very ſmall
oyl
'd Bladder, almoſt devoid of Air, but
ſtrongly
ty'd up at the Neck with a ſtring,
and
detain'd a little under Water by ſuch
a
weight faſten'd to that ſtring, as ſhould
juſt
be able to keep the Bladder from
ſwimming
, and no more.
For I ſuppoſ'd,
that
if when all things were thus order'd,
the
Receiver were empty'd, in caſe there
were
any ſuch preſſure of the Atmoſphere
upon
Water, as I was inclin'd to believe,
the
Air within the Bladder, being upon the
exſuction
of the Air within the Receiver,
freed
from that preſſure, and being preſſ'd
onely
by the ſmall weight of the in­
cumbent
Water, would conſiderably ex­
pand
it ſelf; but whil'ſt we were prepa­
ring
Bladders for this Experiment, there
occurr
'd an eaſie way for the making at
once
both the Diſcoveries I deſir'd.
Experi­
ment
21.
We took then a Glaſs Viol, containing
by
gheſs a pound and ſome ounces of
Water
, this we fill'd top full, and then
we
put into the Neck of it a Glaſs Pipe
a
pretty deal bigger then a Gooſe Quill,
1open at both ends, and of divers Inches
in
length: One end of this Pipe was ſo
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
, otherwiſe 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 paſted over againſt
the
upper ſurface of the Liquor; the Viol
thus
fitted with the Pipe, was, by ſtrings
let
down into the Receiver, and according
to
the wonted manner exquiſitely cloſ'd
up
in it.
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 riſe higher in the Pipe, at the
ſides
of which ſome little bubbles diſco­
ver
'd themſelves.
After a little while
longer
, the Water ſtill ſwelling, there
appear
'd at the bottom of the Pipe a bub­
ble
about the bigneſs of a ſmall Pea,
which
aſcending through the Pipe to the
top
of the Water, ſtaid there awhile and
then
broke; but the Pump being nimbly
ply
'd, the expanſion of the Water ſo en­
creaſ
'd, that quickly, getting up to the
1top of the Pipe ſome drops of it be­
gan
to run down along the out-ſide of it,
which
oblig'd us to forbear pumping
while
, and give the Water leave to ſub­
ſide
within leſs then two Inches of the
bottom
of the Pipe.
After this the
Pump
being again ſet at work, the bub­
bles
began to aſcend from the bottom
of
the Pipe, being not all of a ſize, but yet
ſo
big, that eſtimating one with another,
they
appear'd to be of the ſize of the ſmal­
ler
ſort of Peas; and of theſe we reckon'd
about
ſixty which came up one after ano­
ther
, beſides ſtore of ſmaller ones, of which
we
made no reckoning: And at length,
growing
weary of reckoning and pumping
too
(becauſe we found, that in ſpight
of
all our pains and induſtry, ſome un­
diſcern
'd Leak or other in the Recei­
ver
hinder'd us from being able to empty
it
altogether) we thought fit to deſiſt for
that
time.
After tryal made of what
peration
the external Air, being let in
upon
the expanded Water, would have;
and
accordingly turning the Key to let in
the
Air, we ſaw, as we expected, that
the
Water in the Pipe in a moment fell
down
almoſt to the bottom of it.
1
Now of this Experiment there are two
or
three Circumſtances yet to be men­
tion
'd, which are no leſs then thoſe alrea­
dy
recited, pertinent to our preſent pur­
poſe
.
In the firſt place then, when the great­
er
part of the Air had been pump'd out of
the
Receiver, the riſing bubbles aſcend­
ed
ſo very ſlowly in the Pipe, that their
Progreſs
was ſcarce diſcernable; which
ſeem
'd to proceed from this, That their
bigneſs
was ſuch, That they could not
ſufficiently
extend themſelves in the
cavity
of the Glaſs, without preſſing
on
both hands againſt the ſides of it,
whereby
they became of more difficult
extruſion
to the Water.
And though it
may
ſeem ſtrange theſe bubbles ſhould
be
of any conſiderable bulk, ſince 'tis
like
they conſiſted of leſſer parcels of
the
Air lurking in the Water, then thoſe
that
were vigorous enough to make their
way
through long before them: yet they
were
commonly much larger then before,
ſome
of them being equal in quantity to
four
or five Peas: Whether this their in­
creaſe
of bulk proceeded from the greater
decrement
of the preſſure of the Air,
1or from the Union of two or three of
thoſe
numerous bubbles which were then
generated
below the bottom of the Pipe,
where
we could not ſee what was done
mong
them.
Another thing we noted in our bubbles
was
, That whereas in ordinary ones the
Air
, together with the thin film of Water
that
inveſts and detains, is wont to ſwell
above
the ſurface of the Water it ſwims
on
, and commonly to conſtitute Hemiſ­
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 ſuch whoſe up­
per
ſurface was either level with or be­
neath
that of the Water, ſo that the up­
per
ſurface being uſually ſomewhat con­
vex
, the leſs protuberant parts of it had
a
pretty quantity of Water remaining
bove
them.
We alſo further obſerv'd, That where­
as
in the bubbles that firſt appear'd in
the
Pipe, the aſcending Air did, as in
ther
common bubbles, make its way up­
wards
, by dividing the Water through
which
it paſſ'd, in thoſe bubbles that ap­
pear
'd at the latter end of our Experi­
ment
, when the preſſure of the little ex-
1ternal Air, remaining in the Receiver,
was
grown inconſiderable, the aſcending
parcels
of Air having now little more
then
the weight of the incumbent Water
to
ſurmount, were able both ſo to expand
themſelves
as to fill up that part of the
Pipe
which they pervaded, & by preſſing
every
way againſt the ſides of it, to lift
upwards
with them what Water they
found
above them, without letting any
conſiderable
quantity glide down along
the
ſides of the Glaſs: So that ſometimes
we
could ſee a bubble thruſt 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,
theſe
tumid bubbles ſuddenly relapſ'd to
their
former inconſpicuouſneſs.
All theſe things laid together ſeem'd
ſufficiently
to confirm that, which the
conſideration
of the thing it ſelf would
eaſily
enough perſwade, namely, That
the
Air, and ſuch like Bodies being under
Water
, may be preſſ'd upon as well by
the
Atmoſphere, as by the weight of the
incumbent
Water it ſelf.
Hence likewiſe we may verifie what we
obſerv
'd at the cloſe of the foregoing
1Experiment, namely, That from the ſole
ſwelling
of Water there recorded, it can­
not
be ſo ſafely concluded that Water,
when
freed from compreſſion, is endowd
with
an Elaſtical power of expanding it
ſelf
, ſince thereby it appears that the In­
tumeſcence
produc'd by that Experiment,
may
(at leaſt in great part) be aſcrib'd to
the
numerous little bubbles which are
wont
to be produc'd in Water, from
which
the preſſure of the Atmoſphere is
in
great meaſure taken off.
So apt are we
to
be miſ-led, even by Experiments them­
ſelves
, into Miſtakes, when either we con­
ſider
not that moſt Effects may proceed
from
various Cauſes, or minde onely thoſe
Circumſtances
of our Experiment, which
ſeem
to comply with our preconceiv'd
Hypotheſis or Conjectures.
And hence it ſeems alſo probable, that
in
the Pores or inviſible little receſſes of
Water
it ſelf there lie commonly inter­
ſperſ
'd many parcels of either Air, or at
leaſt
ſomething Analogous thereunto, al­
though
ſo very ſmall that they have not
been
hitherto ſo much as ſuſpected to
lurk
there.
But if it be demanded how it
appears
that there is interſperſ'd through
the
Body of Water any ſubſtance thinner
1then it ſelf, and why that which produc'd
the
bubbles above mention'd ſhould not
be
reſolutely ſaid to be nothing elſe then
a
more active and ſpirituous part of the
Water
, we ſhall, in order to the Elucida­
tion
of this matter, ſubjoyn to what
was
formerly deliver'd the following Ex­
periment
.
WE recited in our nineteenth Ex­
periment
, how by drawing moſt

of
the Air out of the Receiver, we made
the
Water ſubſide by degrees in a Glaſs
not
four Foot long: We ſhall now adde,
that
in the like Experiment made in ſuch
a
Tube, or a greater, it may be obſerv'd,
That
when the Water begins to fall, there
will
appear ſtore of bubbles faſten'd all
long
to the ſides of the Glaſs; of which
bubbles
, by the agitation of the Veſſel
conſequent
upon pumping, there will ariſe
good
numbers to the top of the Water,
and
there break; and as the Cylinder of
Water
is brought to be lower and lower,
ſo
the bubbles will appear more numerous
in
that part of the Tube which the Water
yet
fills; and the nearer the ſurface of the
Water
, in its deſcent, approaches to theſe
1bubbles, the greater they will grow, be­
cauſe
having the leſs weight and preſſure
upon
them, the Expanſion of that Air
which
makes them, can be the leſs reſiſted
by
the preſſure of the incumbent Water
and
Air; as ſeems probable from hence,
that
upon the letting in a little external
Air
, thoſe bubbles immediately ſhrink.
Experi­
ment
22.
It may indeed, as we lately intimated,
be
conjectur'd, that theſe bubbles pro­
ceed
not ſo much from any Air pre-exi­
ſtent
in the Water, and lurking in the
Pores
of it, as from the more ſubtle parts
of
the Water it ſelf; which by the expan­
ſion
allow'd them upon the diminiſh'd
preſſure
of the ambient Bodies may gene­
rate
ſuch bubbles.
And indeed, I am not
yet
ſo well ſatisfied that bubbles may not
(at leaſt ſometimes) have ſuch an Origina­
tion
: but that which makes me ſuſpect
that
thoſe 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
ſtopt
in its aſcent near an Inch beneath
the
top.
And ſince, if the upper part of
the
Tube had been devoyd of any other
1then ſuch Ethereal matter as was ſubtle
enough
freely to penetrate the pores of
the
Glaſs, the external Air would have
been
able to impel the Water to the top
of
a Tube ſeven or eight times as long as
ours
was; The Phænomenon under conſi­
deration
ſeem'd manifeſtly 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 Glaſs from re­
ceding
, was able to withſtand the preſſure
of
the outward Air.
As we ſee that if
never
ſo little Air remain in the Tube up­
on
the making the Experiment De Vacuo
with
Quick-ſilver, no inclining of the
Tube
, though a long one, will enable a
Man
to impel the Mercury up to the very
top
, by reaſon (as we formerly noted)
of
the reſiſtance of the included Air, which
will
not be compreſſ'd beyond a certain
degree
.
But in order to a further Diſcovery what
our
bubbles were, we will, on this occa­
ſion
, inform Your Lordſhip that we try'd
the
XIXth Experiment in one of our ſmall
Receivers
, and ſound, that upon the draw­
ing
down of the Water, ſo many bubbles
diſcloſ
'd themſelves and broke into the
1upper 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 poſſeſſ'd that
ſpace
at the top of the Tube which was
not
fill'd with Water, we took this courſe
to
examine.
We drew the ſecond time
the
Air out of the Receiver, and found,
that
by reaſon of the body that poſſeſſ'd
the
top of the Tube, we were able not
onely
to make the Water in the Tube fall
to
a level with the ſurface of the Water
in
the Veſſel: But alſo (by plying the
Pump
a little longer) a great way beneath
it
: which ſince it could not well be aſcrib'd
to
the bare ſubſiding of the Water by rea­
ſon
of its own weight, argued that the Wa­
ter
was depreſſ'd by the Air: which was
confirm
'd by the Figure of the ſurface of
the
Water in the Tube, which was much
more
concave then that of Water in
Tubes
of that bigneſs uſes to be.
And
this
further tryal (to adde that upon
the
by) we made at the ſame time, That
when
the Water in the Pipe was drawn
down
almoſt as low as the Water without
it
, we obſerv'd, that (though we deſiſted
1from pumping) by the bare application
of
a hand moderately warm to the deſert­
ed
part of the Tube, the remaining Wa­
ter
would be ſpeedily and notably de­
preſſ
'd.
And having for a while held a
kindled
Coal to the outſide of the Tube,
(the Pump being ſtill unimploy'd, becauſe
the
Veſſel chanced to hold extraordinarily
well
) the Air was by the heat ſo far ex­
panded
, that it quickly drave the Water
to
the bottom of the Tube, which was
divers
Inches beneath the ſurface of the
ambient
Water.
Whereby it appears (by
the
ſame way by which we formerly mea­
ſur
'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.
I conſider'd alſo that in caſe the Bub­
bles
we have been ſpeaking 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 preſſure would not diſ­
cloſe
bubbles as before; and accordingly,
the
Air being again pump'd out, the Wa­
ter
in the Tube deſcended as formerly:
1but for a great while we ſcarce ſaw one
bubble
appear, onely when the Receiver
had
been very much exhauſted, and the
Water
was fallen very low, there appear'd
near
the bottom of the Tube, certain
little
bubbles, which ſeem'd to conſiſt of
ſuch
parcels of Air as had not, by reaſon
of
their ſmalneſs, got up to the top of
the
Water, with the more bulkie and vi­
gorous
ones.
And that which is not in­
conſiderable
, is, That having, by letting
in
the Air, forc'd up the Water into the
Tube
, we could not perceive that it aſ­
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 ſwell
up
and fill the Tube.
And on this occa­
ſion
I remember, that having try'd ſuch an
Experiment
as this with Quick-ſilver in­
ſtead
of Water, in a Tube of about a Foot
and
a half long, wherein it might ſeem
more
hopeful to eſcape bubbles; yet up­
on
the drawing down the Quick-ſilver as
low
as we could, and letting in the exter­
nal
Air upon it, we found that ſome lurk­
ing
particles of Air were got up to the top
of
the Tube, and hinder'd the Quick­
ſilver
from being forc'd up again ſo high.
1And though the Quick-ſilver were by
this
means brought to appear a very cloſe
and
lovely Metalline Cylinder, not inter­
rupted
by interſperſ'd bubbles as before;
yet
having cauſ'd the Air to be again
drawn
out of the Receiver, I could per­
ceive
ſeveral little bubbles to diſcloſe
themſelves
, faſten'd to the inſide of the
Tube
, near the bottom of it; and having
purpoſely
watch'd one or two of the chief­
eſt
, I had the pleaſure to obſerve, that
though
they grew bigger and bigger as
the
ſurface of the Mercurial Cylinder fell
nearer
and nearer to them, ſo as that at
length
they ſwell'd into a conſpicuous
bulk
; yet upon the wary letting in the
Air
upon them, they did not break, but
preſently
ſhrunk up into a littleneſs that
render
'd them inconſpicuous.
Whence it ſeems very probable, if not
certain
, that even in the cloſeſt and moſt
ponderous
Liquors, and therefore much
more
in Water, there may lurk undiſcern­
able
parcels of Air, capable, upon the
removal
of the preſſure of the ambient
Air
(though but in part) and that of the
Liquor
wherein it lurks, to produce con­
ſpicuous
bubbles.
And conſequently, if
it
ſeem inconvenient to admit an Elaſtical
1power in the Water, it may be ſaid that
the
ſwelling of the compreſſ'd Water in
the
Pewter Veſſel lately mention'd, and
the
ſpringing up of the Water at the hole
made
by the Needle, were not the effects
of
any internal Elater of the Water, but
of
the ſpring of the many little particles
of
Air diſperſ'd through that Water, and
acting
upon it in their ſudden recovering
themſelves
to a greater extent, then that
to
which a violent compreſſion had re­
duc
'd them.
But though, from all theſe particulars,
it
ſeems manifeſt that the bubbles we have
been
all this while treating of, were pro­
duc
'd by ſuch a ſubſtance as may be pro­
perly
enough call'd Air; yet till we ſhall
have
had the opportunity of making
ſome
further tryals concerning the nature
of
the Air, we ſhall not reſolutely deter­
mine
whether or no Air be a Primogenial
Body
(if I may ſo ſpeak) that cannot
now
be generated or turn'd either into
Water
or any other Body.
Yet in the
mean
while (becauſe it is an important
Queſtion
, and if rightly determin'd, may
much
conduce to the knowledge of the
1nature of the Air) We think it not unfit
to
make a brief mention of ſome of the
particulars
which at preſent occur to our
thoughts
in favor of either part of the
Queſtion
.
Firſt then, divers Naturaliſts eſteem the
Air
(as well as other Elements) to be in­
generable
and incorruptible.
And reaſons
plauſible
enough may be drawn to coun­
tenance
this Opinion from the conſidera­
tion
of that permanency that ought to
belong
to the corporeal Principles of
ther
Bodies.
Next, Experience may be pleaded to
the
ſame purpoſe, for I have read of ſome
who
have in vain attempted to turn Air
into
Water, or VVater into Air.
The diligent Schottus tells us, That

mongſt
the other rarities to be met with
in
that great Repoſitory of them, the
Muſæum Kercherianum, there is a round
Glaſs
with a tapering Neck near half full
(as one may gueſs by the Scheme he an­
nexes
) of ordinary Spring-water, which
having
been Hermetically ſhut up there
by
Clavius the famous Geometrician,
The
included water is to this day pre­
ſerv
'd, not onely clear and pure, as if
it
were but newly put in: But (as it ſeems)
1without (in the leaſt) turning into Air,
notwithſtanding
its having been kept
there
theſe fifty years: For he tells us,
That
the Water hath continued there all
this
while without any diminution.
Schottus

Part
3.
Claſſ
.
1.
Nor does it appear in thoſe Glaſſes,
which
for Chymical Experiments we uſu­
ally
cloſe with Hermes his Seal (as they
call
it) that the included Air does, during
its
long Impriſonment, notwithſtanding
the
alteration it receives from various de­
grees
of heat, diſcernably alter its nature.
Whereas we plainly perceive in our Dige­
ſtions
and Diſtillations, that though it
may
be rarified into inviſible Vapors, yet
it
is not really chang'd into Air, but onely
divided
by heat, and ſcatter'd into very
minute
parts, which meeting together in
the
Alembick or in the Receiver, do pre­
ſently
return into ſuch Water as they con­
ſtituted
before.
And we alſo ſee, that
ev
'n Spirit of Wine, and other ſubtle and
fugitive
Spirits, though they eaſily fly in­
to
the Air, and mingle with it, do yet in
the
Glaſſes of Chymiſts eaſily lay aſide
the
diſguiſe of Air, and reſume the deve­
ſted
form of Liquors.
And ſo volatile
Salts
, as of Urine, Harts-horn, &c. though
they
will readily diſperſe themſelves
1through the Air, and play up and down in
the
capacity of an Alembick or a Recei­
ver
: yet will they, after a while, faſten
themſelves
to the inſides of ſuch Glaſſes
in
the form of Salts.
Beſides, ſince Air is confeſſedly en­
dow
'd with an Elaſtical power that proba­
bly
proceeds from its Texture, it appears
not
what it is that in ſuch light alterations
of
Water, as are by many preſum'd ca­
pable
of turning it into Air, can be rea­
ſonably
ſuppoſ'd ſo to contrive the Parti­
cles
of Water, as to give them, and that
permanently
, the ſtructure requiſite to a
Spring
.
I adde the word, Permanently,
becauſe
the newly mention'd obſervations
ſeem
to argue the Corpuſcles of Air to
be
irreducible into Water, whereas the
Aqueous
Particles may perhaps for a
while
be ſo vehemently agitated, as to
preſs
almoſt like Springs upon other Bo­
dies
; yet upon the ceaſing of the agitati­
on
, they quickly, by relapſing into Wa­
ter
, diſcloſe themſelves to have been no­
thing
elſe whil'ſt they counterfeited the
Air
.
Laſtly, The Experiment formerly made
in
our Engine with a piece of Match,
ſeems
to evince, that even thoſe light and
1ſubtle Fumes (for the moſt part not aque­
ous
neither) into which the Fire it ſelf
ſhatters
dry Bodies, have no ſuch Spring
in
them as the Air, ſince they were unable
to
hinder or repreſs the expanſion of the
Air
included in the Bladder they ſurroun­
ded
.
I remember indeed that the Learned

Foſephus Acoſta, in his Hiſtory of the
Weſt Indies, tells us, That he ſaw in thoſe
parts
ſome Grates of Iron ſo ruſted and
conſum
'd by the Air, that the Metal be­
ing
preſſ'd between the Fingers, diſſolv'd
(to uſe his words) to powder, as if it had
been
Hay or parched Straw.
And I re­

member
too, that the accurate Varenius
tells
us, That in the Iſlands commonly
called
Azores, the Air (and Wind) is ſo
ſharp
, that in a ſhort time it frets not only
Iron
Plates, but the very Tiles upon the
Roofs
of Houſes, and reduces them to
duſt
.
And I have elſewhere mention'd
ſome
recent Obſervations of this kinde.
But it may be ſaid, That the above-men­
tion
'd Authors aſcribe the recited effects
chiefly
to the Winds, and that however
the
corroſion of the Iron and the Tiles
may
proceed not from the Air it ſelf, or
any
of its genuine parts, but from ſome
1ſaline Corpuſcles diſperſ'd through the
Air
, and driven by the Winds againſt the
Bodies
it is preſum'd to fret.
And that
ſuch
volatile Salts may copiouſly aſcend
into
the Air, and yet retain their Nature,
as
doth the more fixt Salt in the Sea Wa­
ter
, the ſublimations of Sal-Armoniack
may
ſufficiently evince.
Not to mention
that
I have ſhown ſome Friends a ſecret
kinde
of ſaline Subſtance incomparably
ſubtler
then Sal-Armoniack, which did
not
onely eaſily enough aſcend it ſelf, but
carried
up with it (and that in a very great
proportion
) the ſolid and ponderous Bo­
dy
ev'n of uncalcin'd Gold in the form of
ſubtle
exhalations, which did afterwards
faſten
themſelves to the upper parts of
the
Veſſels, and yet manifeſt themſelves
to
continue Gold.
We remember alſo,
that
to try whether Water could be turn'd
into
Air, we once took an Æolipile, into
which
we had before convey'd ſome Wa­
ter
, and placing it upon kindled Coals
when
the heat forc'd out a vehement
ſtream
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 Æolipile after a while to blow up
the
Bladder, we carefully ty'd it again
1that the included ſubſtance might not get
away
.
Then ſlipping it off from the Æo­
lipile
we convey'd it into our Receiver, to
try
whether or no that which in part di­
ſtended
the Bladder would appear by its
Spring
to be true Air: whereby we found
that
upon the exſuction of the ambient
Air
, the included ſubſtance expanded it
ſelf
and the Bladder to a very much great­
er
bulk then it was of before.
And for
further
ſatisfaction, having again taken
out
the Bladder, we ſuffer'd it to remain
ty
'd up till next morning, to try whether
time
, and the coldneſs of the night, would
make
the contain'd ſubſtance relapſe in­
to
Water: But the next Morning we
found
it little leſs tumid then before.
I
remember
, I ſay, that I once made this
Experiment
; but I might ſay in anſwer
to
it, that the chief reaſon of my men­
tioning
it, is, To let Your Lordſhip ſee
how
requiſite it is to be circumſpect and
conſiderate
, when we are to make and to
build
upon nice Experiments.
For though
I
may ſeem to have uſed ſufficient cauti­
on
, yet afterward conſidering with my
ſelf
that the Æolipile I had imploy'd was
a
very large one, and that it required much
more
care then one that has not try'd it
1would imagine, to drive out all the Air
from
a large Æolipile, I eaſily ſuſpected
that
the diſtenſion of the Bladder in our
pneumatical
Veſſel, might proceed not
from
the Watery ſteams that came out at
the
narrow mouth of the Æolipile, and
had
very much wetted the Bladder, but
from
the rarified Air which in that ſort of
Veſſels
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
ſon
of the ſhrinking of the Bladders (up­
on
their being heated) and of other impe­
diments
) to make it ſo accurately as to de­
duce
from it, that Water may be rarified
into
true Air.
Natural &
Hiſt.
In­
, Lib. 3.
9.
Geogr. Ge­
ral. Lib.
19.
Againſt the four other above-mention'd
Conſiderations
, we cannot ſpend time to
frame
Objections, but muſt forth with
proceed
to the mention of thoſe things
that
ſeem to argue that Air (at leaſt ſuch
as
produc'd our bubbles) maybe gene­
rated
of Water and other Bodies.
Firſt then we have found by Experi­
ence
that a vapid Air, or Water rarified
into
vapor, may at leaſt for a while emu­
late
the elaſtical power of that which is
generally
acknowledg'd to be true Air.
1For if you take a good Æolipile, with a
moderately
ſtrong and ſlender Neck, and
filling
it with Water, lay it upon quick
Coals
, you may after a while obſerve ſo
great
a preſſure by ſome of the parts con­
tain
'd in the Æolipile upon others, that
the
Water will ſometimes be thrown up
into
the Air above three or four Foot
high
; and if you then take the Æolipile
almoſt
red hot from off the Fire, you may
perceive
that the Water will for a longer
time
then one would eaſily imagine con­
tinue
to be ſpouted out in a violent
Stream
.
And if there remains but little
Water
in the Æolipile 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 ſuck in ſome
Water
, there will be made from time to
time
ſtore of large bubbles in that Water
where
into the neck was plunged.
Which
bubbles
ſeem manifeſtly to proceed from
hence
, that for a while the heat in the Æ­
olipile
continues ſtrong enough to rarifie
part
of the Water that is ſuck'd in, and
expel
it in the form of Vapors through
the
Water incumbent on the Pipe.
If al­
ſo
when the Æolipile is almoſt full of wa­
ter
, and therefore can contain but little
1Air; you hold a Coal or Brand in that
ſtream
of Vapors that iſſues out of the
narrow
mouth of it, you will finde this
vapid
or rorid Air, (if I may ſo call it)
to
blow the Fire very ſtrongly and with a
roaring
noiſe.
And that it be not ſaid
that
'tis by the external Air which the
queous
ſteams drive before them, and
not
by the Steams themſelves, that the
Blaſt
is made and the Flame excited; it
has
been obſerv'd, that by approaching
the
Coal or Brand almoſt to the mouth
of
the Æolipile, the winde appear'd more
vehement
then if the Body to be kindled
were
held ſome Inches off.
But in regard the elaſtical power of the
Stream
, iſſuing out of an Æolipile, ſeems
manifeſtly
due to the heat that expands
and
agitates the aqueous Particles where­
of
that Stream conſiſts, and that ſuch
rapid
winds ſeem to be but water ſcatter'd
into
little parts and ſet a moving; ſince
we
finde, that holding a Knife, or any
ſolid
, ſmooth and cloſe Body againſt the
ſtream
that iſſues out of the Æolipile, the
vapors
condenſing upon it, will preſently
cover
it with water: It will be very per­
tinent
to ſubjoyn a notable Experiment
that
I remember I have met with in the
1deſcription given us by the Induſtrious
Kircher, of ſeveral Muſical Engines. And
(though it may ſeem ſomewhat prolix)
we
will recite what he delivers in his own
words
, which are theſe.
Cum codem tempore quo hæc ſcripſi

ſummi Pont: Innocentii Xmi mandato or­
gani
hydraulici in horto Quirinali conſti­
tuendi
cur a mihi commendata eſſet; Æoliam
camer
am inſigni ſane ſucceſſu conſtrui juſsi­
mus
, quæ ſequitur ratione.
Kirch: Art:
Mag
: Con:
& Diſſon:
lib
. 9.
p
. 309.
Erat longitudo ſive altitudo cameræ AH
5
Pedum, Latitudine 3 fere ex lateribus

conſtructa; in medio duo tenebat Diaphrag­
mata
CD & EJ in modum cribri pluri­
bus
for aminibus pertuſa.
Paulo infra ca­
nalis
G aquam advehens inſerebatur in H
eidem epiſtomium par ab at exitum. Aqua
it
áque per canalem G maximo impetu ruens
vehementiſsimum
ventum mox intus exci­
t
ab at; qui ventus nimia humiditate imbu­
tus
, ut purior exiret ſiccior〈qué〉, Diaphrag­
mata
ill a in cribri modum pertuſa, or dinata
ſunt
.
Intra hæc enim aquæ vehemens agi­
tatio
rupta fracta〈qué〉 aerem puriorem per A
canalem ſubtilioremque emittebat: Verum
cum
poſtea inventum ſit aerem plus æquo humi­
dum
interioribus Organi meatibus maximum
detrimentum
inferre: Hinc ut aer aquoſus
1ſicciſsimam conſiſtentiam acquireret, ordina­
vimus
canalem plumbeum QR in helicem
contortum
vaſi S aliquantulum capaciori in
modum
Urnæ efformato, inſertum.
Intra
urnam
enim plumbeam & canalem tortuo­
ſum
illiſus aer humidus, it a ab omni aquoſi­
tate
defæcabatur, ut ex furno in Organum
derivatus
dici potuerit.
Urna S canalis
tortuoſus
QR ultimum orificium Q inſe­
ritur
anemothecæ organi.
Et hunc modum
organis
hydraulicis omnium aptiſsimum reperi.
See the fif­
teenth
Fi­
gure
.
Debet autem cameræ illa ſituari in loco
quantum
fieri poteſt ſicciori it a ut longo ca­
nali
aqua intr a eam derivetur ne locus hu­
miditate
ſua Organis officiat.
Thus far the Ingenious Kircherus, whom
I
the rather cite, becauſe although I have
been
informed of divers Ventiducts (as
they
call them) by very knowing Tra­
vellers
that have obſerv'd them: Yet this
relation
of our Author being very pun­
ctual
, and deliver'd upon his own particu­
lar
Experience, has, I confeſs, made me
wiſh
I had had the good fortune when I
was
at Rome, to take notice of theſe Or­
gans
; or that I had now the opportunity
of
examining of ſuch an Experiment.
For if upon a ſtrict inquiry I ſhould find
that
the breath that blows the Organs
1does not really upon the ceaſing of its un­
uſual
agitation by little and little relapſe
into
water, I ſhould ſtrongly ſuſpect that
'tis poſſible for Water to be eaſily turn'd
into
Air.
I remember indeed, that we
have
formerly taught that there lurks an
interſperſed
Air in the pores of ordinary
Water
, which may poſſibly be ſtruck out
by
the breaking of the Water in its fall
into
the Æolian Chamber, (as he calls it.)
But
in regard the Scheme ſeems to repre­
ſent
that Chamber as cloſely ſhut, and
thereby
forbids us to ſuppoſe that any Air
is
carried into it but what is latitant in the
Water
, it will ſcarce ſeem probable to
him
who remembers how ſmall a propor­
tion
of Air, that appear'd to be when its
rarification
ſeaſed, which was conceal'd in
the
Water we freed from bubbles in our
Receiver
, that ſo little Air as is common­
ly
diſperſ'd through Water, ſhould be
ble
, in ſo little Water as was requiſite for
ſo
ſmall a room, to make ſo vehement a
Wind
as our Author here tells us of.
I
have
ſometime therefore ſuſpected, that
in
this caſe the Wind may be produc'd by
ſmall
particles of the water it ſelf, forci­
bly
expell'd out of the Chamber into the
Organs
.
And to the Objection to which
1I foreſaw this gheſs to be liable, namely,
That
, no heat intervening, there appear'd
nothing
that ſhould raiſe the Water into
exhalations
and give them an impulſe.
I
thought
it might be ſaid that motion
lone
, if vehement enough, may, with­
out
ſenſible heat, ſuffice to break Water
into
very minute parts, and make them aſ­
cend
upwards, if they can no where elſe
more
eaſily continue their agitation.
For
Iremember
, that Travelling betwixt Ly­
ons
and Geneva, I ſaw, not very far out of
the
Way, a place where the River of
Rhone coming ſuddenly to be ſtreighten'd
betwixt
two Rocks, ſo near each other,
that
a Man may (if my Memory fail me
not
) ſtand aſtride upon both at once: that
rapid
Stream daſhing with great impetuo­
ſity
againſt its Rocky Boundaries, does
break
part of its Water into ſuch minute
Corpuſcles
, and put them into ſuch a mo­
tion
, that Paſſengers obſerve at a good di­
ſtance
off, as it were a Miſt ariſing from
that
place, and aſcending a good way up
into
the Air.
Such, I ſay, was my ſuſ­
picion
touching the Wind we have been
conſidering
, but it ſeems ſomething odde
that
aqueous Vapors ſhould, like a dry
Wind
, paſs through ſo long and tortu-
1ous a Pipe of Lead, as that deſcrib'd by
our
Author, ſince we ſee in the Heads of
Stills
, and the Necks of Æolipiles, how
quickly
ſuch vapors are even by a very lit­
tle
cold recondenſed into Water.
But
to
this alſo ſomething may be ſpeciouſly
reply
'd; wherefore contenting my ſelf to
have
mention'd our Authors Experiment
as
a plauſible, though not demonſtrative
proof
, that Water may be tranſmuted in­
to
Air.
We will paſs on to mention in
the
third place another Experiment, which
we
try'd in order to the ſame enquiry.
We took a clear Glaſs bubble (capable
of
containing by gheſs about three Oun­
ces
of Water) with a Neck ſomewhat
long
and wide, of a Cylindrical form;
this
we fill'd with Oyl of Vitriol and fair
water
, of each almoſt a like quantity, and
caſting
in half a dozen ſmall Iron Nails,
we
ſtopt the mouth of the Glaſs (which
was
top-full of Liquor) with a flat piece
of
Diapalma provided for the purpoſe,
that
accommodating it ſelf to the ſurface
of
the water, the Air might be exqui­
ſitely
excluded: and ſpeedily inverting
the
Viol, we put the Neck of it into a
ſmall
wide-mouth'd Glaſs that ſtood rea­
dy
with more of the ſame Liquor in it, to
1receive it. As ſoon 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 bigneſs of
a
Pea, which ſeem'd rather to conſiſt of
ſmall
and recent bubbles, produc'd by the
action
of the diſſolving Liquor upon the
Iron
, then any parcel of the external Air
that
might be ſuſpected to have got in
upon
the inverſion of the Glaſs, eſpeci­
ally
ſince we gave time to thoſe little
Particles
of Air which were carried down
with
the Nails into the Liquor to fly up
again
.
But whence this firſt bubble was
produced
, is not ſo material to our Expe­
riment
, in regard it was ſo ſmall: For
ſoon
after we perceiv'd the bubbles
produced
by the action of the Men­
ſtruum
, upon the Metal aſcending co­
piouſly
to the bubble already named, and
breaking
into it, did ſoon exceedingly in­
creaſe
it, and by degrees depreſs the wa­
ter
lower and lower, till at length the ſub­
ſtance
contain'd in theſe bubbles poſſeſſed
the
whole cavity of the Glaſs Viol, and
almoſt
of its Neck too, reaching much
lower
in the Neck then the ſurface of the
ambient
Liquor, wherewith the open­
mouth
'd Glaſs was by this means almoſt
1repleniſhed. And becauſe it might be
ſuſpected
that the depreſſion of the Li­
quor
might proceed from the agitation
whereinto
the exhaling and impriſon'd
ſteams
were put, by that heat which is
wont
to reſult from that action of corro­
ſive
ſalts upon Metals, we ſuffered both
the
Viol and the open-mouthed Glaſs to
remain
as they were, in a Window, for
three
or four days and nights together; but
looking
upou them ſeveral times during
that
while, as well as at the expiration of
it
, the whole cavity of the Glaſs bubble,
and
moſt of its Neck, ſeem'd to be poſ­
ſeſſ
'd by Air, ſince by its ſpring it was
ble
for ſo long to hinder the expell'd and
ambient
Liquor from regaining its former
place
.
And it was remarkable, that juſt
before
we took the Glaſs bubble out of
the
other Glaſs, upon the application
of
a warm hand to the convex part of the
bubble
; the Impriſon'd ſubſtance readily
dilated
it ſelf like Air, and broke through
the
Liquor in divers bubbles, ſucceeding
one
another.
Having alſo another time try'd the like
Experiment
with a ſmall Viol, and with
Nails
diſſolv'd in Aquafortis, we found
nothing
incongruous to what we have
now
deliver'd.
And this Circumſtance
1we obſerv'd, that the newly generated
ſteams
did not onely poſſeſs almoſt all the
whole
cavity of the Glaſs, but divers
times
without the aſſiſtance of the heat of
my
hand, broke away in large bubbles
through
the ambient Liquor into the
pen
Air: So that theſe Experiments
with
corroſive Liquors, ſeem'd manifeſt­
ly
enough to prove, though not that Air
may
be generated out of the Water, yet
that
in general air may be generated anew.
Laſtly, to the foregoing Arguments
from
Experience we might eaſily ſubjoyn
the
Authority of Ariſtotle, and of (his
followers
) the Schools who are known to
have
taught, that Air and Water being
Symbolizing
Elements (in the quality of
moiſture
) are eaſily tranſmutable into one
another
.
But we ſhall rather to the fore­
going
Argument adde this, drawn from
Reaſon
, That if, as Leucippus, Democri­
tus
, Epieurus and others, follow'd by
divers
modern Naturaliſts, have taught,
the
difference of Bodies proceeds but
from
the various Magnitudes, Figures,
Motions
, and Textures of the ſmall
parts
they conſiſt of, (all the quali­
ties
that make them differ, being de­
ducible
from thence) there appeares
1no reaſon why the minute parts of Wa­
ter
, and other Bodies, may not be ſo agi­
tated
or connected as to deſerve the name
of
Air.
For if we allow the Carteſian
Hypotheſis
, according to which, as we no­
ted
at the beginning of this Letter, the
Air
may conſiſt of any terrene or aqueous
Corpuſcles
, provided they be kept ſwim­
ming
in the interfluent Celeſtial Matter;
it
is obvious that Air may be as often ge­
nerated
, as Terreſtrial Particles minute
enough
to be carried up and down, by the
Celeſtial
Matter aſcend into the Atmo­
ſphere
.
And if we will have the Air to
be
a congeries of little ſlender Springs, it
ſeems
not impoſſible, though it be diffi­
cult
, that the ſmall parts of divers Bo­
dies
may by a lucky concourſe of cauſes
be
ſo connected as to conſtitute ſuch
little
Springs, ſince (as we note in another
Treatiſe
) Water in the Plants it nouriſhes
is
uſually contriv'd into Springy Bodies,
and
even the bare alter'd poſition and con­
nexion
of the parts of a Body may ſuf­
fice
to give it a Spring that it had not be­
fore
, as may be ſeen in a thin and fiexible
Plate
of Silver; unto which, by ſome
ſtroaks
of a Hammer, you may give a
Spring
, and by onely heating it red hot
1you may make it again flexible as be­
fore
.
Theſe, My Lord, are ſome of the
Conſiderations
at preſent occurring to
my
thoughts, by which it may be made
probable
that Air may be generated
new
.
And though it be not impoſſible
to
propoſe Objections againſt theſe, as
well
as againſt what has been repreſented
in
favor of the contrary Doctrine; yet
having
already almoſt tyr'd my ſelf, and
I
fear more then almoſt tyr'd Your Lord­
ſhip
with ſo troubleſome an Enquiry af­
ter
the Nature of bubbles, I ſhall wil­
lingly
leave Your Lordſhip to judge of
the
Arguments alledged on either ſide,
and
I ſhould ſcarce have ventur'd to enter­
tain
You ſo long concerning ſuch empty
things
as the Bubbles, which have occa­
ſion
'd all this Diſcourſe, but that I am
willing
to invite You to take notice with
me
of the obſcurity of things, or the dim­
neſs
of our created Intellects (which yet
of
late too many ſo far preſume upon, as
either
to Deny or Cenſure the Almighty
and
Omniſcient Creator himſelf) and to
learn
hence this Leſſon, That there are
very
many Things in Nature that we diſ­
dainfully
over-look as obvious or deſpi-
1cable, each of which would exerciſe our
Underſtandings
, if not poſe them too, if
we
would but attentively enough conſider
it
, and not ſuperficially contemplate, but
attempt
ſatisfactorily to explicate the na­
ture
of it.
SInce the writing of the twenty one and

twenty
ſecond Experiments (and not­
withſtanding
all that hath been on their
occaſion
deliver'd concerning bubbles) we
made
ſome further tryals in proſecution
of
the ſame inquiry whereto they were
deſigned
.
Experi­
ment
23.
We choſe then, amongſt thoſe Glaſſes
which
Chymiſts are wont to call Philoſo­
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 gheſt, almoſt an Inch at the bot­
tom
; which breadth we pitch'd upon for
a
reaſon that will by and by appear: then
filling
it with common Water to the
height
of about a Foot and a half, ſo
that
the upper part remain'd empty, we
ſhut
it into the Receiver, and watch'd what
would
follow upon pumping, which pro-
1ved that a great part of the Air being
drawn
out, the bubbles began to diſcover
themſelves
at the bottom and ſides of the
Glaſs
; and increaſing, as the Air was
more
and more drawn away, they did
from
time to time aſcend copiouſly
nough
to the top of the Water, and there
quickly
break: but by reaſon that the
wideneſs
of the Glaſs allow'd them free
paſſage
through the Water, they did not
appear
as in the former Experiments to
make
it ſwell: The Water ſcarce ever ri­
ſing
at all above the mark affixt to its up­
per
ſurface when it was put in, and upon
the
return permitted to the outward Air,
and
conſequently the ſhrinking in of the
remaining
bubbles, the Water ſeem'd to
have
loſt of its firſt extent, by the avo­
lation
of the formerly interſperſ'd Air.
Being willing likewiſe to try whether
diſtilled
Water were by having been di­
vided
into minute parts, and then re-uni­
ted
, more or leſs diſpoſ'd to expand it
ſelf
then Water not diſtill'd: We took
out
of our Laboratory ſome careful­
ly
diſtill'd Rain-water, and put about
two
Ounces of it into a round Glaſs
1bubble with a very ſmall Neck (not ex­
ceeding
the ſixth 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 iſſue was, That though we drew
out
more then ordinary, yet there ap­
pear
'd not the leaſt intumeſcence of the
Water
, nor any aſcending bubbles.
But ſuſpecting that either the ſmall
quantity
of the water or the Figure of the
Veſſel
might have an intereſt in this odde
Phænomenon, we took the lately mention'd
Philoſophical
Egge, and another not
much
differing from it; the former we
fill
'd up with diſtill'd Rain-water to the
old
mark, and into the latter we put a
long
Cylinder or Rod of ſolid Glaſs to
ſtreighten
the cavity of the Neck by al­
moſt
filling it up; and then pouring ſome
diſtilled
Water into that alſo, till it
reach
'd within ſome Fingers breadth of
the
top, the Eggs were let down into the
Receiver
.
In this Experiment the Air
was
ſo far drawn forth before there ap­
pear
'd any bubble in either of the Glaſſes,
that
the diſparity betwixt this and com­
mon
water was manifeſt enough.
But at
length
, when the Air was almoſt quite
pump
'd out, the bubbles began to diſ-
1cloſe themſelves, and to increaſe as the
preſſure
of the Air in the Receiver de­
creaſ
'd.
But whereas in the firſt men­
tion
'd Philoſophical Egge the bubbles
were
very ſmall, and never able to ſwell
the
Water, that we took notice of, at all
above
the mark: In the other, whoſe
Neck
, as we lately ſaid, was ſtraightned,
and
their paſſage obſtructed, great num­
bers
of them, and bigger, faſtned them­
ſelves
to the lower end of the Glaſs ram­
mer
(if we may ſo call it) and gather'd in
ſuch
numbers between that and the ſides
of
the Neck, that the Water ſwell'd
bout
a Fingers breadth above the mark,
though
upon the admitting of the exter­
nal
Air it relapſ'd to the former mark, or
rather
fell ſomewhat below it.
And al­
though
thereupon in the firſt nam'd Veſ­
ſel
all the bubbles preſently diſ-appear'd,
yet
in the other we obſerv'd, that divers
remained
faſtned to the lower part of the
Glaſs
rammer, and continued there ſome­
what
to our wonder, for above an hour
after
, but contracted in their Dimen­
ſions
.
Moreover, having ſuffered the Glaſſes
to
remain above twenty four hours in the
1Receiver, we afterwards repeated the Ex­
periment
, to try what change the exſucti­
on
of the external Air would produce in
the
Water, after the internal and latitant
Air
had (as is above recited) in great mea­
ſure
got away in bubbles, and whether or
no
the Water would by ſtanding re-admit
any
new particles of Air in the room of
thoſe
that had forſaken it.
But though
we
exhauſted the Receiver very diligent­
ly
, yet we ſcarce ſaw a bubble in either
of
the Glaſſes; notwithſtanding which,
we
perceiv'd the Water to riſe about the
breadth
of a Barly-corn, or more, in the
Neck
of that Glaſs wherein the ſolid Cy­
linder
had been put; The Liquor in the
other
Glaſs not ſenſibly ſwelling.
And laſtly, upon the letting in of the
Air
, the Water in the ſtraightned Neck
ſoon
ſubſided to the mark above which
it
had ſwollen, which whether it ought
to
be aſcrib'd to the ſame ſmall expanſion
of
the parts of the Water it ſelf, or to
the
rarifaction of ſome yet latitant Air
broken
into ſuch ſmall particles, as to
ſcape
our obſervation, ſeems not eaſily
determinable
, without ſuch further tryals,
as
would perhaps prove tedious to be re­
cited
as well as to be made; though I was
1content to ſet down thoſe already men­
tion
'd, that it might appear how requi­
ſite
it is in nice Experiments to conſider
variety
of Circumſtances.
AFter having thus diſcover'd what ope­

ration
the exſuction of the ambient
Air
had upon Water, we thought good
to
try alſo what changes would happen in
other
Liquors upon the like taking off the
preſſure
of the external Air.
We took
then
a Glaſs Egge, ſomewhat 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 incloſ'd it in the Re­
ceiver
together with common Water in
a
reſembling Veſſel, that we might the
better
compare together the operation of
the
exſuction of the Air upon thoſe two
Liquors
.
The Pump being ſet a work there
began
to appear bubbles in the Oyl much
ſooner
then in the Water, and afterwards
they
alſo aſcended much more copiouſly
in
the former Liquor then the latter: Nay,
and
when by having quite tired the Pum­
per
, and almoſt our own patience, we
1gave over, the bubbles riſe almoſt (if
not
altogether) in as great numbers
as
ever, inſomuch as none of the various
Liquors
we tryed either before or ſince,
ſeem
'd to abound more with Aerial Parti­
cles
then did this Oyl.
In which it was
further
remarkable, that between the time
it
was ſet into the Receiver, and that at
which
we could get ready to Pump, it ſub­
ſided
notably (by gheſs about half an
Inch
) below the mark it reach'd before it
was
put in.
Experi­
ment
24.
After this expreſſ'd Oyl, we made tryal
of
a diſtill'd one, and for that purpoſe
made
choice of the common Oyl or Spi­
rit
(for in the Shops where it is ſold, the
ſame
Liquor is promiſcuouſly call'd by ei­
ther
name) of Turpentine; becauſe 'twas
onely
of that Chymical Oyl, we had a
ſufficient
quantity: which, being put in­
to
a ſmall Glaſs bubble with a ſlender
Neck
, ſo as to fill it to about two Inches
from
the top, did, upon the evacuating
of
the Receiver, preſent us with great
ſtore
of bubbles; moſt of which riſing
from
the bottom, expanded themſelves
exceedingly
in their aſcent, and made the
Liquor
in the Neck to ſwell ſo much by
degrees
, that at length it divers times ran
1over at the top: by which means, we
were
hindred from being able to diſcern
upon
the letting in of the Air, how much
the
ſubſidence of the Oyl below the firſt
mark
was due to the receſs of the bub­
bles
.
Having likewiſe a minde to try whe­
ther
as ſtrong a ſolution of Salt of Tartar
in
fair Water as could be made (we ha­
ving
then no Oyl of Tartar per deliqui­
um
at hand) though it be accounted,
Quick-ſilver
excepted, the heavieſt of
Liquors
would afford us any bubbles; we
put
in a Glaſs Egge full of it at the ſame
time
, with other Liquors, and found that
they
did long yield ſtore of bubbles be­
fore
any diſcovered themſelves in the
Liquor
of Tartar; and having purſued
the
Experiment, it appear'd, That of all
the
Liquors we made tryal of, this afford­
ed
the feweſt and the ſmalleſt Bubbles.
Spirit of Vinager being try'd after the
ſame
manner, exhibited a moderate num­
ber
of bubbles, but ſcarce any thing elſe
worth
the mentioning.
Nor could we in red Wine, try'd in a
Glaſs
Egge, take notice of any thing ve­
ry
obſervable.
For though upon the ex­
ſuction
of the Air the bubbles aſcended
1in this Liquor, as it were in ſholes,
and
ſhifted places among themſelves in
their
aſcent; yet the Intumeſcence of the
whole
bulk of the Liquor was ſcarce at all
ſenſible
, the bubbles moſt commonly
breaking
very ſoon after their arrival at
the
top, where during their ſtay, they
compoſ
'd a kinde of ſhallow froth, which
alone
appear'd higher in the Neck of the
Glaſs
, then was the Wine when it was
firſt
let down.
Neither yet did Milk, con­
vey
'd into our Pneumatical Veſſel, pre­
ſent
us with any thing memorable, ſave
that
(as it ſeem'd by reaſon of ſome un­
ctuouſneſs
of the Liquor) the bubbles
not
eaſily breaking at the top, and thruſt­
ing
up one another made the intumeſcence
appear
much greater then that of common
Water
.
We likewiſe convey'd Hens Eggs into
the
Receiver, but, after the exſuction 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 burſt, by freezing them
within
doors with Snow and Salt: The
Ice
, into which the aqueous parts of the
Egge
were turned by the cold, ſo diſtend-
1ing (probably by reaſon of the numerous
bubbles
wont to be obſervable in Ice) the
outward
parts of the Egge, that it uſually
crack
'd the ſhell, though the inner Mem­
brane
that involv'd the ſeveral Liquors
of
the Egge, becauſe it would ſtretch
and
yield, remain d unbroken, And here­
upon
we imagin'd that in our Engine it
might
appear whether or no there were
any
conſiderable Spring, either in any of
the
Liquors, or in any other more ſpiri­
tuous
ſubſtance included in the Egge.
We took alſo ſome Spirit of Urine,
careleſly
enough deflegmed, and put it in­
to
the ſame Glaſs (firſt carefully ſcowr'd
and
cleanſ'd) wherein we had put the Oyl­
olive
above mention'd: We took alſo an­
other
Glaſs, differing from a Glaſs Egge,
onely
in that its bottom was ſlat, 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.
We took alſo another Glaſs 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 ſame Spirit of Wine,
till
it reach'd about an Inch higher.
Theſe three Glaſſes having marks ſet
on
them, over againſt the edges of the
1contain'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 diſcloſ'd a
great
ſtore of bubbles, eſpecially towards
the
top; but ſcarce afforded us any thing
worth
remem bring.
The Spirit of Urine
appear
'd to ſwell near an Inch and an half
above
the mark; and beſides that, ſent
forth
ſtore of bubbles, which made a
kinde
of froth at the upper part of it.
And
above
that ſpume there appear'd eight or
ten
great bubbles one above another, in a
very
decent order, each of them conſtitu­
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 theſe bubbles reach'd
to
the top) ſeem'd to be divided into al­
moſt
equal parts, by certain Diaphrag­
mes
, conſiſting of the coats of the bub­
bles
, whoſe edges appear'd like ſo many
Rings
ſuſpended one above another.
In the Spirit of Wine there did ariſe a
great
multitude of bubbles, even till
wearineſs
did make us give over the Ex­
periment
.
And in theſe bubbles two or
three
things were remarkable; as firſt,
1That they aſcended with a very notable
celerity
: Next, That being arriv'd at the
top
, they made no ſtay there, and yet,
notwithſtanding
the great thinneſs and
ſpitituouſneſs
of the Liquor, did, before
they
broke, lift up the upper ſurface of
it
, and for a moment or two form thereof
a
thin film or skin which appear'd protu­
berant
above the reſt of the ſuperficies
like
a ſmall Hemiſphere.
Thirdly, That
they
aſcended ſtraight up, whereas thoſe
produc
'd at the lower part of the Veſſel,
containing
the mixture of the Water and
Spirit
of Wine, aſcended with a waver­
ing
or wrigling motion, whereby they
deſcrib
'd an indented Line.
Laſtly, It
was
obſervable 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 ſeem'd to riſe from cer­
tain
determinate places at the bottom of
the
Glaſs, but that in their aſcenſion they
kept
an almoſt equal diſtance from each
other
, and follow'd one another in a cer­
tain
order, whereby they ſeem'd part of
ſmall
Bracelets, conſiſting of equally lit­
tle
incontiguous Beads: the lower end of
each
Bracelet, being as it were, faſten'd to
a
certain point at the bottom of the Glaſs.
1
The Air being ſparingly let into the
Receiver
, the great bubbles formerly
mention
'd as incumbent upon one ano­
ther
, in that Glaſs that contain'd the Spi­
rit
of Urine, were by orderly degrees
leſſen
'd, till at length they wholly ſubſi­
ded
, notwithſtanding the receſs of ſo ma­
ny
bubbles as broke on the top of the
Spirit
of Urine, during all the time of the
Experiment
; yet it ſcarcely appear'd at all
to
be ſunk below the mark: Nor did the
mixture
of Spirit of Wine and Water
conſiderably
ſubſide.
But that is no­
thing
to what we obſerv'd in the Spirit
of
Wine, for not onely it conſpicuouſly
expanded
it ſelf in the Neck of the
Veſſel
that contain'd it, notwithſtand­
ing
the largeneſs of it; and that the
bubbles
were about to break at the
top
of it almoſt aſſoon as they arriv'd
there
: but upon the re-admiſſion of
the
external Air, the Spirit of Wine
retain
'd its newly acquired expanſion.
And though we let it alone for near
an
hour together, in expectation that it
might
ſubſide; yet when we took it
out
, we found it ſtill ſwell'd between a
quarter
and half an Inch above the
mark
; and although it was not eaſily
1imaginable how this Phænomenon could
proceed
from any miſtake in trying
the
Experiment, yet the ſtrangeneſſe
of
it invited me to repeat it with freſh
Spirit
of Wine; which, ſwelling in the
Neck
as formerly, I left all Night in
the
Receiver, allowing free acceſs to the
external
Air at the Stop-cock, and the
next
day found it ſtill expanded as be­
fore
, ſave that it ſeem'd a little lower:
which
decrement perhaps proceeded from
the
avolation of ſome of the fugitive
parts
of ſo volatile a Liquor.
And for
better
ſatisfaction having taken out the
Glaſs
, and conſider'd it in the open Air,
and
at a Window, I could not finde that
there
was any remaining Bubbles that
could
occaſion the perſevering and ad­
mir
'd expanſion.
BEing deſirous to diſcover what diffe­

rence
there might be as to gravity and
levity
, between Air expanded under Wa­
ter
, and it ſelfe before ſuch expanſion; we
took
two very ſmall Viols, ſuch as Chy­
mical
Eſſences (as they call them) are wont
to
be kept in, and of the ſize and ſhape ex­
preſſed
by the 8th Figure: into one of theſe
1we put ſo much of a certain ponderous
Mercurial
mixture (hapning to be then at
hand
) that the mouth being ſtopt with a
little
ſoft Wax, the Glaſs would juſt ſink
in
Water and no more; this we let fall to
the
bottom of a wide-mouth'd Cryſtal
Jar
, fill'd with about half a pint of com­
mon
Water, and into the ſame Veſſel we
ſunk
the other Eſſence Glaſs unſtopp'd,
with
as much Water in it as was more
then
ſufficient to make it ſubſide.
Both
theſe
ſunk 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 gheſſ'd to be of the
bigneſs
of half a Pea: This done, the
wide-mouth
'd Glaſs was let down into
the
Receiver, and the way of imploy­
ing
the Engine was carefully made uſe
of
.
Experi­
ment
25.
The ſucceſs was, That having drawn
out
a pretty quantity of Air, the bubbles
began
to diſcloſe themſelves in the Wa­
ter
, as in the former Experiments; and
though
for a good while after the bubbles
aſcended
in ſwarms from the lower parts
of
the Water, and haſtily broke at the
top
; yet we proſecuted the Experiment
ſo
long without ſeeing any effect wrought
1upon the Eſſence: Bottles, that we began
to
diſpair of ſeeing either of them riſe, but
continuing
to ply the Pump, that little
Glaſs
, whoſe 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 faſtned themſelves to
the
ſides of it; ſwimming thus with the
mouth
downward, we could eaſily per­
ceive
that the internal Air above men­
tion
'd had much delated it ſelf, and there­
by
ſeem'd to have contributed to the
merging
of the Glaſs, which remain'd
floating
, notwithſtanding the breaking
and
vaniſhing of moſt of the contiguous
bubbles
: being hereby incouraged to per­
ſiſt
in pumping, we obſerved with ſome
pleaſure
, that at each time we turn'd the
Key
, the Air in the little Glaſs did mani­
feſtly
expand it ſelf and thruſt out the wa­
ter
, generally retaining a very protuberant
ſurface
where it was contiguous to the re­
maining
Water.
And when after divers
exſuctions
of the Air in the Receiver,
that
in the little Viol ſo dilated it ſelf as
to
expel almoſt all the Water, it turn'd
up
its mouth towards the ſurface of the
Water
in the Jar, and there deliver'd a
large
bubble, and then relapſed into its
1formér floating poſture: 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 exhauſt our En­
gine
as much as it may be exhauſted: for
although
before the emerging of the ſmall
Viol
, we did (as has been touch'd alrea­
dy
) think we had very conſiderably em­
ptyed
the Receiver, becauſe there ſeem'd
to
come out but very little or almoſt
no
ſenſible Air at each exſuction into
and
out of the Cylinder; yet after­
wards
, at each drawing down the Suc­
ker
, the Air included in the Viol did
manifeſtly
dilate it ſelf, ſo long, that
it
did no leſs then nine times turn its
mouth
upwards, and diſcharge a bub­
ble
by conjecture about the bigneſs of
a
Pea, after the manner newly recited.
But as for that Violl which had the
weight
in it, it roſe not at all.
So
that
being not able by quick pumping
to
gain another bubble from the Air
in
the ſwimming Glaſs, which proceed­
ed
from ſome ſmall leak in the Veſſel,
though
it held in this Experiment more
ſtanch
then was uſual, we thought fit
to
let in leaſurely the Air from with­
out
, upon whoſe admiſſion that with-
1in the Viol ſhrinking into a very nar­
row
compaſs, the Glaſs did, as we expe­
cted
, fall down to the bottom of the
Jar
.
But being deſirous before we proceed­
ed
to any new.
Experiment, to try once
more
whether the little Glaſs that had
the
weight in it might not alſo be raiſ'd.
After we had ſuffer'd the Engine to re­
main
cloſ'd as it was, for five or ſix
hours
, the Pump was again ply'd with
ſo
much obſtinacy, that not onely
bout
the upper part of the Jar there ap­
pear
'd a good number of bubbles (but
very
much ſmaller then thoſe we ſaw
the
firſt time) but afterwards there
came
from the bottom of the Jar, bub­
bles
about the bigneſs of ſmal Peas: which
the
Pump being ſtill kept going, fol­
low
'd one another, to the number of forty,
coming
from the ſtopp'd Violl; whoſe
mouth
, it ſeems, had not been ſhut ſo
ſtrongly
and cloſely, but that the included
Air
, dilating it ſelf by its own ſpring, made
itſelf
ſome little paſſage betwixt the Wall
and
the Glaſs, and got away in theſe bub­
bles
; after which, the unſtopp'd Glaſs be­
gan
to float again, the Air ſhut up in it
1being manifeſtly ſo dilated as to expel a
good
part of the Water, but not ſo much
as
to break quite thorow.
And at length,
when
our expectation of it was almoſt ti­
red
out, the heavier of the two Viols be­
gan
to come aloft, and immediately to
ſubſide
again, which appear'd to be oc­
caſion
'd by the Air within it, whoſe bulk
and
ſpring being weaken'd by the receſs
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
Glaſs
, boyed it up towards the top, and
there
getting away, left it to ſink again
till
the preſſure of the Air in the Recei­
ver
being further taken off, the Air in the
Viol
was permitted to expand it ſelf 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 ceaſ'd from pumping;
yet
the Veſſel continuing more ſtanch
then
it was wont, this aſcent and fall of
the
Viol was repeated to the ninth time;
the
included Air, by reaſon of the ſmal­
neſs
of the vent at which it muſt paſs out,
being
not able to get away otherwiſe then
1little by little; and conſequently, in divers
ſuch
parcels as were able to conſtitute
bubbles
, each of them big enough to
raiſe
the Viol and keep it aloft until the
avolation
of that bubble.
Whereby it
may
appear, that the grand rule in Hy­
droſtaticks
, That a Body will ſwim in the
Water
, in caſe it be lighter then as much
of
that Water that equals it in bulk, will
hold
likewiſe when the preſſure of the At­
moſphere
is in very great meaſure, if not
when
it is totally taken off from the Li­
quor
and the Body: though it were worth
inquiring
what it is that ſo plentifully
concurs
to fill the bubbles made in our
Experiment
by the ſo much expanded
Air
, for to ſay with the old Peripatetick
Schools
, That the Air, in Rarefaction,
may
acquire a new extent, without the
admiſſion
of any new ſubſtance, would
be
an account of the Phænomenon very
much
out of date, and which, I ſuppoſe,
our
Modern Naturaliſts would neither
give
, nor acquieſs in.
I know not whether it may be requiſite
to
adde, that in this Experiment, as in
the
former, the outward Air being let in
did
ſoon precipitate the floating Viol.
But
I
think it will not be amiſs to note, that
1(congruouſly to what hath been above
recorded
of the vaſt expanſion of the Air)
the
Water which in the heavier Viol ſuc­
ceeded
in the room of thoſe forty odde, if
not
fifty great bubbles of Air, which at
ſeveral
times got out of it, amounted but
to
a very inconſiderable bigneſs.
IT having been obſerv'd by thoſe that

have
conſider'd what belongs to Pendu­
lums
(a Speculation that may, in my
poor
judgement, be highly uſeful to the
Naturaliſts
) that their Vibrations are
more
ſlowly made, and that their moti­
on
laſts leſs in a thicker, then in a thinner
Medium
: We thought it not amiſs to
try
if a Pendulum would ſwing faſter, or
continue
ſwinging longer in our Receiver,
in
caſe of the exſuction of the Air, then
otherwiſe
.
Wherefore we took a couple
of
round and poliſh'd Pendulums of Iron
or
Steel, of equal bigneſs, as near as we
could
get the Artificer to make them, and
weighing
each of them twenty Dragmes,
wanting
as many Grains.
One of theſe
we
ſuſpended in the cavity of the Recei­
ver
by a very ſlender ſilken ſtring, of
bout
ſeven Inches and a half in length
1from the cover of the Receiver to which
it
was faſten'd.
Then (by inclining the
Engine
) we made the Pendulum ſwing too
and
fro in it, and deſcrib'd as long Arches
as
in the capacity of ſo brittle a Veſſel we
thought
ſafe and convenient.
And one of
the
Aſſiſtants telling the recurſions of the
other
Pendulum hanging in the free Air,
by
a ſtring of about the ſame length, we
ſhorten
'd and lengthen'd this other Pen­
dulum
, till it appear'd to keep the ſame
pace
in its Vibrations, with that ſhut up in
the
Receiver.
Then having carefully
drawn
away the Air, we did again ſet the
Pendulum in the Receiver a vibrating;
and
giving the other Pendulum ſuch a mo­
tion
as made it deſcribe an Arch, accord­
ing
to ones gheſs, equal to that of the in­
cluded
Pendulum; we reckon'd, one of
us
, the Recurſions of that Pendulum which
was
ſwinging within the Receiver; and
another
of us that which was moving in
(that which one would think a much more
reſiſting
medinm) the Air. But once, one
of
us reckon'd near two and twenty Re­
curſions
of the included Pendulum, whilſt
the
other reckon'd but twenty of the Pen­
dulum
that vibrated without.
And an­
other
time alſo, the former of theſe Pen-
1dula was reckon'd to have made one and
twenty
Recurſions, wherein the other
made
but twenty: Yet this Experiment
ſeem
'd to teach us little, ſave that the dif­
ference
betwixt the motion of ſuch a Pen­
dulum
in the common Air, and in one ex­
ceedingly
rarified, is ſcarce ſenſible in
Veſſels
no bigger then our Receiver;
ſpecially
ſince though during this Expe­
riment
it held very well, yet we could
not
ſuppoſe it to be altogether devoid of
Air
.
We obſerv'd alſo, that when the
Receiver
was full of Air, the included
Pendulum continu'd its Recurſions about
fifteen
minutes (or a quarter of an hour)
before
it left off ſwinging; and that after
the
exſuction of the Air, the Vibration
of
the ſame Pendulum (being freſh put in­
to
motion) appear'd not (by a minutes
Watch
) to laſt ſenſibly longer.
So that
the
event of this Experiment being other
then
we expected, ſcarce afforded us any
other
ſatisfaction, then that of our not
having
omitted to try it.
And whether
in
caſe the tryal be made with a Pendulum
much
leſs diſproportionate to the Air then
Steel
is, the event will much better an­
ſwer
expectation, experience may be con­
ſulted
.
1
Experi­
ment
26.
THat the Air is the medium whereby
ſounds
are convey'd to the Ear, has

been
for many Ages, and is yet the com­
mon
Doctrine of the Schools.
But this
Received
Opinion has been of late op­
poſ
'd by ſome Philoſophers upon the ac­
count
of an Experiment made by the
Induſtrious
Kircher, and other Learned
Men
, who have (as they aſſure us) ob­
ſerv
'd, That if a Bell, with a Steel Clap­
per
, be ſo faſten'd to the inſide of a Tube,
that
upon the making the Experiment De
Vacuo
with that Tube, the Bell remain'd
ſuſpended
in the deſerted ſpace at the up­
per
end of the Tube: And if alſo a vi­
gorous
Load-ſtone be apply'd on the out­
ſide
of the Tube to the Bell, it will at­
tract
the Clapper, which upon the Remo­
val
of the Load-ſtone falling back, will
ſtrike
againſt the oppoſite ſide of the
Bell
, and thereby produce a very audible
ſound
, whence divers have concluded,
That
'tis not the Air, but ſome more ſub­
tle
Body that is the medium of ſounds.
But becauſe we conceiv'd that, to invali­
date
ſuch a conſequence from this ingeni­
ous
Experiment (though the moſt lucife-
1rous, that could well be made without
ſome
ſuch Engine as ours) ſome things
might
be ſpeciouſly enough alleadg'd; we
thought
fit to make a tryal or two, in or­
der
to the Diſcovery of what the Air does
in
conveying of ſounds, reſerving divers
other
Experiments tryable in our Engine
concerning
ſounds, till we can obtain more
leaſure
to proſecute them.
Conceiving it
then
the beſt way to make our tryal with
ſuch
a noiſe as might not be loud enough
to
make it difficult to diſcern ſlighter va­
riations
in it, but rather might be, both
laſting
, that we might take notice by what
degrees
it decreaſ'd; and ſo ſmall, that
it
could not grow much weaker with­
out
becoming imperceptible.
We took
a
Watch, whoſe Caſe we open'd, that
the
contain'd Air might have free egreſs
into
that of the Receiver.
And this Watch
was
ſuſpended in the cavity of the Veſſel
onely
by a Pack-thred, as the unlikelieſt
thing
to convey a ſound to the top of the
Receiver
: And then cloſing up the Veſ­
ſel
with melted Plaiſter, we liſten'd near
the
ſides of it, and plainly enough heard
the
noiſe made by the ballance.
Thoſe al­
ſo
of us, that watch'd for that Circum­
ſtance
, obſerv'd, that the noiſe ſeem'd to
1come directly in a ſtraight Line from the
Watch
unto the Ear.
And it was obſerva­
ble
to this purpoſe, that we found a mani­
feſt
diſparity of noiſe, by holding our Ears
near
the ſides of the Receiver, and near the
Cover
of it: which difference ſeem'd to
proceed
from that of the Texture of the
Glaſs
, from the ſtructure of the cover (and
of
the Cement) through which the ſound
was
propagated from the Watch to the
Ear
.
But let us proſecute our Experiment.
The Pump after this being imployd, it
ſeemd
that from time to time the ſound
grew
fainter and fainter; ſo that when the
Rec
iver was empty'd as much as it uſ'd
to
be for the foregoing Experiments, nei­
ther
we, nor ſome ſtrangers that chanc'd
to
be then in the room, could, by applying
our
Ears to the very ſides, hear any noiſe
from
within; though we could eaſily per­
ceive
that by the moving of the hand
which
mark'd the ſecond minutes, and by
that
of the ballance, that the Watch nei­
ther
ſtood ſtil, nor remarkably varied from
its
wonted motion.
And to ſatisfie our
ſelvs
further that it was indeed the abſence
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
1turn'd the Key and ſtopt the Valve, yet we
could
plainly hear the noiſe made by the
ballance
, though we held our Ears ſome­
times
at two Foot diſtance from the out­
ſide
of the Receiver.
And this Experi­
ment
being reiterated in another place,
ſucceded
after the like manner.
Which
ſeems
to prove, that whether or no the
Air
be the onely, it is at leaſt, the princi­
pal
medium of Sounds.
And by the way
it
is very well worth noting, that in a Veſ­
ſel
ſo well cloſ'd as our Receiver, ſo weak
a
pulſe as that of the ballance of a Watch
ſhould
propagate a motion to the Ear in a
Phiſically
ſtraight Line, notwithſtanding
the
interpoſition of ſo cloſe a Body as
Glaſs
, eſpecially Glaſs of ſuch thickneſs
as
that of our Receiver; ſince by this it
ſeems
that the air impriſon'd in the Glaſs,
muſt
, by the motion of the ballance, be
made
to beat againſt the concave part of
the
Receiver, ſtrongly enough to make
its
convex part beat upon the contiguous
Air
, and ſo propagate the motion to the
Liſtners
ears.
I know this cannot but
ſeem
ſtrange to thoſe, who, with an emi­
nent
Modern Philoſopher, will not allow
that
a Sound, made in the cavity of a
Room
, or other place ſo cloſ'd, that there
1is no intercourſe betwixt the external and
internal
Air, can be heard by thoſe with­
out
, unleſs the ſounding Body do imme­
diately
ſtrike againſt ſome part of the in­
cloſing
Body.
But not having now time
to
handle Controverſies, we ſhall onely
annex
, That after the foregoing Experi­
ment
, we took a Bell of about two Inches
in
Diameter at the bottom, which was
ſupported
in the midſt of the cavity of
the
Receiver by a bent ſtick, which by
reaſon
of its Spring preſſ'd with its two
ends
againſt the oppoſite parts of the in­
ſide
of the Veſſel: in which, when it was
cloſ
'd up, we obſerv'd that the Bell ſeem'd
to
ſound more dead then it did when juſt
before
it ſounded in the open Air.
And
yet
, when afterwards we had as formerly
emptyed
the Receiver, we could not diſ­
cern
any conſiderable change (for ſome
ſaid
they obſerv'd a ſmall one) in the loud­
neſs
of the ſound, whereby it ſeem'd that
though
the Air be the principal medium
of
ſound, yet either a more ſubtle mat­
ter
may be alſo a medium of it, or elſe an
ambient
Body that contains but very
few
particles of Air, in compariſon of
thoſe
it is eaſily capable of, is ſufficient
for
that purpoſe.
And this, among o-
1ther things, invited us to conſider, whether
in
the above-mention'd Experiment made
with
the Bell and the Load-ſtone, there
might
not in the deſerted part of the Tube
remain
Air enough to produce a ſound:
ſince
the Tubes for the Experiment De
Vacuo
(not to mention the uſual thin­
neſs
of the Glaſs) being ſeldom made
greater
then is requiſite, a little Air might
bear
a not inconſiderable proportion to
the
deſerted ſpace.
And that alſo, in the
Experiment
De Vacuo, as it is wont to be
made
, there is generally ſome little Air
that
gets in from without, or at leaſt ſtore
of
bubbles that ariſe from the Body of
the
Quick-ſilver, or other Liquor it ſelf,
Obſervations
heedfully made have fre­
quently
informed us: And it may alſo
appear
, by what has been formerly deli­
vered
concerning the Torricellian Experi­
ment
.
Experi­
ment
27.
On the occaſion of this Experiment
concerning
ſounds, we may adde in this
place
, That when we try'd the Experiment
formerly
mention'd, of firing Gun-pow­
der
with a Piſtol in our evacuated Recei­
ver
, the noiſe made by the ſtriking of the
Flint
againſt the Steel, was exceeding
languid
in compariſon of what it would
1have been in the open Air. And on di­
vers
other occaſions it appear'd that the
ſounds
created within our exhauſted
Glaſs
, if they were not loſt before they
reach
'd the Ear, ſeem'd at leaſt to arrive
there
very much weaken'd.
We intended
to
try whether or no the Wire-ſtring of an
Inſtrument
ſhut up into our Receiver,
would
, when the ambient Air was ſuck'd
out
, at all tremble, if in another Inſtrument
held
cloſe to it, but without the Receiver
a
ſtring tun'd (as Muſicians ſpeak, how
properly
I now examine not) to an Uniſon
with
it, were briskly toucht, and ſet a Vi­
brating
.
This, I ſay, we purpoſ'd to try
to
ſee how the motion made in the Air
without
, would be propagated through the
cavity
of our evacuated Receiver.
But
when
the Inſtrument wherewith the tryal
was
to be made came to be imploy'd, it
prov
'd too big to go into the Pneumatical
Veſſel
, and we have not now the conveni­
ency
to have a fitter made.
We thought likewiſe to convey into
the
Receiver a long and ſlender pair of
Bellows
, made after the faſhion of thoſe
uſually
employ'd to blow Organs, and fur­
niſh
'd with a ſmall Muſical inſtead of an
1ordinary Pipe. For we hop'd, that by
means
of a ſtring faſtned to the upper
part
of the Bellows, and to the moveable
ſtopple
that makes a part of the Cover
of
our Receiver, we ſhould, by frequent­
ly
turning round that ſtopple, and the an­
nexed
ſtring, after the manner already
often
recited, be able to lift up and diſtend
the
Bellows; and by the help of a com­
petent
weight faſten'd to the ſame upper
part
of the Bellows, we ſhould likewiſe
be
able, at pleaſure, to compreſs them:
and
by conſequence, try whether that
ſubtler
matter then Air (which, accord­
ing
to thoſe that deny a Vacuum, muſt be
ſuppoſ
'd to fill the exhauſted Receiver)
would
be able to produce a ſound in the
Muſical
Pipe; or in a Pipe like that of or­
dinary
Bellows, to beget a Wind capable
to
turn or ſet a moving ſome very light
matter
, either ſhap'd like the Sails of a
Wind-Mill
, or of ſome other conveni­
ent
form, and expoſ'd to its Orifice.
This
Experiment
, I ſay, we thought to make,
but
have not yet actually made it for want
of
an Artificer to make us ſuch a pair of
Bellows
as it requires.
We had thoughts alſo of trying whe­
ther
or no, as Sounds made by Bodies in
1our Receiver become much more languid
then
ordinary, by reaſon of the want of
Air
, ſo they would grow ſtronger, in caſe
there
were an unuſual quantity of Air
crouded
and ſhut up in the ſame Veſſel,
which
may be done (though not without
ſome
difficulty) by the help of the Pump,
provided
the Cover and Stopple be ſo
firmly
faſten'd (by binding and Cement,
or
otherwiſe) to the Glaſs; and to each
other
, that there be no danger of the
condenſ
'd Airs blowing of either of them
away
, or its breaking through the jun­
ctures
.
Theſe thoughts, My Lord, as I
was
ſaying, we entertain'd; but for want
of
leaſure, as, of as good Receivers as
ours
, to ſubſtitute in its place, in caſe we
ſhould
break it before we learn'd the skill
of
condencing the Air in it, we durſt not
put
them in practice: Yet, on this occa­
ſion
, give me leave to advertiſe Your
Lordſhip
once for all, That though for
the
reaſons newly intimated, we have,
Onely
in the ſeventeenth Experiment,
taken
notice, that by the help of our En­
gine
the Air may be condenſ'd as well as
rarified
; yet there are divers other of our
Experiments
, whoſe Phænomena it were
1worth while to try to vary, by means of
the
compreſſion of the Air.
WE taught, among divers other

things
, when we diſcourſ'd of our
firſt
Experiment, That the Air ſhut up in
our
Receiver, preſſeth as ſtrongly upon
the
Bodies ſhut up with it, as if they
were
expoſ'd to the preſſure of the whole
Atmoſphere
.
That this was not incon­
ſiderately
propounded, we hope Your
Lordſhip
has gather'd from divers of the
things
already recited: But yet perhaps it
will
not be amiſs to ſubjoyn, by way of
further
confirmation of the ſame truth, the
following
Experiment, which ſhould have
accompanied
the 20th, but the Paper where
in
the one was written chanc'd not to beat
hand
, when the other was ſent away.
Experi­
ment
28.
We convey'd into the Receiver a new
Glaſs
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 ſtopt it cloſe with a fit Cork.
The Pneumatical Veſſel being empty'd,
there
appear'd not any change in the in­
cloſ
'd Water, the Air impriſon'd with it,
not
having the force to blow out the ſtop-
1ple, which event, though it were no other
then
we expected, was differing from what
we
deſir'd.
For we would gladly have ſeen
what
change would have appear'd in the
Water
upon the Bottles being ſuddenly
unſtopp
'd, in a place where the ambient
Body
was ſo differing from our common
Air
.
Wherefore we did again put in the
Viol
, but leſs ſtrongly cloſ'd then for­
merly
, though as ſtrongly ſtopt as ſeem'd
requiſite
on ordinary occaſions: But when
the
Air was pump'd out of the Receiver,
that
within the Viol did quickly, as we
expected
, find or make it ſelf little paſſa­
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 Glaſs ap­
pear
'd all cover'd with them, and they,
upon
the regreſs of the excluded Air into
the
Receiver, did preſently flag and ſhrink
up
.
From theſe tryals it ſeem'd deducible
enough
, that whil'ſt the Viol continu'd
to
be well ſtopt, the included Water
did
, from the Air, ſhut up with it,
ſuſtain
a preſſure equal to that of the
Atmoſphere
; ſince till the Air could get
1out of the Glaſs, there appear'd no bub­
bles
in the Water, notwithſtanding the
want
of preſſure in the ambient Body.
But to be ſure to reach the chief end of
our
Experiment, we made uſe of this
ther
expedient: We cauſ'd a convenient
quantity
of Water to be put, and Her­
metically
ſhut up into a Glaſs Egge, to
whoſe
long Neck (which was purpoſely
made
of an unequal thickneſs) was fa­
ſten
'd to one end of a ſtring, whoſe
ther
end was ty'd to the Cover of our
Receiver
, after the manner elſewhere men­
tion
'd already: Then the Egge being
convey
'd into the Pneumatical Veſſel,
and
that being evacuated, we did, by
turning
the braſs Stopple formerly de­
ſcrib
'd amongſt the parts of our En­
gine
, ſo ſhorten the ſtring as to break the
Glaſs
; whereby liberty being given to
the
Air impriſon'd in the Egge, to paſs
into
the capacity of the Receiver, the ſud­
den
receſs of the Air made the bubbles in
a
trice appear ſo numerous, and aſcend
ſo
ſwiftly in the Water, that their motion
look
'd like that of a violent ſhower of
Rain
; ſave that the bubbles did not, like
the
drops of Rain, tend downwards, but
upwards
, which made me reſemble this
1Phænomenon to what I have ſeen happen
in
the diſſolution of Seed-Pearl in ſome
acid
Menſtruum, in which, if a good quan­
tity
of the little Pearls be caſt whole, they
will
at firſt, if the Menſtruum be ſharp
nough
, be carryed in ſwarms from the
bottom
to the top of the Liquor.
We
will
adde, that without ſealing up the
Glaſs
, this Experiment may be try'd in
one
of our ſmalleſt Receivers, for there
the
exſuction of the ambient Air may be
perform
'd ſo nimbly, that immediately
the
bubbles lurking in the Water are al­
low
'd to diſplay themſelves, and aſcend
in
throngs; inſomuch, as having in ſuch
a
Receiver try'd the Experiment with
Wine
(as a more ſpirituous Liquor) in­
ſtead
of Water, the Red-Wine appear'd
all
cover'd, with a copious, but vaniſhing
white
Froth, almoſt as if a Veſſel full of
bottl
'd drink had been unwarily open'd.
IT may not a little conduce to the clear­

er
explication of divers Points in the
Doctrine
of Meteors, and perhaps of
ſome
other Phyſiological difficulties, to
diſcover
what the Air does to the motion
of
thoſe Steams or Exhalations that aſ-
1cend into it, namely, Whether they mount
upwards
by vertue of any ſuch poſitive le­
vity
(as ſome Peripateticks ſpeak) ac­
quir
'd together with their Aërial nature,
as
inables them to pierce through part of
the
Atmoſphere, and over-come its re­
ſiſtance
.
Or elſe, whether theſe ſteams
being
once raiſ'd above the Earth by their
agitation
, have their aſcent and ſuſtenta­
tion
aloft, rather promoted then hindred
by
the Air: as the inferior parts of that,
being
thicker and heavier then the ſupe­
rior
, the ſteams can more eaſily continue
for
a while their agitation upwards then
downwards
; And afterwards are by the
ſame
fluidity and thickneſs of the Air,
carried
to and fro in it, and kept from re­
lapſing
to the Earth, as in the Sea water
the
ſaline parts are kept from ſubſiding by
thoſe
aqueous ones wherewith they are
aſſociated
.
Experi­
ment
29
We hop'd to illuſtrate this matter, by
obſerving
the motion of the ſmoke, pro­
ceeding
from kindled or flaming Bodies in
our
exhauſted Receiver.
But as we for­
merly
noted, upon the exſuction of the
Air
, the ſmoking of thoſe Bodies pre­
ſently
ceaſ'd.
We had thoughts alſo of
conveying
into our Pneumatical Glaſs a
1hot Iron, with ſome Body eaſie to be
diſſipated
into ſmoke ſet upon it, but con­
ſider
'd, that neither was that way free
from
inconveniencies; eſpecially this, that
the
hot Body would make the Impriſon'd
Air
circulate within the Receiver, and
conſequently
make it queſtionable whe­
ther
the aſcent of the ſteams would not
be
due to the new and acquired motion of
the
Air.
Wherefore I bethought my ſelf of an­
other
way to ſatisfie in ſome meaſure my
curioſity
, to wit, by means of a certain
Liquor
, which I call'd to minde that ſome
years
ago I had (for a deſign that belongs
not
to our preſent purpoſe) prepar'd;
which
, I ſuppoſe, I ſhew'd Your Lord­
ſhip
, and which had the luck to be ta­
ken
notice of by divers very Ingenious
and
Famous Men.
For this Liquor,
though
moſt of its Ingredients be Metals,
and
all of them ponderous enough, is yet
of
that nature, that whilſt the Viol where­
in
it is kept is ſtopt (how ſlight a Cover
ſoever
) both the Liquor and the Glaſs
are
tranſparent; and ſo is that upper half
of
the Glaſs to which the Liquor reaches
not
.
But aſſoon as ever the ſtopple is ta­
ken
out, and full acceſs is given to the ex-
1ternal Air, both the inward part of the
Cork
, and the Liquor it ſelf, do preſent­
ly
ſend upwards, and ſcatter abroad a
fume
as thick and white, as if there were
a
quantity of Alablaſter-duſt thrown up
into
the Air: And this ſmoking of the
Liquor
laſts till my unwillingneſs to waſte
it
, invites me ſtop it again; and then the
aſcenſion
of the fumes ſuddenly ceaſes, till
the
Viol be again unſtop'd.
This fuming Liquor then I thought
would
much conduce to the diſcovery I
deſir
'd to make, ſince it ſav'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 ſtopple one end of a ſtring, of
which
the other end was made faſt to the
Cover
of the Pneumatical Glaſs, the Li­
quor
was carefully cloſ'd up after the
wonted
manner; then the Air being dili­
gently
pump'd out, the Viol was unſtopt
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 ſome white fumes, which
1ſeem'd to proceed from the Air before
impriſon
'd in the Viol, and diffuſing it
ſelf
ſuddenly into the capicity of the
Receiver
.
Yet we afterward obſerv'd,
as
we expected, That the fumes did not
mount
and diſperſe themſelves as they
uſe
to do in the open Air, but that, when
by
reaſon of the agitation of the Cor­
puſcles
of the Liquor, which could not
continue
their motion in ſo narrow a
ſpace
as the Viol afforded them, and were
therefore
reduc'd to thruſt one another
out
of it; when, I ſay, by theſe aſſi­
ſtances
the fumes were aſcended to the lip
of
the Viol, they mounted no higher,
but
ran down along the out-ſide of the
Viol
to the bottom of it; and thence
along
, a long and inclining piece of Lead,
on
which the Viol reſted, like a little
Stream
(not very much bigger then a
Swans
Quill) whoſe nature it ſeemd to
mulate
ſo well, that it quitted not the Viol
till
it was come to the bottom of it, and
then
forſook it in ſuch a manner as a
ſtream
of Water of the ſame bigneſs
would
have done.
And this ſtream laſted
a
pretty while, and would probably have
laſted
longer, but that being loath to waſte
my
Liquor, I let in at the Stop-cock a
1pretty deal of the external Air; notwith­
ſtanding
which, finding after a while the
ſtream
did run afreſh; though, as it ſeem'd,
not
altogether ſo copious as before: I let
as
much more Air, as would, come in, and
found
(ſomewhat to my wonder) that
though
the ſtream formerly mention'd
diſ-appear
'd, yet there appear'd not any
white
fumes to ariſe, either from the Cork,
or
out of the Viol it ſelf, no not when
the
Cover was remov'd from the Recei­
ver
; though not onely after a while there
aſcended
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 preſently
after
unſtop'd it in an open Window, we
found
both it and the Cork immediatly
to
ſend forth a yet much more plentiful
ſmoak
.
Though it be now divers years
ſince
this Numerical Liquor was prepa­
red
, after the manner mention'd either
by
Carneiades or Eleutherius (for I do not
well
remember which) in thoſe Dialogues
concerning
Heat and Flame that have
bove
been mention'd.
More Circumſtances concerning theſe
Fumes
we might have obſerv'd, had we
not
been deterr'd by an Indiſpoſition in
1point of health, from having much to do
with
ſteams of ſo dangerous a nature, as by
that
of the Ingredients of this Liquor
theſe
ſeem likely to be of.
The Reflections that may be made up­
on
this Experiment, we have not now the
leaſure
to proſecute, and therefore ſhall
content
our ſelves to recommend the ſe­
veral
Circumſtances of it to Your Lord­
ſhips
ſerious conſideration; and to take
notice
(en paſſant) that ſteams in an am­
bient
Body, or a medium thinner then
themſelves
, may both tend downwards,
and
otherwiſe emulate the nature of a
Liquor
; which I therefore point at, that
it
may appear the leſs ſtrange, if we ſome­
times
ſpeak of the Atmoſphere as of a
kinde
of Liquor, in compariſon of that
more
thin and ſubtle Celeſtial Matter that
ſurrounds
it.
And though it might perchance ſuf­
fice
to have on this occaſion intima­
ted
thus much; yet, leſt this way
of
ſpeaking of the Atmoſphere ſhould
be
thought too bold and extra­
vagant
, I am content to borrow an
Experiment
of the Diſcourſe former-
1ly mention'd (touching fluidity and firm­
neſs
) and ſubjoyn it here with alterations
ſuitable
to the contrivance of our Engine;
and
this the rather, becauſe I hope it may
conduce
to the diſcovery of the nature of
the
Atmoſphere: for which reaſon it
might
have been annext to what has been
noted
either upon the firſt, or eighteenth
Experiment
, but that when they were
written
and ſent away, it came not into
my
minde.
The Experiment then as we
try
'd in our Engine, was as follows.
WE took one of the ſmall Receivers,

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 ſmoak, we took it out
and
haſtily cloſ'd again the Receiver, that
the
ſmoak might not get away.
Then
ſtaying
awhile to let theſe fumes leiſurely
ſubſide
, we found, as we expected, that
after
ſome time they ſetled themſelves in
the
lower half of the Receiver, in a dark­
iſh
Body, leaving the upper half of the
Receiver
tranſparent, and as to ſight, full
of
nought but clear Air.
Now to mani­
feſt
that this ſmoak thus ſetled emulated
1a Liquor, we inclin'd the Engine that con­
tain
'd it, ſometimes to one ſide, and ſome­
times
to the other; and obſerv'd the
ſmoak
to keep its ſurface almoſt Hori­
zontal
, notwithſtanding the ſtooping of
the
Veſſel that held it, as Water or an­
other
Liquor would in the like caſe have
done
.
And if by a quicker rocking of the
Engine
the ſmoke were more ſwiftly ſha­
ken
, it would, like Water, either Vibrate
to
and fro from one ſide to the other of
the
Glaſs, or elſe have its ſurface manifeſt­
ly
curll'd with Waves, but preſerve its
ſelf
in an intire and diſtinct Body from the
incumbent
Air; and being permitted to
reſt
awhile, would ſoon recover its for­
mer
ſmooth and level ſuperficies: If alſo
the
Key were turn'd and the Valve un­
ſtopp
'd, ſo that there was a free, though
but
a narrow paſſage open'd betwixt the
external
Air and the cavity of the Recei­
ver
, then would ſome of this ſmoak fall
down
, as it were, in a ſtream into the ſub­
jacent
Cylinder, and a proportionate
quantity
of the outward Air, would ma­
nifeſtly
aſcend through it into the incum­
bent
Air, much after the ſame manner as
if
you invert a Viol with a long Neck, and
well
fill'd with Red-Wine, into a Glaſs
1full of fair water, you ſhall ſee the Water
and
Wine by degrees mingle with one an­
other
; the one falling downe as it were in
little
colour'd ſtreames, and the other aſ­
cending
into its room in the like curled
ſtreames
, ſometimes preceded by round
parcels
of water, which, by reaſon of their
tranſparency
, looke almoſt like bubbles.
The other circumſtances of this Experi­
ment
, belonging not all of them to our
preſent
purpoſe, we ſhall content our
ſelves
with taking notice of one which
ſeemes
the moſt important, and may illu­
ſtrate
and confirme ſome things former­
ly
delivered.
And it was, That if, when
the
ſuperficies of our Smoke lay ſmooth
and
horizontal, a hot iron were held near
the
our ſide of the Receiver, the Neigh­
bouring
part of the included fumes (for
the
reſt did not very much alter their for­
mer
ſuperficies) being rarified by the heat,
would
readily aſcend in a large Pillar of
ſmoke
to the very top of the Receiver,
yet
without ſeeming to looſe a diſtinct
ſuperficies, or to be confounded with Air;
below
which, upon the receſs of the ad­
ventitious
heat that by agitating it im­
pell
'd it upward, it would againe ſub­
ſide
.
1
Experi­
ment
30.
All which being added to the late Ex­
periment
of the ſmoking Liquor, and
to
what may be from that which has been
elſewhere
ſayd, gather'd to the ſame pur­
poſe
, will, I hope, keep it at leaſt from ap­
pearing
abſur'd: If ſince we ſee that there
is
ſo great an inequality in the denſity and
weight
of Liquors, that water is neere 14
times
thinner or lighter than Quick-ſilver
of
the ſame bulk, and well dephlegm'd;
Spirit
of Wine yet much lighter than wa­
ter
; we venter to ſpeak ſometimes of the
Atmoſphere
, as if it were a peculiar kind
of
thin and halituous Liquor (if I may ſo
call
it) much lighter than Spirit of Wine.
To theſe things I know not whether it
will
be requiſite to add, that as we late­
ly
took notice of conſpicuous waves that
appear
'd upon the ſuperficies of our agi­
tated
ſmoke.
So ſome ſuch thing may
not
abſurdly be conjectur'd to happen
on
the ſuperficies of the Atmoſphere,
by
thoſe ſtrange ruggedneſſes that ap­
peare
(eſpecially in the Spring and Fall,
when
exhalations and vapours are wont to
aſcend
moſt plentifully) upon the Limb
or
Edge of the Riſing and Setting Sun.
I
ſpeake
thus diffidently upon this occaſion
becauſe
I know that by the Fluctuation or
1Boyling of the Sun's own ſuperficies di­
verſe
eminent Mathematicians have plau­
ſibly
enough (but how truly I leave
your
Lordſhip to Judge) endeavour'd to
give
an Account of it.
But if we will joine
with
thoſe that have aſcrib'd of late this
Phænomenon 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
ſurface Atmoſphere is oftentimes (if
not
alwayes) exceedingly curl'd or wav'd.
And certainly it is ſomewhat wonderfull
as
well as very pleaſant to behold, how,
to
him that looks upon the ſetting Sun
through
a long & excellent Teleſcope,
there
will not only appeare ſtrange ine­
qualities
in the edge of it (inſomuch that
I
have often ſeen it more indented than a
Saw
) but thoſe inequalities will vaniſh in
one
place and preſently appeare in ano­
ther
, and ſeem perfectly to move like
waves
ſucceeding and deſtroying one an­
other
; ſave that their Motion oftentimes
ſeemes
to be quickeſt as if in that vaſt ſea
they
were carried on by a current, or at
leaſt
by a tide.
And this (as we elſe
where
note) appear's to the eye not on­
ly
when it looks directly through the te-
1leſcope upon the ſunne; but alſo when a
large
and well defin'd image of the ſunne
is
by the ſame teleſcope brought into a
roome
and caſt upon a ſheet of white pa­
per
.
But to inſiſt on this were to digreſs:
and
therefore I will proceed to experi­
ments
of another kind.
IT has been admir'd by very ingenious

Men
, that if the exquiſitly poliſh'd
ſurfaces
of two flat peeces of marble be ſo
congruous
to each other that from their
mutuall
application there will reſult an
immediate
contact, they will ſtick ſo faſt
together
, that he that lifts up the upper­
moſt
, ſhall, if the undermoſt be not ex­
ceeding
heavy, lift up that too, and ſuſ­
taine
it aloft in the free aire.
A proba­
ble
cauſe of this ſo cloſe adheſion we have
elſewhere
endeavour'd to deduce from the
unequall
preſſure of the Air upon the un­
dermoſt
ſtone; For the lower ſuperficies
of
that ſtone being freely expos'd to the
Air
is preſſ'd upon by it, whereas the up­
permoſt
ſurface, being contiguous to the
ſuperiour
ſtone, is thereby defended from
the
preſſure of the Air which conſequent­
ly
preſſing the lower ſtone againſt the up-
1per, hinders it from falling, as we have
elſewhere
more fully declar'd.
Upon
theſe
grounds we conjectur'd that in caſe
we
could procure two marbles exactly
ground
to one another; and in caſe we
could
alſo ſufficiently evacuate our Re­
ceiver
, the lower ſtone would, for want
of
the wonted and ſuſtaining preſſure of
the
Air, fall from the upper.
But the
further
tryal of this Experiment we muſt,
unleſs
your Lordſhip think it worth Your
making
at Paris, put off till a fitter
opportunity
.
For where we now are, we
cannot
procure marbles ſo exactly ground,
that
they will ſuſtaine one another in the
Air
, above a minute or two, which is a
much
ſhorter time than the emptying of
our
Receiver requires.
We did indeed
try
to make our marbles ſtick cloſe to­
gether
by moiſtening their polliſhed ſur­
faces
with rectifi'd ſpirit of Wine, in re­
gard
that Liquor by its ſudden avolation
from
marble, if powr'd thereon, without
leaving
it moiſt or leſs ſmooth, ſeem'd
unable
to ſuſtaine them together after the
manner
of a glutinous body, and yet
ſeem
'd ſufficient to exclude and keep out
the
Air.
But this we try'd to little pur­
poſe
, for having convey'd into the Recei-
1ver two black ſquare marbles (the one of
two
inches and a third in length or
breadth
, and ſomewhat more than halfe
an
inch in thickneſs: The other of the ſame
extent
, but not much above halfe ſo
thick
) faſten'd together by the interven­
tion
of pure Spirit of Wine; and having
ſuſpended
the thicker by a ſtring from the
cover
, we found not that the exſuction of
the
ambient Air would ſeparate them,
though
a weight amounting to four oun­
ces
were faſten'd to the lowermoſt mar­
ble
to facilitate it's falling off.
Experi­
ment
31,
I would gladly have the Experiment
try
'd with marble ſo well polliſh't as to
need
no Liquor whatſoever to make them
cohere
, and in a Veſſel 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 ſtrong
coheſion
of theſe ſtones, otherwiſe than
by
keeping ev'n the ſubtl'ſt parts of the
Air
from getting in between them, yet it
ſeemed
that the not falling downe of the
lowermoſt
marble might without impro­
bability
be aſcrib'd to the preſſure of the
Air
remaining in the Receiver; which as
we
formerly noted having been able
1to keep a Cylinder of water of above
a
Foot in height from falling to the bot­
tom
of the Tube, may well enough be
ſuppoſ
'd capable of keeping ſo broad a flat
Marble
from deſcending.
And though this
may
ſeem a ſtrange proof of the ſtrength of
the
ſpring of Air, ev'n when rarified, yet it
will
ſcarce ſeem incredible to him that has
obſerv
'd how exceeding ſtrong a coheſion
may
be made betwixt broad Bodies, one­
ly
by their immediate touching one ano­
ther
.
A notable inſtance of which, I
have
met with in this ſhort Narrative of

the
Learned Zucchius. Fuveni (ſays he)
lacertorum ſuorum robur: jactanti propo­
ſita
ſemel eſt lamina ærea, per anſam in
medio
extantem apprehenſam elevanda è
tabula
marmorea, cui optime congruebat:
qui
primo tanquam rem ludicr am puero
committendam
contempſit: tum inſtanti­
bus
amicis manum utrámque admovens,
cum
luctatus diu hærentem non removiſſet,
excuſavit
impotentiam, objecta perigrini
& potentiſsimi glutinis interpoſitione, quo
fortiſsime
copulante nequiret divelli; do­
nec
vidit ab alio per tabulam facilimè lami­
nam
deduci, & ad extrema product am, &
actam
in tranſverſum inàe deportari.
But
that
we may learn from our own Engine,
1that two Bodies, though they touch each
other
but in a ſmall part of their ſurfaces,
may
be made to cohere very ſtrongly,
onely
by this, That the Air preſſes much
more
forcibly upon the inferior ſuperfi­
cies
of the lowermoſt Body, then upon
the
upper ſurface of the ſame: We will
hereunto
annex the following Experi­
ment
, though out of the order wherein
they
were made.
P. Nic.
Zucchius
opal
Schot:
part
1.
Experi­
ment
32.
I remember I have, in a Diſcourſe con­
cerning
Fluidity and Firmneſs, made
mention
of my having, by the exſuction
of
the Air out of a Glaſs Veſſel, made
that
Veſſel take up, or ſuck up (to ſpeak in
the
common Language) a Body weighing
divers
Ounces; but our Engine affording
us
the opportunity of making conſider­
abler
Experiments of that kinde, We
thought
fit to make a further tryal of the
force
of the Atmoſphere's preſſure up­
wards
, after the following manner.
The Receiver having been exquiſitely
cloſ
'd, as we have often taught already,
and
the Air being in a good meaſure drawn
out
of it, it was remov'd from off the
Pump
: and to the lower Branch of the
1Stop-cock, there was ſpeedily apply'd a
tapering
Valve of braſs, ſuch as is deſcrib'd
in
the 9th 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 ſurface of
the
ſtopple and the internall edge of the
branch
, thoſe intervals were ſtop't with
a
little Diachylon.
And to the doore,
or
, (if you pleaſe) 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
braſs
belonging to the Valve faſten'd a
broad
ſcale 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 ſtreame upon the Valve
to
get in there, it did ſuddenly both ſhut
the
Valve and keep it ſhut ſo ſtrongly,
that
we had time to caſt in diverſe weights
one
after another into the Scale; till at
length
the weight overpowering the preſ­
ſure
of the Atmoſphere, drew downe the
Valve
by the ſtringes that ty'd the Scale
to
it, and gave liberty to the outward Air
to
ruſh into the Receiver.
Though a-
1nother 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 ſuddenly 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 exhauſted, and though it leak'd
whil
'ſt the reſt of the Experiment was in
proſecution
, and though the Valve
whereon
the Cylinder of the Atmoſphere
could
preſs, were not above an Inch and
a
half in Diameter, yet the weight kept
up
by ſuction, or rather ſupported by the
Air
, namely the Valve, the Seal and
what
was caſt into it, being ſent to be
weigh
'd, amounted to about ten of our
common
Pounds, conſiſting of ſixteen
Ounces
apiece: So that we doubted not
but
that, had the Experiment been made
with
favorable Circumſtances, the Air
endeavoring
to preſs in at the Orifice of
the
Stop-cock, would have kept a very
much
greater weight from falling out of
it
; I ſay the Air, becauſe we found, by
tryal
purpoſely made, that neither the
imperfect
contact of the Valve and the
Stop-cock
, nor the Diachylon that was
1employ'd to fill up the little Crannies left
betwixt
them, were conſiderable in this
Experiment
; by which may among other
things
appear, that I did not without
cauſe
in the above-nam'd Diſcourſe touch­
ing
Fluidity and Firmneſs, aſcribe a great
force
, ev'n to ſuch Pillars of Air as may
be
ſuppoſ'd to begin at the top of the
Atmoſphere
, and recoyling from the
ground
to terminate on the Bodies on
which
they preſs: ſince in the preſent Ex­
periment
ſuch a weight was ſupported by
ſo
ſlender a Cylinder of Air, rebounding
from
the Earth to the Valve whereon it
did
bear.
BUt in regard we have not yet been

able
to empty ſo great a Veſſel as our
Receiver
, ſo well as we can the Cylinder
it
ſelf; our Pump alone may afford us a
nobler
inſtance of the fotce of the Air we
live
in, inſomuch, that by help of this
part
of our Engine, we may give a pretty
near
gheſs at the ſtrength of the Atmo­
ſphere
, computed as a weight.
And the
way
may be this; Firſt, the Sucker be­
ing
brought to move eaſily up and down
the
Cylinder, is to be impell'd to the top
1of it: Then the Receiver muſt be taken
off
from the Pump, that the upper Ori­
fice
of the Cylinder remaining open, the
Air
may freely ſucceed the Sucker, and
therefore
readily yield to its motion
downward
.
This done, there muſt be
faſten
'd to one of the Iron Teeth of the
Sucker
, ſuch a weight as may juſt ſuffice
to
draw it to the bottom of the Cylinder.
And having thus examin'd what weight is
neceſſary
to draw down the Sucker, when
the
Atmoſphere makes no other then the
ordinary
reſiſtance of the Air againſt its
deſcent
; the Sucker muſt be again forc'd
to
the top of the Cylinder, whoſe upper
Orifice
muſt now be exactly cloſed; and
then
(the firſt weight remaining) we eaſi­
ly
may, by hanging a Scale to the above­
mention
'd Iron (that makes part of the
Sucker
) caſt in known weights ſo long,
till
in ſpight of the reluctancy of the At­
moſphere
the Sucker be drawn down.
For
to
theſe weights in the Scale, that of the
Scale
it ſelf being added, the ſum 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 Atmoſphere.
Experi­
ment
33.
According to this method we did, ſince
1the writing of the laſt Experiment, at­
tempt
to meaſure the preſſure of the At­
moſphere
, but found it more difficult then
we
expected, to perform it with any ac­
curateneſs
; for though by the help of the
Manubrium the Sucker moved up and
down
with ſo much eaſe, that one would
have
thought that both its convex ſurface,
and
the concave one of the Cylinder were
exquiſitely
ſmooth, & as it were ſlippery;
yet
when the Sucker came to be moved
onely
with a dead weight or preſſure (that
was
not (like the force of him that
pump
'd) intended as occaſion required)
we
found that the little rufneſſes, or other
inequalities
, and perhaps too, the unequal
preſſure
of the Leather againſt the cavity
of
the Cylinder, were able now and then
to
put a ſtop to the deſcent or aſcent of
the
Sucker, though a very little external
help
would eaſily ſurmount that impedi­
ment
; and then the Sucker would, for a
while
, continue its formerly interrupted
motion
, though that aſſiſtance were with­
drawn
.
But this diſcouragement did not
deterre
us from proſecuting our Experi­
ment
, and endeavoring, by a careful trial,
to
make it as inſtructive as we could.
We found then that a Leaden Weight,
1of 28 pounds (each conſiſting of ſixteen
Ounces
) being faſtned to one of the teeth
of
the Sucker, drew it down ſlowly
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 Manubrium, its motion in the
Cylinder
had been before purpoſely faci­
litated
.
This done, the upper Orifice of
the
Cylinder was very carefully and cloſe­
ly
ſtopp'd, the Valve being likewiſe ſhut
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
leiſurely, we took off the twenty
eight
pound weight; and being unable to
procure
juſt ſuch weights as we would
have
had, we hung on, inſtead of it, one
of
fourteen pound, but found that, with
the
reſt, unable to carry down the Sucker.
And to ſatisfie our ſelves, and the Spe­
ctators
, that it was the reſiſtance of the
ambient
Air that hinder'd the deſcent of
ſo
great a weight, after that we had try'd
that
upon unſtopping the Valve, and
1thereby opening an acceſs to the external
Air
, the Sucker would be immediately
drawn
down: After this, I ſay, we made
this
further Experiment, That having by
a
Man's ſtrength forcibly depreſſ'd the
Sucker
to the bottom of the Cylinder,
and
then faſtned weights to the above­
named
Iron that makes part of that Suc­
ker
, the preſſure of the external Air find­
ing
little or nothing in the cavity of the
evacuated
Cylinder to reſiſt it, did pre­
ſently
begin to impell the Sucker, with
the
weights that clogg'd it, towards the
upper
part of the Cylinder, till ſome
ſuch
accidental Impediment as we former­
ly
mention'd, check'd its courſe; and
when
that rub, which eaſily might be, was
taken
out of the way, it would continue
its
aſcent to the top, to the no ſmall won­
der
of thoſe By ſtanders, that could not
comprehend
how ſuch a weight could aſ­
cend
, as it were, of it ſelf; that is, with­
out
any viſible force, or ſo much as Su­
ction
to lift it up.
And indeed it is very
conſiderable
, that though poſſibly there
might
remain ſome particles of Air in the
Cylinder
, after the drawing down of the
Sucker
; yet the preſſure of a Cylinder of
the
Atmoſphere, ſomewhat leſs then
1three Inches in Diameter (for, as it was
ſaid
in the deſcription of our Engine, the
cavity
of the Cylinder was no broader)
was
able, uncompreſſ'd, not only to ſuſtain,
but
even to drive up a weight of an hun­
dred
and odde pounds: for beſides the
weight
of the whole Sucker it ſelf, which
amounts
to ſome pounds, the weights an­
nexed
to it made up a hundred and three
pounds
, beſides an Iron Bar, that by con­
jecture
weighed two pounds more; and
yet
all theſe together fall ſomewhat ſhort
of
the weight which we lately mention'd,
the
reſiſtance of the Air to have held ſu­
ſpended
in the cavity of the Cylinder.
And though (as hath been already ac­
knowledg
'd) we cannot, peradventure,
obtain
by the recited means ſo exact an
account
as were to be wiſh'd, of what we
would
diſcover: Yet, if it ſerve us to
ground
Conjectures more approaching to
the
Truth, then we have hitherto met
with
, I hope it will be conſider'd (which
a
famous Poet judiciouſly ſays)
Eſt quoddam prodire tenus, ſi non da­
tur
ultra.
Peradventure it will not be imperti-
1nent to annex to the other Circumſtances
that
have been already ſee down concern­
ing
this Experiment, That it was made in
Winter
, in Weather neither Froſty nor
Rainy
, about the change of the Moon,
and
at a place whoſe latitude is near about
51
d and a half: For perhaps the force or
preſſure
of the Air may vary, according
to
the Seaſons of the Year, the tempera­
ture
of the Weather, the elevation of the
Pole
, or the phaſes of the Moon; all, or
even
any of them ſeeming capable to al­
ter
either the heighth or conſiſtence of the
incumbent
Atmoſphere: And therefore
it
would not be amiſs if this Experiment
were
carefully tryd at ſeveral times and
places
, with variety of Circumſtances.
It
might
alſo be try'd with Cylinders of ſe­
veral
Diameters, exquiſitely fitted with
Suckers
, that we might know what pro­
portion
ſeveral Pillars of the Atmoſphere
bear
, to the Weights they are able to ſu­
ſtain
or lift up; and conſequently, whe­
ther
the increaſe or decrement of the re­
ſiſtance
of the ambient Air, can be re­
duc
'd to any regular proportion to the
Diameters
of the Suckers: Theſe, and
divers
other ſuch things which may be
try
'd with this Cylinder, might moſt of
1them bemore exactly try'd by the Tori­
cellian
Experiment, if we could get Tubes
ſo
accurately blown and drawn, that the
Cavity
were perfectly Cylindrical.
To dwell upon all the ſeveral Refle­
ctions
, that a ſpeculative Wit might
make
upon this and the foregoing Expe­
riment
: (I mean the thirty third and thir­
ty
ſecond, would require almoſt a Vo­
lume
, whereas our occaſions will ſcarce
allow
us time to touch upon three or
four
of the chief Inferences that ſeem de­
ducible
from them, and therefore we ſhall
content
our ſelves to point at thoſe
few
.
And firſt, as many other Phænomena
of
our Engine, ſo eſpecially, the two
lately
mention'd Experiments, ſeem ve­
ry
much to call in queſtion the receiv'd
Opinion
of the Nature or Cauſe of Su­
ction
.
For 'tis true indeed, that when men
ſuck
, they commonly uſe ſome manifeſt
endeavour
by a peculiar motion of their
Mouthes
, Cheſts, and ſome other conſpi­
ring
parts, to convey to them the body
to
be ſuckt in.
And hence perhaps they
have
taken occaſion, to think that in all
1Suction there muſt be ſome Endeavour
or
motion in the ſucking to attract the
ſucked
Body.
But in our laſt Experi­
ment
it appeares not at all how the up­
per
part of the empty'd Cylinder that re­
maines
moveleſs all the while, or any
part
of it, does at all endeavour to draw
to
it the depreſſed Sucker and the an­
nex
'd weights.
And yet thoſe that be­
hold
the aſcention of the Sucker, without
ſeriouſly
conſidering the cauſe of it, doe
readily
conclude it to be rayſ'd by ſome­
thing
that powerfully Sucks or attracts
it
, though they ſee not what that may
be
or where it lurks.
So that it ſeemes
not
abſolutely neceſſary to Suction, that
there
be in the Body, which is ſaid to ſuck,
an
endeavor or motion in order thereun­
to
, but rather that Suction may be at leaſt
for
the moſt part reduc'd to Pulſion, and
its
effects aſcrib'd to ſuch a preſſure of
the
neighboring air upon thoſe Bodies
(whther aërial, or of other Natures) that
are
contiguous to the Body that is ſayd to
attract
them, as is ſtronger than that Sub­
ſtance
which poſſeſſes the cavity of that
ſucking
Body is able to reſiſt.
To ob­
ject
here, that it was ſome particles of
Air
remaining in the empty'd Cylin-
1der that attracted this weight to obviate
a
Vacuum, will ſcarce be ſatisfactory; un­
leſs
it can be cleerly made out by what li­
tle
hooks, or other grappling Inſtruments,
the
internal Air could take hold of the
Sucker
; how ſo litle of it obtain'd the
force
to lift up ſo great a weight; and why
alſo
, upon the letting in of a litle more
Air
into one of our evacuated Veſ­
ſels
, the attraction is, inſtead of being
ſtrengthen
'd, much weaken'd, though,
if
there were danger of a Vacuum be­
fore
, it would remain, notwithſtanding
this
ingreſs of a little Air.
For that ſtill
there
remain'd in the capacity of the ex­
hauſted
Cylinder ſtore of little rooms,
or
ſpaces empty or devoid of Air, may
appear
by the great violence wherewith
the
air ruſhes in, if any way be open'd to it.
And that 'tis not ſo much the decrement
of
the Vacuum within the cavity of the
veſſel
that debilitates the attraction, as the
ſpring
of the included air (whoſe preſence
makes
the decrement) that does it by
reſiſting
the preſſure of the external Air,
ſeems
probable, partly from the Diſabi­
lity
of vacuities, whether greater or leſſer,
to
reſiſt the preſſure of the Air; and part­
ly
by ſome of the Phænomena of our Ex-
1periments, and particularly by this Cir­
cumſtance
of the three and Thirtieth,
that
the Sucker was by the preſſure 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
conſequently
left a great Vacuum in the
cavity
of it; but when the Sucker had
been
already impel'd almoſt to the top of
the
Cylinder, and conſequently, when the
Vacuum that remain'd was become very
litle
in compariſon of that which preceded
the
beginning of the Sucker's aſcention.
In the next place, theſe Experiments
may
teach us, what to judge of the vul­
gar
Axiom receiv'd for ſo many Ages
as
an undoubted Truth in the Peripate­
tick
Schools; That Nature abhorres
and
flys a Vacuum, and that to ſuch a de­
gree
, that no humane power (to go no
higher
) is able to make one in the Uni­
verſe
; wherein Heaven and Earth would
change
places, and all its other Bodyes
rather
act contrary to their own Nature,
than
ſuffer it.
For, if by a Vacuum we
will
underſtand a place perfectly devoid
of
all corporeal Subſtance, it may be in­
deed
then, as we formerly noted be plau­
ſibly
enough maintain'd, that there is
1no ſuch thing in the world; but that the
generality
of the Pleniſts, (eſpecially till
of
late yeares ſome of them grew more
wary
) did not take a Vacuum in ſo ſtrict
a
Senſe, may appear by the Experiments
formerly
, and ev'n to this Day imploy'd
by
the Deniers of a Vacuum, to prove it
impoſſible
that there can be any made.
For when they alleadge (for Inſtance)
that
when a man ſucks Water through a
long
Pipe, that heavy Liquor, contrary
to
its Nature, aſcends into the Sucker's
mouth
, only, to fill up that room made
by
the Dilatation of his Breſt and
Lungs
, which otherwiſe will in part be
empty
.
And when they tell us, that the
reaſon
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
uſe
a more familiar Example, when they
teach
, that the cauſe why in a Gardiner's
watering
Pot ſhap'd conically, or like a
Sugar-Loaf
fill'd with Water, no Liquor
fals
down through the numerous holes
at
the bottome, whilſt the Gardiner keeps
his
Thumb upon the Orifice of the litle
hole
at the top, and no longer, muſt be
that
it in the caſe propoſed the Water
1ſhould deſcend, the Air being unable to
ſucceed
it, there would be left at the up­
per
and deſerted part of the Veſſel a Va­
cuum
, that would be avoided if the hole
at
the top were open'd.
When (I ſay)
they
alleadge ſuch Experiments, the
Tendency
of them ſeems plainly to im­
port
, that they mean, by a Vacuum, any
ſpace
here below that is not fill'd with a
viſible
body, or at leaſt with Air; though
it
be not quite devoy'd of all Body what­
ſoever
.
For why ſhould Nature, out of
her
deteſtation of a Vacuum, make Bo­
dies
act contrary to their own Tendency,
that
a place may be fill'd with Air, if its
being
ſo were not neceſſary to the avoi­
ding
of a Vacuum.
Taking then a Vacuum in this vulgar
and
obvious ſence, the common opinion
about
it ſeems lyable to ſeveral Exce­
ptions
, whereof ſome of the chief are
ſuggeſted
to us by our Engine.
It will not eaſily then be intelligibly
made
out, how hatred or averſation,
which
is a paſſion of the Soule, can either
for
a Vacuum, or any other object, be ſup­
pos
'd to be in Water, or ſuch like inani­
mate
Body, which cannot be preſum'd
to
know when a Vacuum would enſue; if
1they did not beſtirre themſelves to pre­
vent
it, nor to be ſo generous as to act
contrary
to what is moſt conducive to
their
own particular preſervation for the
publique
good of the Univerſe.
As much
then
of intelligible and probable Truth,
as
is contain'd in this Metaphoricall Ex­
preſſion
, ſeems to amount but to this;
That
by the Wiſe Author of Nature
(who is juſtly ſayd to have made all
things
in number, weight, and meaſure,)
the
Univerſe, and the parts of it, are ſo
contriv
'd, that it is as hard to make a Va­
cuum
in it, as if they ſtudiouſly conſpir'd
to
prevent it.
And how far this it ſelfe
may
be granted, deſerves to be further
conſider
'd.
For in the next place, our Experiments
ſeem
to teach, that the ſuppoſed Averſa­
tion
of Nature to a Vacuum is but acci­
dental
, or in conſequence partly of the
Weight
and Fluidity, or, at leaſt, Fluxi­
lity
of the Bodies here below; and partly,
and
perhaps principally, of the Spring of
the
air, whoſe reſtleſs endeavor to expand
it
ſelfe every way, makes it either ruth
in
it ſelfe, or compel the interpos'd bo­
dys
into all ſpaces, where it finds no grea­
ter
reſiſtance than it can ſurmount.
And
1that in thoſe motions which are made ob­
fugamVacui
(as the common phraſe is) Bo­
dys
act without ſuch generoſity & Con­
ſideration
, as is wont to be aſcrib'd to
them
, is apparent enough in our 32d Ex­
periment
, where the torrent of Air, that
ſeem
'd to ſtrive to get into the Empty'd
Receiver
, did plainly prevent its own
Deſigne
, by ſo impelling the Value, as
to
make it ſhut the only Orifice the Air
was
to get in at.
And if afterwards ei­
ther
Nature, or the internal Air, had a de­
ſigne
the external Air ſhould be attra­
cted
, they ſeem'd to proſecute very un­
wiſely
by continuing to ſuck the Valve
ſo
ſtrongly, when they found that by
that
Sucction the Valve it ſelfe could not
be
drawn in: Whereas by forbearing to
ſuck
, the Valve would by it's own weight
have
fall'n down, and ſuffer'd the exclu­
ded
Air to returne freely, and to fill
again
the exhauſted Veſſel.
And this minds me to take notice of
another
deficiency, pointed at by our Ex­
periments
in the common Doctrine of
thoſe
Pleniſts we reaſon with; for many
of
thoſe unuſual motions in Bodies, that
are
ſayd to be made to eſcape a Vacuum,
ſeem
rather made to fill it.
For why,
1to inſtance in our newly mention'd Ex­
periment
, aſſoon as the Valve was de­
preſs
'd by the weight we hung at it,
ſhould
the Air ſo impetuouſly and copi­
ouſly
ruſh 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, thoſe
litle
ſpaces in the Receiver, which the
corpuſcles
of that Air afterwards fill'd,
may
be concluded to have remain'd em­
pty
.
So that the ſeeming violence,
imploy
'd by Nature on the occaſion of
the
evacuating of the Veſſel, ſeems to
have
come too late to hinder the making
of
Vacuities in the Receiver, and only
to
have, aſſoon as we permitted, fill'd
up
with Air thoſe that were already
made
.
And as for the Care of the Publique
Good
of the Univerſe aſcrib'd to dead
and
ſtupid Bodies, wee ſhall only de­
mand
, why in our 19th Experiment, upon
the
Exſuction of the ambient Air, the
Water
deſerted the upper half of the
Glaſs-Tube
; and did not aſcend to fill
it
up, till the external Air was let in upon
it
: whereas by its eaſy and ſudden regai­
ning
that upper part of the Tube, it
1appear'd both that there was there much
ſpace
devoid of Air, and that the Water
might
with ſmall or no reſiſtance have
aſcended
into it, if it could have done ſo
without
the impulſion of the readmitted
Air
; which, it ſeems, was neceſſary to
mind
the Water of its formerly neglected
Duty
to the Univerſe.
Nay, for ought appeares, ev'n when
the
excluded Air, aſſoon as 'twas per­
mitted
, ruſht violently into our exhau­
ſted
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 leſs to prevent va­
cuity
's.
For though when as much Air as
will
, is gotten into our Receiver our pre­
ſent
Opponents take it for granted that
it
is full of Air; yet if it be remembred
that
when we made our 17th Experiment
we
crouded in more Air to our Receiver
than
it uſually holds; and if we alſo con­
ſider
(which is much more) the Air of
the
ſame conſiſtence with that in our
Receiver
may in wind guns, as is known,
and
as we have try'd, be compreſſed at
leaſt
into halfe its wonted room (I ſay at
leaſt
, becauſe ſome affirme, that the Air
1may be thruſt into an 8th, or a yet ſmaller
part
of its ordinary extent) it ſeems ne­
ceſſary
to admit either a notion of conden­
ſation
& rarefaction that is not intelligi­
ble
, or that in the capacity of our Recei­
ver
when preſum'd to be full of Air, there
yet
remain'd as much of ſpace as was ta­
ken
up by all the aërial corpuſcles unpoſ­
ſeſſed
by the Air.
Which ſeemes plainly,
to
infer that the Air that ruſh'd into our
empty
'd veſſel did not doe it preciſely
to
fill up the Vacuities of it, ſince it left ſo
many
unfill'd, but rather was thruſt in by
the
preſſure of the contiguous Air; which
as
it could not, but be always ready to ex­
pand
it ſelfe, where it found leaſt reſi­
ſtance
, ſo was it unable to fill the Recei­
ver
any more, then until the Air within
was
reduc'd to the ſame meaſure of Com­
pactneſs
with that without.
We may alſo from our two already of­
ten
mention'd Experiments further de­
duce
, that, (ſince Natures hatred of a
Vacuum is but Metaphorical and Ac­
cidental
, being but a conſequence or re­
ſult
of the preſſure of the Air and of the
Gravity
, and partly alſo of the Fluxility
of
ſome other bodies) The power ſhee
makes
uſe of to hinder a Vacuum, is not
1(as we have elſe-where alſo noted) any
ſuch
boundleſs thing as men have been
pleas
'd to imagine.
And the reaſon, why
in
the former Experiments, mentioned
in
favour of the Pleniſts, Bodies ſeem to
forget
their own Natures to ſhun a Va­
cuum
, ſeems to be but this; That in the
alleadged
caſes the weight of that Wa­
ter
that was either kept from falling or
impell
'd up, was not great enough to
ſurmount
the preſſure of the contiguous
Air
; which, if it had been, the Water
would
have ſubſided, though no Air could
have
ſucceeded.
For not to repeat that
Experiment
of Monſieur Paſchal (for­
merly
mention'd to have been try'd in a
Glaſs
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 ſay) we ſaw in
our
nineteenth Experiment, that when
the
preſſure of the ambient Air was ſuffi­
ciently
weaken'd, the Water would fall
out
apace at the Orifice even of a ſhort
Pipe
, though the Air could not ſucceed
into
the room deſerted by it.
And it were
not
amiſs if tryal were made on the tops
of
very high Mountains, to diſcover with
1what eaſe a Vacuum could be made near
the
confines of the Atmoſphere, where
the
Air is probably but light in compari­
ſon
of what it is here below.
But our
preſent
(three and thirtieth) Experiment
ſeems
to manifeſt, not onely that the
power
, exerciſ'd by Nature, to ſhun or re­
pleniſh
a Vacuum, is limited, but that it
may
be determin'd even to Pounds and
Ounces
: Inſomuch that we might ſay,
ſuch
a weight Nature will ſuſtain or will
lift
up to reſiſt a Vacuum in our Engine;
but
if an Ounce more be added to that
weight
, it will ſurmount Her ſo much
magnifi
'd deteſtation of Vacuities.
And
thus
, My Lord, our Experiments may
not
onely anſwer thoſe of the Pleniſts,
but
enable us to retort their Arguments
againſt
themſelves: ſince, if that be true
which
they alleadge, that, when Water
falls
not down according to its nature, in
a
Body wherein no Air can ſucceed to fill
up
the place it muſt leave, the ſuſpenſi­
on
of the Liquor is made Ne detur Vacu­
um
, (as they ſpeak) it will follow, that
if
the Water can be brought to ſubſide
in
ſuch a caſe, that deſerted ſpace may be
deem
'd empty, according to their own
Doctrine
; eſpecially, ſince Nature (as
1they would perſwade us) beſtirs her ſelf
ſo
mightily to keep it from being de­
ſerted
.
I hope I ſhall not need to reminde Your
Lordſhip
, that I have all this while been
ſpeaking
of a Vacuum, not in the ſtrict
and
Philoſophical ſenſe, but in that more
obvious
and familiar one that has been
formerly
declar'd.
And therefore I ſhall now proceed to
obſerve
in the laſt place, that our 33d Ex­
periment
affords us a notable proof of the
unheeded
ſtrength of that preſſure which
is
ſuſtain'd by the Corpuſcles of what we
call
the free Air, and preſume to be un­
compreſſ
'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 compreſſion then what is (at
leaſt
here below) Natural, or (to ſpeak
more
properly) ordinary to it, it bears ſo
ſtrongly
upon the Bodies whereunto it is
contiguous
, that a Cylinder of this free
Air
, not exceeding three Inches in Dia­
meter
is able to raiſe and carry up a
weight
, amounting to between ſixteen
and
ſeventeen hundred Ounces.
I ſaid,
1even in our Climate, becauſe that is tem­

perate
enough; and as far as my obſer­
vations
aſſiſt me to conjecture, the Air in
many
other more Northern Countries
may
be much thicker, and able to ſupport
a
greater weight: which is not to be
doubted
of, if there be no miſtake in
what
is Recorded concerning the Hollan­
ders
, that were forc'd by the Ice to Win­
ter
in Nova Zembla, namely, That
they
found there ſo condenſ'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.
Aere frigi­
do
exiſtente
tardius
mo­
ventur
Au­
tomata
quam
aere
caida,
adco
qui­
dem
ut Au­
tomaton

quod
Belgæ
in
Nova
Zembla

gentes
in æ­
dibus
ſuis
collocave­
runt
, omni­
no
à motis
ceſſaverit

etſi
multo
maius
toa­
dus
ei addidiſſent quam antea ferre ſolebat.
Varenius Geo: Genevat
111. Propo: 7. pag. 648.
I ſuppoſe Your Lordſhip will readily
take
notice, that I might very eaſily have
diſcourſed
much more fully and accuratly
then
I have done, againſt the common
pinion
touching Suction, and touching na­
tures
hatred of a Vacuum. But I was willing
to
keep my ſelf to thoſe conſiderations
touching
theſe matters, that might be ve­
rifi
'd by our Engine it ſelf, eſpecially, ſince,
as
I ſaid at firſt, it would take up too much
time
to inſiſt particularly upon all the Re­
flections
that may be made even upon our
two
laſt Experiments.
And therefore,
1paſſing to the next, I ſhall leave it to your
Lordſhip
to conſider how far theſe tryals
of
ours will either confirm or disfavor
the
new Doctrine of ſeveral eminent Na­
turaliſts
, who teach, That in all motion
there
is neceſſarily a Circle of Bodies, as
they
ſpeak, moving together; and whe­
ther
the Circles in ſuch motion be an Ac­
cidental
or Conſequential thing or no.
TIs a known thing to thoſe that are con­

verſant
in the Hydroſtaticks, That
two
Bodies which in the Air are of equal
weight
, but of unequal bulk, as Gold,
for
inſtance and Iron, being afterwards
weighed
in Water, will loſe their Æqui­
librium
upon the change of the ambient
Body
, ſo that the Gold will ſink lower
then
the Iron; which, by reaſon of its
greater
bulk, has more Water to lift
or
diſplace, that it may ſink.
By Analogy
to
this Experiment, it ſeem'd probable,
that
if two weights did in our Engine
ballance
each other, when the Glaſs was
full
of Air; upon the exſuction of a
great
part of that Air, ſo notable a change
in
the conſiſtence of the ambient Body,
1would make them loſe their Æquili­
brium
.
Experi­
ment
34.
But being deſirous at the ſame time to
make
a tryal, for a certain Deſign that
needs
not here be mention'd, we took
for
one of our weights a dry Bladder,
ſtrongly
tyed at the Neck, and about
half
fill'd with Air (that being a weight
both
ſlight, and that would expand it
ſelf
in the evacuated Glaſs) and faſtning
that
to one part of our formerly menti­
on
'd exact ballance (which turns with the
32
d part of a Grain) we put a Metalline
counterpoiſe
into the oppoſite Scale; and
ſo
the two weights being brought to an
Æquilibrium, the ballance was convey'd
into
the Receiver, and ſuſpended from the
Cover
of it.
But before we proceed further, we muſt
note
, That preſently 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 Æ­
quilibrium
, yet ſo, that a little advantage
remain
'd on that ſide to which the Metal­
line
weight belong'd; they were again let
down
into the Receiver, which was pre­
ſently
made faſt with Plaiſter, and a hot
Iron
: Soon after which, before the Pump
1was employ'd, the Bladder ſeem'd again
a
little to preponderate.
Afterwards
the
Air in the Glaſs being begun to be
drawn
out, the Biadder began (according
to
the formerly mention'd Obſervations)
to
expand it ſelf, and manifeſtly to out­
weigh
the oppoſite weight, drawing
down
the Scale to which it was faſtned
very
much beneath the other, eſpecially
when
the Air had ſwell'd it to its full ex­
tent
.
This done, we very leiſurely let in the
external
Air; and obſerv'd, that upon
the
flagging of the Bladder, the Scale
whereto
it was faſtned, not onely by de­
grees
return'd to an Æquilibrium with the
other
, but at length was a little out­
weighed
by it.
But becauſe we ſuſpected there
might
have interven'd ſome unheeded
Circumſtance
in this laſt part of the Ex­
periment
, we would not preſently 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 ſink lower and lower for
divers
hours; wherefore, leaving the
Veſſel
cloſ'd up all night, we repair'd to it
1next Morning, and found the Bladder
fallen
yet lower.
As if the very ſubſtance
of
it, had imbibed ſome of the moiſture
wherewith
the Air (the Seaſon being ve­
ry
rainy) did then abound: As Lute­
ſtrings
, which are made likewiſe of the
Membranous
parts of Guts, ſtrongly
wreath
'd, are known to ſwell ſo much,
oftentimes
as to break in rainy and wet
weather
.
Which conjecture is the more to
beregarded
, becauſe congruouſly unto it
one
of the company having a little warm'd
the
Bladder, found it then lighter then
the
oppoſite weight.
But this muſt be
look
'd upon as a bare conjecture, till we
can
gain time to make further tryals about
it
.
In the mean while we ſhall adde, that
without
removing the Scales or the Co­
ver
of the Receiver, we again cauſ'd the
Air
to be drawn out (the weather conti­
ing
very moiſt) but found not any manifeſt
alteration
in the ballance; whether be­
cauſe
the Æquilibrium was too far loſt to
let
a ſmall change appear, we determine
not
.
But to make the Experiment with a
Body
leſs apt to be altered by the tempe­
rature
of the Air, then was the Bladder;
we
brought the Scales again to an Æqui-
1librium with two weights, whereof the
one
was of Lead, the other of Cork.
And
having
evacuated the Receiver, we obſer­
ved
, that both upon the exſuction, and
after
the return of the Air, the Cork did
manifeſtly
preponderate, and much more
a
while after the Air had been let in again,
then
whilſt it was kept out.
Wherefore,
in
the room of the Cork, we ſubſtituted
a
piece of Char-coal, as leſs likely to im­
bibe
any moiſture from the Air, but the
event
proved much the ſame with that
newly
related: So that this Experiment
ſeems
more liable to Caſualties then any,
excepting
one we have made in our En­
gine
.
And as it is difficult to prevent
them
, ſo it ſeems not very eaſie to diſ­
cover
the cauſes of them, whereof we
ſhall
therefore at preſent forbear mention­
ing
our Conjectures.
SOme Learned Mathematicians have of

late
ingenioùſly endeavored to reduce
Filters
to Siphons; but ſtill the true cauſe
of
the aſcenſion of Water, and other Li­
quors
, both in Siphons and in Filtration,
needing
(for ought we have yet found) a
clearer
Diſcovery and Explication, we
1were deſirous to try whether or no the
preſſure
of the Air might reaſonably be
ſuppoſ
'd to have either the principal, or at
leaſt
a conſiderable Intereſt in the raiſing
of
thoſe Liquors.
But becauſe we found
that
we could not yet ſo evacuate our Re­
ceiver
, but that the remaining Air,
though
but little in compariſon of the
exhauſted
, would be able to impell the
the
Water to a greater height then is
uſual
in ordinary Filtrations: we reſolved,
inſtead
of a Liſt of Cotton, or the like
Filtre
, to make uſe of a Siphon of Glaſs,
delineated
in the third Figure, conſiſt­
ing
of three pieces, two ſtraight, and
the
third crooked to joyn them toge­
ther
; whoſe Junctures were diligently
cloſ
'd, that no Air might finde entrance
at
them.
One of the Legs of this Si­
phon
was (as it ſhould be) ſomewhat
longer
then the other, and was pervious
at
the bottom of it onely, by a hole al­
moſt
as ſlender as a hair, that the
Water
might but very leaſurely drop
out
of it, leſt it ſhould all run out
before
the Experiment were compleat­
ed
.
The other and ſhorter Leg of
the
Siphon was quite open at the end,
and
of the ſame wideneſſe with the
1reſt of the Pipe, whoſe bore was about /4
of
an Inch.
The whole Siphon made
up
of theſe ſeveral pieces put together,
was
deſign'd to be about a Foot and a
half
long; that the remaining Air, when
the
Veſſel was exhauſted after the wont­
ed
manner, might not be able to impell
the
Water to the top of the Siphon;
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
Glaſs
Veſſel full of Water, and the up­
per
parts of it being faſten'd to the inſide
of
the Cover of the Receiver, we pro­
ceeded
to cloſe firſt, and then to empty
the
Veſſel.
Experi­
ment
35.
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
Siphon, as if the Experiment had been
performed
in the free Air.
But afterwards,
the
Bubbles (as had been apprehended)
began
to diſcloſe themſelves in the Wa­
ter
, and aſcending to the top of the Si­
phon
, imbodyed themſelves there into
one
, which was augmented little by little
by
the riſing of other bubbles that from
time
to time broke into it, but much
1 more by its own dilatation, which en-
creaſ
'd proportionably to the exſuction
that was made of the Air out of the Re-
ceiver
.
So that at length the Water in
the ſhorter Leg of the Siphonwas re-
duc
'd partly by the extraction of the am-
bient
Air, and partly by the expanſion
of the great Bubble at the upper part of
the Siphon, to be but about a Foot high,
if ſo much; wherby it came to paſs,
that the courſe of the Water in the Si-
phon
was interrupted, and that which re-
main
'd in the longer Leg of it, continu'd
ſuſpended there without dropping any
longer.
But upon the turning of the
Stop-cock, the outward Air (being t
into the Receiver) got into the Siphon by
the little hole at which the Water former-
ly
dropt out; and traverſing all the in-
cumbent
Cylinder of Water, in the form
of Bubbles, joyn'd it ſelf with that Air
that before poſlongs;eſlongs;'d the top of the Si-
phon
.
To prevent the inconveniences ariſing
from theſe Bubbles, two Glaſs Pipes, like
the former; were ſo placed; as to termi-
nate
together in the midſt of the Belly of
a Glaſs Viol, into whoſe Neck they
were carefully faſtned with Cement; and
1 then both the Viols and the Pipes being
(which was not the not done without difficulty)
totally fill'd with Water, the Siphon
deſcrib'd in the fifth Figure, was plac'd
with its ſhorter Leg in the Glaſs of Wa-
ter
, as formerly; and the Experiment be-
ing
proſecuted after the ſame manner,
much more Air then formerly was drawn
out, before the Bubbles diſclosing them-
ſelves
in the Water were able to diſturb
the Experiment; becauſe that in the ca-
pacity
of the Viol there was room enough
for them to ſtretch themſelves, without
depreſſing the Water below the ends of
the Pipes; and, during this time, the
Water continued to drop out of the pro-
pending
Leg of the Siphon.But at
length the Receiverbeing very much em-
pty
'd, the paſſage of the Water through
the Siphonceaſ'd, the upper ends of the
Pipes beginning to appear a little above
the remaining Water in the Viol, whoſe
dilated Air appear'd likewiſe to preſs
down the Water in the Pipes, and fill the
upper part of them.
And hereby the con-
tinuity
of the Water, and ſo the Expe-
riment
it ſelf being interrupted, we were
invited to let in the air again, which, ac-
cording
to its various proportions of
1 preſſure to that of the Air in the Viol
and the Pipes, did for a good while exhi-
bite
a pleaſing variety of Phaenomena,
which we have not now the leiſure to re-
cite
.
And though upon the whole mat-
ter
there ſeem'd little or no cauſe to
doubt, but that, if the Bubbles had not
diſturb'd the Experiment, it would mani-
feſtly
enough have appear'd that the
courſe of Water through Siphons de-
pends
upon the preſſure of the Air: yet
we reſolv'd, at our next leiſure and con-
veniency
, to try the Experiment again,
with a quantity of Water before freed
from Bubbles by the help of the ſame
Engine.
This occaſion I have had to take notice
of Siphons, puts me in minde of an odde
kinde of Siphon that I cauſ'd to be made
a pretty while ago; and which has been
ſince, by an Ingenious Man of Your ac-
quaintance
, communicated to divers o-
thers
.
This occaſion was this, An emi-
nent
Mathematician told me one day, that
ſome inquiſitive French Men (whoſe
Names I know not) had obſerv'd, That,
in caſe one end of a flender and perforated
Pipe of Glaſs be dipt in Water, the Li-
1quor will aſcend to ſome height in the
Pipe
, though held perpendicular to the
plain
of the Water.
And, to ſatisfie me
that he miſ-related not the Experiment,
he ſoon after brought two or three
ſmall
Pipes of Glaſs, which gave me the
opportunity of trying it: though I had
the
leſs reaſon to diſtruſt it, becauſe I re-
member
I had often in the long and flen-
der
Pipes of ſome Weather Glaſſas,
which I had cauſ'd to be made after a
ſomewhat
peculiar faſhion, taken notice
of the like aſcenſion of the Liquor,
though (preſuming it might be caſual) I
had made but litllereflection upon it.
But
after this tryal, beginning to ſuppoſe, that
though the Water in theſe Pipes that
were brought me, riſe not above a quar-
ter
of an Inch, (if near ſo high) yet, if
the Pipes were made flender enough, the
water might riſe to a very much greater
height; I cauſ'd ſeveral of them to be, by
a dexterous Hand, drawn out at the flame
of a Lamp, in one of which that was
almoſt incredibly flender, we found that
the Water asſended (as it were of it ſelf)
five Inches by meaſure, to the no ſmall
wonder of ſome famous Mathematicians,
who were Spectators of ſome of theſe
1Experiments.And this height the Wa-
ter
reach'd to, though the Pipe were held
in as erected a poſture as we could: For if
it were inclin'd, the Water would fill a
greater part of it, though not riſe higher
in it.
And we alſo found, that when the
inſide of the Pipe was wetted before-
hand
, the Water would riſe much better
then otherways: But we cauſ'd not all
our flender Pipes to be made ſtraight, but
ſome of them crooked, like Siphons: And
having immerſ'd the ſhorter Leg of one
of theſe into a Glaſs that held ſome fair
Water, we found, as we expected, that
the Water ariſing to the top of the Si-
phon
, though that were high enough, did
of it ſelf run down the longer Leg, and
continue running like an ordinary Siphon.
The cauſe of this aſcenſion of the Wa-
ter
, appear'd to all that were preſent ſo
difficult, that I muſt not ſtay to enumerate
the various Conjectures that were made
at it, much leſs to examine them; eſpe-
cially
, having nothing but bare Conje-
ctures
to ſubſtitute in the room of thoſe
I do not approve.
We try'd indeed, by
conveying a very flender Pipe and a ſmall
Veſſel of Water into our Engine, whe-
ther
or no the Exſuction of the ambient
1 Air would aſſiſt us to finde the cauſe of
the aſcenſion we have been ſpeaking of:
But though we imploy'd red Wine in-
ſtead
of Water, yet we could fearce cer-
tainly
perceive thorow ſo much Glaſs, as
was interpoſ'd betwixt our Eyes and the
Liquor
, what happen'd in a Pipe ſo flen-
der
, that the redneſs of the Wine was
ſcarce ſenſible in it.
But as far as we could
diſcern
, there happen'd no great altera-
tion
to the Liquor: which ſeem'd the leſs
ſtrange, becauſe the Spring of that Air
that might depreſs the Water in the Pipe,
was equally debilitated with that which
remain'd to preſs upon the ſurface of the
Water in the little Glaſs.
Wherefore, in
favor of his Ingenious Conjecture who
aſcrib'd the Phaenomenon, under conſide-
ration
to the greater preſſure made upon
the Water by the Air without the Pipe,
then by that within it, (where ſo much of
the Water (conſiſting perhaps of Corpu-
ſcles
more pliant to the internal ſurfaces of
the Air) was contiguous to the ſides) it
was ſhown, that in caſe the little Glaſs
Veſſel that held the Water, of which a
part aſcended into the flender Pipe, were
ſo cloſ'd, that a Man might with his mouth
ſuck the Air out of it, the Water would
1 immediately ſubſide in the ſmall Pipe.
And this would indeed infer, that it aſ-
cended
before onely by the preſſure of
the incumbent Air: But that it may
(how juſtly I know not) be objected,
that preadventure this would not hap-
pen
, in caſe the upper ende of the Pipe
were in a Vacuum: And that 'tis very
probable the Water may ſubſide, not
becauſe the preſſure of the internal Air
is taken off by Exſuction, but by reaſon
of the Spring of the external Air,
which impels the Water it findes in its
way to the Cavity deſerted by the
other Air, and would as well impell
the ſame Water upwards, as make it
ſubſide, if it were not now leiſure to exa-
mine
any further this Matter, I ſhall
onely minde Your Lordſhip, that if
You will proſecute this Speculation,
it will be pertinent to finde out likewiſe,
Why the ſurface of Water /as is manifeſt
in Pipes) uſes to be concave, being de-
preſſ
'd in the middle, and higher on eve-
ry
side? and Why in Quick-ſilver on the
contrary, not onely the ſurface is wont
1 to be very convex, or ſwelling, in the
middle; but if you dip the end of a flen-
der
Pipe in it, the ſurface of the Li-
quor
(as 'tis call'd) will be lower within
the Pipe, then without.
Which Phaeno-
mena
, whether, and how far, they may
be deduc'd from the Figure of the Mer-
curial
Corpuſcles, and the Shape of the
Springy Particles of the Air, I willingly
leave to be conſider'd.
SEveral ways we have met with pro-
poſ
'd, partly by the excellent Galileo,
and partly by other ingenious Writers,
to manifeſt that the Air is not devoid of
weight; ſome of theſe, require the previ-
ous
abſence of the Air to be weighed;
and others, the violent condenſation of it.
But if we could lift a pair of Scales above
the Atmoſphere, or place them in a Va-
cuum
, we might there weigh a parcel of
Air it ſelf, as here we do other Bodies in
the Air, becauſe it would there be heavi-
er
then that which ſurrounds it, as are
groſſer
Bodies we commonly weigh, then
the medium or ambient Air.
Where-
fore
, though we have above declin'd to
affirm, that our Receiver, when empty-
1ed, deſerves the name of a true Vacuum,
and though we cannot yet perfectly free
it from Air it ſelf, yet we thought fit to

try how far the Air would manifeſt its
gravity in ſo thin a medium, as we could
make in our Receiver, by evacuating it.
We cauſ'd then to be blown at the Flame
of a Lamp, a Glaſs-bubble of about
the bigneſs of a small Hen egge, and of
an Oval form, ſave that at one end there
was drawn out an exceeding flender Pipe,
that the Bubble might be ſeal'd up, with
as little rarifaction as might be, of the
Air included in the great or ovall Cavi-
ty
of it.
This Glaſs being ſeal'd, was fa-
ſtened
to one of the Scales of the exact
pair of Ballances formerly mention'd;
and being counterpoiſ'd with a weight of
Lead, was convey'd into the Receiver,
and cloſ'd up in it.
The Beam appearing
to continue Horizontal, the Pump was ſet
awork, and there ſcarce paſt above two
or three Exſuctions of the Air, before
the Ballance loſt its Aequilibrium, and
began to incline to that ſide on which
the Bubble was; which, as the Air was
further and further drawn out, did mani-
feſtly
more and more preponderate, till
he that pump'd began to grow weary of
1 his Imployment: after which the aire be-
ing
leaſurely let in againe, the ſcales by
degrees returned to their former Aequili-
brium
.
After that we tooke them out, and
caſting into that ſcale to which the lead
belong'd three quarters of a grain, we
convey'd the ballance into the Recei-
ver
, which being cloſed up, and exhau-
ſted
as before, we obſerv'd, that as the
aire was drawne out more and more, ſo
the glaſſe bubble came neerer and neer-
er
to an Aequilibrium with the other
weight, till at length the beame was
drawne to hang horizontall; which (as
we had found by another tryall) wee
could not bring it to do, when a quar-
ter
of a Graine more was added to
the ſcale, to which the lead belong'd:
though it ſeem'd queſtionleſſe, that if
wee could have perfectly empty'd the
Receiver of the contain'd aire, that in-
cluded
, in the bubble would have weigh-
ed
above a grain, notwithſtanding its
having been probably ſomewhat Rari-
fy
'd by the flame by the help of which,
the bubble was ſeald up.
Let us adde,
that on the regreſſe of the excluded
air, the Lead, and the weight caſt into the
1ſame ſcale, did againe very much pre-
ponderate
.
Experi-
ment
36.
We likewiſe convey'd into the Re-
ceiver
, the ſame bubble, open'd at
the end of the flender pipe above men-
tioned
, but having drawne out the aire,
after the accuſtomed manner, we found
not as before, the bubble to out-weigh
the oppoſite lead, ſo that by the help
of our Engine, we can weigh the Aire,
as we weigh other Bodies, in its na-
turall
or ordinary conſiſtence, without
at all condenſing it: Nay, which is re-
markable
, having convey'd a Lamb's
bladder about halfe full of Aire into the
Receiver, wee obſerved, that though
upon the drawing out of the ambient
aire
the impriſoned Air ſo expended
it ſelf, as to diſtend the Bladder ſo, as to
ſeem ready to break it, yet this rarified
Air did manifeſtly depreſs the Scale
whereunto it was annexed.
Another thing, we muſt not forget to
mention, that happend to us, whil'ſt we were
making tryals concerning the weight of the
Air; namely, That having once cauſ'd the
1 Pump to be ſomewhat obſtinately ply'd,
to diſcover the better what may be ex-
pected
from the thinneſs of the medium
in this Experiment; the Impriſon'd Air
broke its brittle Priſon, and throwing the
greateſt part of it againſt the ſide of the
Receiver, daſh'd it againſt that thick Glaſs
into a multitude of pieces.
Which Acci-
dent
I mention, partly that it may con-
firm
what we deliver'd in our Reflections,
upon the firſt Experiment, where we con-
ſider
'd what would probably be done by
the Spring of Air Impriſon'd in ſuch
Glaſſes, in caſe the ballancing preſſure of
the ambient Air were withdrawn; and
partly, that we may thence diſcern of how
cloſe a Texture Glaſs is, ſince ſo very
thin a film of Glaſs (if I may ſo call it)
prov'd ſo impervious to the Air, that it
could not get away through the Pores,
but was forc'd to break the glaſs in pieces
to free it ſelf; and this, notwithſtanding
the time and advantage it had to try to
get out at the Pores.
And this I mention,
that neitherour Experiments, nor thoſe
of divers Learned Men, might receive
any prejudice from an Experiment which
I happen'd to make divers years ago, and,
which having been ſo much taken notice
1 of by curious Men, may be drawn to
countenance their erroneous Opinion, who
would fain perſwade us, That Glaſs is
penetrable by Air properly ſo called.
Our
Experiment was briefly this: We were
diſtilling a certain ſubſtance, that much a-
bounded
with ſubtle Spirits and volatile
Salt, in a ſtrong Earthen-veſſel of an un-
uſual
ſhape, to which was luted a large
Receiver, made of the courſer ſort of
Glaſs, (which the Trades-men are wont
to call Green-glaſs) but in our abſence,
the Fire, though it were to be very ſtrong,
was by the negligence or miſtake of thoſe
we appointed to attend it, ſo exceſſively
increaſ'd, that when we came back to the
Fornace we found the Spirituous and Sa-
line
Corpuſcles pour'd out (if I may ſo
call it) ſo hot, and ſo copiouſly into the
Receiver, that they made it all opacous,
and more likely to flie in pieces, then fit
to be touch'd.
Yet, being curious to ob-
ſerve
the effects of a Diſtillation, prſe-
cuted
with ſo intenſe and unuſual degree
of heat, we ventur'd to come near, and
obſerv'd among other things, that on the
out-ſide of the Receiver, at a great di-
ſtance
from the juncture, there was ſetled
a round whitiſh Spot or two, which at
1firſt we thought might be ſome ſtain up­
on
the Glaſs; but after, finding it to
be
in divers Qualities like the Oyl,
and
Salt of the Concrete we were Di­
ſtilling
, we began to ſuſpect that the
moſt
ſubtle and fugitive parts of the im­
petuouſly
aſcending Steams, had pene­
trated
the ſubſtance (as they ſpeak) of
the
Glaſs, and by the cold of the am­
bient
Air were condenſ'd on the ſur­
face
of it.
And though we were ve­
ry
backward to credit this ſuſpition, and
therefore
call'd in an Ingenious Perſon
or
two, both to aſſiſt us in the Ob­
ſervation
, and have Witneſs of its
vent
, we continued a while longer to
watch
the eſcape of ſuch unctuous Fumes,
and
upon the whole matter unanimouſly
concluded
, That all things conſider'd,
the
ſubtle parts of the diſtill'd matter
being
violently agitated, by the exceſ­
ſive
heat had paſſ'd through the Pores
of
the Glaſs, widen'd by the ſame heat.
But this having never happen'd but
once
in any of the Diſtillations we have
either
made or ſeen, though theſe be
not
a few, it is much more reaſonable
to
ſuppoſe, that the perviouſneſs of
our
Receiver to a Body much more
1ſubtle then Air, proceeded partly from
the
looſer Texture of that particular
parcel
of Glaſs the Receiver was made
of
(for Experience has taught us, that
all
Glaſs is not of the ſame compact­
neſs
and ſolidity) and partly from the
enormous
heat, which, together with
the
vehement agitation of the pene­
trant
Spirits, open'd the Pores of the
Glaſs
; then to imagine that ſuch a
ſubſtance
as Air, ſhould be able to per­
meate
the Body of Glaſs contrary to
the
teſtimony of a thouſand Chymical
and
Mechanical Experiments, and of
many
of thoſe made in our Engine,
ſpecially
that newly recited: Nay, by
our
fifth Experiment it appears, that
a
thin Bladder will not at its Pores
give
paſſage even to rarified Air.
And
on
this occaſion we will annex an Ex­
periment
, which has made ſome of
thoſe
we have acquainted with it,
doubt
, whether the Corpuſcles of the
Air
be not leſſe ſubtle then thoſe of
Water
.
But without examining here the
reaſonableneſſe
of that doubt, we will
proceed
to recite the Experiment it ſelf,
which
ſeems to teach, That though Air,
1when ſufficiently compreſſ'd, may per­
chance
get entrance into narrower holes
and
crannies then Water; yet unleſs the
Air
be forc'd in at ſuch very little holes,
it
will not get in at them, though they
may
be big enough to let Water paſs
through
them.
The Experiment then was this: I took
a
fair Glaſs Siphon, the lower end of
whoſe
longeſt Leg was drawn by degrees
to
ſuch a ſlenderneſs, that the Orifice, at
which
the Water was to fall out, would
hardly
admit a very ſmall Pin: This Si­
phon
being inverted, the matter was ſo
order
'd, that a little Bubble of Air was
intercepted
in the ſlendereſt part of the
Siphon, betwixt the little hole newly men­
tion
'd, and the incumbent Water, upon
which
, it came to paſs, that the Air be­
ing
not to be forc'd through ſo narrow a
paſſage
, by ſo 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
pleaſ
'd to let it ſtay in that narrow place:
whereas
, when by blowing a little at the
wider
end of the Siphon, that little par­
cel
of Air was forc'd out with ſome Wa­
ter
, the remaining Water, that before
1continu'd ſuſpended, began freely to drop
down
again as formerly.
And if you
take
a Glaſs Pipe, whether it be in the
form
of a Siphon, or no, that being for
the
moſt part of the thickneſs of a Mans
Finger
, is yet towards one end ſo ſlen­
der
, as to terminate in a hole almoſt as
ſmall
as a Horſe-hair; and if you fill this
Pipe
with Water, you will finde that Li­
quor
to drop down freely enough tho­
row
the ſlender Extream: But if you then
invert
the Pipe, you will finde that the
Air
will not eaſily get in at the ſame hole
through
which the Water paſſ'd.
For in
the
ſharp end of the Pipe, ſome Inches
of
Water will remain ſuſpended, which
'tis probable would not happen, if the
Air
could get in to ſucceed it, ſince if the
hole
were a little wider, the Water would
immediatly
ſubſide.
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
ſeems to happen for ſome other rea­
ſon
, then becauſe the Air ſucceeds it at
the
upper and narrow Orifice, ſince all the
ſlender
part of the Pipe, and perhaps
ſome
Inches more, will continue full of
Water
.
1
And on this occaſion I remember, that
whereas
it appears by our fifth Experi­
ment
, That the Aërial Corpuſcles (ex­
cept
perhaps ſome that are extraordinari­
ly
fine) will not paſſe thorow the Pores
of
a Lambs Bladder, yet Particles of Wa­
ter
will, as we have long ſince obſerv'd,
and
as may be eaſily try'd, by very cloſe­
ly
tying a little Alcalizate Salt (we uſ'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 ſtrain thorow the
Pores
of the Bladder Water enough to
diſſolve
the Salt into a Liquor.
But I ſee I am ſlipt into a Digreſſion,
wherefore
I will not examine, whether,
the
Experiment I have related, proceed­
ed
from hence, That the ſpringy Texture
of
the Corpuſcles of the Air, makes
them
leſs apt to yield and accommodate
themſelves
eaſily to the narrow Pores of
Bodies
, then the more flexible Particles
of
Water; or whether it may more pro­
babiy
be aſcrib'd to ſome other Cauſe.
Nor will I ſtay to conſider how far we may
hence
be aſſiſted to gheſs at the cauſe of
the
aſcenſion of Water in the ſlender
1Pipes and Siphons formerly mention'd,
but
will return to our Bubble; and take
notice
, That we thought fit alſo to en­
deavor
to meaſure the capacity of the
Bubble
we had made uſe of, by filling
it
with Water, that we might the better
know
how much Water anſwered in
weight
to 3/4 of a Grain of Air, but not­
withſtanding
all the diligence that was
uſed
to preſerve ſo brittle a Veſſel, it
broke
before we could perfect what we
were
about, and we were not then pro­
vided
of another Bubble fit for our
turn
.
The haſte I was in, My Lord, when I
ſent
away the laſt Sheet, made me forget
to
take notice to you of a Problem that
occurr
'd to my thoughts, upon the oc­
caſion
of the ſlow breaking of the Glaſs
Bubble
in our evacuated Receiver.
For
it
may ſeem ſtrange, ſince by our ſixth
Experiment
it appears, that the Air, when
permitted
, will by its own internal Spring
expand
it ſelfe twice as much as Mer­
ſennus
was able to expand it, by the
heat
even of a candent Æolipile: Yet
the
Elater of the Air was ſcarce able to
break
a very thin Glaſs Bubble, and ut-
1terly unable to break one ſomewhat thic­
ker
, within whoſe cavity it was impri­
ſon
'd; whereas Air pent up and agitated
by
heat is able to perform ſo much more
conſiderable
effects, that (not to mention
thoſe
of Rarefaction that are more obvi­
ous
) the Learned Jeſuit Cabæus (he that

writ
of the Load-ſtone) relates, That he
ſaw
a Marble Pillar (ſo vaſt, that three
men
together with diſplay'd arms could
not
imbrace it, and that 1000 Yoke of
Oxen
drawing it ſeveral ways with all
their
ſtrength, could not have torn it
aſſunder
) quite broken off in the midſt,
by
reaſon of ſome Wood, which hap­
pening
to be burnt juſt by the Pillar, the
heat
proceeding from the neighboring
Fire
, ſo rarified ſome Air or Spirituous
Matter
which was ſhut up in the cavities
of
the Marble, that it broke through the
ſolid
Body of the Stone to obtain room
to
expand it ſelf.
: Nicoi:
Cab
: lib: 4.
Meteo
I remember I have taken notice that
probably
the reaſon why the included Air
did
not break the hermetically ſeal'd Bub­
bles
that remain'd intire in our emptyed
Receiver
, was, That the Air, being ſome­
what
rarefied by the Flame imploy'd to
cloſe
the Glaſs, its Spring, upon the re-
1ceſs of the heat, grew weaker then before.
But though we reject not that gheſs, yet
it
will not in the preſent caſe ſerve the
turn
, becauſe that much ſmaller Glaſs
bubbles
exactly cloſ'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
aſſiſted
to ſalve this Problem, by conſi­
dering
that the heat does from within ve­
hemently
agitate the Corpuſcles of the
Air
, and adde its aſſiſtance to the Spring
they
had before, I ſhall not now examine:
ſince
I here but propoſe a Problem, and
that
chiefly that by this memorable Story
of
Cabæus, notice may be taken of the
prodigious
power of Rarefaction, which
hereby
appears capable of performing
ſtranger
things then any of our Experi­
ments
have hitherto aſcrib'd to it.
We ſhould hence, My Lord, imme­
diatly
proceed to the next Experiment,
but
that we think it fit, on this occaſion,
to
acquaint You with what ſome former
tryals
(though not made in our Engine)
have
taught us, concerning what we
would
have diſcover'd by the newly
mention
'd Bubble that broke.
And this
the
rather, becauſe (a great part of this
1letter ſuppoſing the gravity of the Aire)
it
will not be impertinent to determine
more
particularly then hitherto we have
done
, what gravity we aſcribe to it.
We tooke then an Æolipile made of
copper
, weighing ſix ounces, five drachms,
and
eight and forty graines: this being
made
as hot as we durſt make it, (for feare
of
melting the mettle, or at leaſt the So­
dar
) was removed from the fire and im­
mediately
ſtopped with hard wax that no
Aire
at all might get in at the little
hole
wont to be left in Æolipiles for the
fumes
to iſſue out at: Then the Æolipile
being
ſuffer'd leaſurely to coole was again
weighed
together with the wax that ſtopt
it
, and was found to weigh (by reaſon of
the
additionall weight of the wax) ſix
ounces
, ſixe drachmes, and 39 graines.
Laſtly, the wax being perforated without
taking
any of it out of the Scale, the
externall
Aire was ſuffered to ruſh in
(which it did with ſome noyſe) and then
the
Æolipile and wax, being againe
weighed
amounted to ſix ounces, ſix
drachmes
, and 50. graines.
So that the
Æolipile freed as farre as our fire could
free
it, from it's Aire, weighed leſſe then
1it ſelfe when repleniſhed with Air, full
eleven
graines.
That is, the Air contain­
able
within the cavity of the Æolipile
mounted
to eleven graines and ſomewhat
more
; I ſay ſomewhat more, becauſe of
the
particles of the Air, that were not
driven
by the fire out of the Æolipile.
And
by the way (if there be no miſtake
in
the obſervations of the diligent Mer­
ſennus
) it may ſeeme ſtrange that it ſhould
ſo
much differ from 2. or 3. of ours; in
none
of which we could rarifie the Air in
our
Æolipile (though made red hot almoſt
all
over, and ſo immediately plung'd into
cold
water) to halfe that degree which he
mentions
, namely to 70. times it's natu­
rall
extent, unleſſe it were that the Æo­
lipile
he imploy'd was able to ſuſtaine
a
more vehement heat then ours (which
yet
we kept in ſo great an one, that once
the
ſoder melting, it fell aſunder into the
two
Hemiſpheres it conſiſts of.)
The fore-mentioned way of weighing
the
Air by the help of an Æolipile, ſeems
ſomewhat
more exact then that which
Merſennus uſed, In that in ours the Æoli­
pile
was not weighed, till it was cold;
whereas
in his, being weighed red hot, it
1ſubject to looſe of it's ſnbſtance in the
cooling
, for (as we have elſewhere noted
on
another occaſion) Copper heated red
hot
is wont in the cooling to throw off
little
thin ſcales in ſuch plenty, that having
purpoſely
watcht a Copper Æolipile du­
ring
its refrigeration, we have ſeen the
place
round about it almoſt covered with
thoſe
little ſcales it had every way ſcat­
ter
'd: which, however they amount not
to
much, ought not to be over-looked,
when
'tis ſo light a body as Air, that is
to
be weighed.
We will not examine,
whether
the Æolipile in cooling may not
receive
ſome little increment of weight,
either
from the vapid or ſaline Steames
that
wander up and downe in the Air: But
we
will rather mention, that (for the grea­
ter
exactneſſe) we imployed to weigh our
Æolipile, both when fill'd onely with Air
and
when repleniſht with Water, a paire
of
ſcales that would turne (as they ſpeak)
with
the fourth part of a grain.
As to the proportion of weight be­
twixt
Air and Water, ſome learned men
have
attempted it by wayes ſo unaccurate
that
they ſeeme to have much miſtaken
it
.
For (not to mention the improbable
accounts
of Kepler and others.) The lear-
1ned and diligent Ricciolus, having pur­
poſely
endeavoured to inveſtigate this
proportion
by meanes of a thin blad­
der
, eſtimates the weight of the Air to
that
of the Water to be as one to ten
thouſand
, or thereabouts.
And indeed I re­
member
that having formerly, on a cer­
tain
occaſion, weighed a large bladder full
of
Air, and found it when the Air was all
ſqueeſed
out, to have contained fourteen
graines
of Air.
I found the ſame 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 almoſt as a graine to a
pound
, that is, as one to above 7600. To
this
we may adde, that on the other ſide,
Galileo himſelfe uſing 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 propoſed of
weighing
the Air by an Æolipile, ſeemes
by
great oddes more exact; and (as farre
as
we could gheſſe) ſeemed to agree well
enough
with the experiment made in our
Receiver
.
Wherefore it will be beſt to
truſt
our Æolipile in the enquiry we are
bout
, and according to our obſervations
the
water it contained amounting to one
1and twenty ounces and an halfe, and as
much
Air as was requiſite to fill it weigh­
ing
eleven graines, the proportion in gra­
vity
of Air to Water of the ſame bulk
will
be as one to 938. And though we
could
not fill the Æolipile with water, ſo
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
thoſe that are delighted with round
numbers
(as the phraſe is) will not be
much
miſtaken if they reckon water to be
neere
a thouſand times heavier than Air.
And (for further proof that we have made
the
proportion betwixt theſe two bodies
rather
greater then leſſer then indeed it is;
and
alſo to confirme our former obſerva­
tion
of the weight of the Air) we will adde,
That
, having another time put ſome Wa­
ter
into the Æolipile before we ſet 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 Æolipile 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,
1when it was let in, increaſ'd the weight of
the
Æolipile as much as before, namely,
Eleven
Grains; though there were alrea­
dy
in it twelve Drachmes and a half, be­
ſides
a couple of Grains of Water, which
remain
'd of that we had formerly put in­
to
it to drive out the Air.
Merſennus 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
leſs then of 1300 to 1. And conſe­
quently
, that the quantity of Air to a
quantity
of Water equiponderant there­
to
, is as 1300 to 1. But why we ſhould
relinquiſh
our own carefully repeated try­
als
, I ſee not.
Yet I am unwilling to re­
ject
thoſe of ſo accurate and uſeful a Wri­
ter
: And therefore ſhall propoſe a way
of
reconciling our differing Obſervations,
by
preſenting, that the diſcrepance be­
tween
them may probably ariſe from the
differing
conſiſtence of the Air at London
and
at Paris: For our Air being more cold
and
moiſt, then that which Your Lord­
ſhip
now breaths, may be ſuppoſ'd alſo
to
be a fourth or fifth part more heavy.
I
leave
it to be conſider'd, whether it be of
1any moment that our Obſervations were
made
in the midſt of Winter, whereas his
were
perhaps made in ſome warmer time
of
the Year.
But I think it were not
miſs
that, by the method formerly pro­
poſ
'd, the gravity of the Air were ob­
ſerv
'd both in ſeveral Countries, and in
the
ſame Country, in the ſeveral Seaſons
of
the Year and differing Temperatures of
the
Weather.
And I would give ſome­
thing
of value to know the weight of ſuch
an
Æolipile as ours full of air in the midſt
of
Winter in Nova Zembla, if that be
true
which we formerly took notice of,
namely
, That the Hollanders, who Win­
tered
there, found that Air ſo thick that
their
Clock would not go.
If Your Lordſhip ſhould now ask me,
if
I could not by the help of theſe, and
our
other Obſervations, decide the Con­
troverſies
of our Modern Mathematici­
ans
about the height of the Air or Atmo­
ſphere
, by determining how high it doth
indeed
reach: I ſhould anſwer, That
though
it ſeems eaſie enough to ſhew that
divers
Famous and Applauded Writers
have
been miſtaken in aſſigning the heigth
of
the Atmoſphere: Yet it ſeems very
difficult
preciſely to define of what height
1it is. And becauſe we have hitherto but
lightly
touch'd upon a matter of ſuch im­
portance
, we preſume it wil not be thought
impertinent
, upon this occaſion, to annex
ſomething
towards the Elucidation of
it
.
What we have already try'd and newly
ſet
down, allows us to take it for granted,
that
(at leaſt about London) the propor­
tion
of gravity betwixt Water and Air,
of
equal bulk, is as of a thouſand to
one
.
The next thing therefore that we are
to
enquire after, in order to our preſent
deſign
, is the difference in weight betwixt
Water
and Quick-ſilver: And though
this
hath been defin'd already by the Il­
luſtrious
Verulam, and ſome other inqui­
ſitive
Perſons, that have compar'd the
weight
of ſeveral Bodies, and caſt their
Obſervations
into Tables, yet we ſhall
not
ſcruple to annex our own tryals about
it
: Partly, becauſe we finde Authors
conſiderably
to diſ-agree; partly, becauſe
we
uſ'd exacter Scales, and a ſomewhat
more
wary method then others ſeem to
have
done: And partly alſo, becauſe ha­
ving
proſecuted our inquiry by two or
three
ſeveral ways; the ſmall difference
1between the events may aſſure us that we
were
not much miſtaken.
We took then a Glaſs Pipe, of the
form
of an inverted Siphon, whoſe ſhape
is
delineated in the ſixteenth Figure: And
pouring
into it a quantity of Quick ſilver,
we
held it ſo, that the ſuperficies of the
Liquor
, both in the longer and ſhorter
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
Siphon, till that was almoſt fill'd, we ob­
ſerv
'd the ſurface of the Quick-ſilver in
that
leg to be, by the weight of the Wa­
ter
, depreſſ'd, as from E to B; and in
the
ſhorter leg, to be as much impell'd
upward
as from F to G: Whereupon ha­
ving
formerly ſtuck marks, as well at the
point
B, as at the oppoſite point D, we
mealur
d both the diſtance DC to have
the
height of the Cylinder of Quick-ſil­
ver
, which was raiſ'd above the Point D
(level with the ſurface of the Quick-ſilver
in
the other leg) by the weight of the Wa­
ter
, and the diſtance BA which gave us
the
height of the Cylinder of Water.
So
that
the diſtance DC amounting to (2 12/54)
Inches
, and the height of the Water
mounting
(30 45/50) Inches; and the whole
1numbers on both ſides, which the annex­
ed
Fractions being reduc'd to improper
Fractions
of the ſame denomination, the
proportion
appear'd to be (the denomi­
nators
beng left out as equal on both ſides)
as
121 to 1665; or by reduction, as one
to
(13 92/121).
Beſides this unuſual way of determi­
ning
the gravity of ſome things, we mea­
ſur
'd the proportion betwixt Quick-ſilver
and
Water, by the help of ſo exact a bal­
lance
, as looſes its Æquilibrium by the
hundredth
part of a Grain.
But becauſe
there
is wont to be committed an over­
ſight
in weighing Quick-ſilver and Wa­
ter
, eſpecially if the Orifice of the Veſſel
wherein
they are put be any thing wide, in
regard
that men heed not that the ſurface
of
Water in Veſſels will be concave,
but
that of Quick-ſilver, notably convex
or
protuberant: To avoid this uſual over­
ſight
(I ſay) we made uſe of a glaſs 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 ſlender
neck
, wherein the concavity or convexity
of
a Liquor could not be conſiderable:
This
Glaſs weighing 23 1/2 Grains, we fill'd
1almoſt with Quick-ſilver, and faſtning a
mark
over againſt the middle of the pro­
tuberant
Superficies as near as our Eyes
could
judge, we found that the Quick­
ſilver
alone weighed 299 1/32 Grains: Then
the
Quick-ſilver being pour'd out, and
the
ſame Glaſs 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
ſilver
, is as one to (13 19/28): Though our Il­
luſtrious
Verulam (queſtionleſs not for
want
of Judgement or Care, but of ex­
act
Inſtruments) makes the proportion
betwixt
thoſe two Liquors to be greater
then
of 1 to 17. And to adde, that up­
on
the by, ſince Quick-ſilver and well
rectified
Spirit of Wine, are (how juſtly
I
ſay not) accounted, the one the hea­
vieſt
, and the other the lighteſt of Li­
quors
; we thought to fill in the ſame
Glaſs
, and with the ſame Scales to ob­
ſerve
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, (ſuch as was ours) and
common
Water, is as betwixt 1 and (1 44/171)
1
We might here take occaſion to ad­
mire
, that though Water (as appear'd by
the
Experiment formerly mention'd of
the
Pewter Veſſel) ſeems not capable of
any
conſiderable condenſation, and ſeems
not
to have interſperſ'd in it any ſtore of
Air
; yet Quick-ſilver, of no greater bulk
then
Water, ſhould weigh near fourteen
times
as much.
But having onely point­
ed
at this as a thing worthy of conſidera­
tion
, we will proceed in our inquiry after
the
heigth of the Atmoſphere: And to
avoid
the trouble of Fractions, we will
aſſume
that Quick-ſilver is fourteen times
as
heavy as Water, ſince it wants ſo little
of
being ſo.
Wherefore having now given us the
proportion
of Air to Water, and Water
to
Quick-ſilver, it will be very eaſie to
finde
the proportion betwixt Air and
Quick-ſilver
, in caſe we will ſuppoſe the
Atmoſphere
to be uniformly of ſuch a
conſiſtence
as the Air we weighed here
below
.
For ſince our Engine hath ſuffi­

ciently
manifeſted that 'tis the Æquili­
brium
with the external Air, that in the
Torricellian Experiment keeps the Quick­
ſilver
from ſubſiding; And ſince, by our
accurate
Experiment formerly mention'd,
1it appears that a Cylinder of Mercury,
able
to ballance a Cylinder of the whole
Atmoſphere
, amounted to near about
thirty
Inches; and ſince, conſequently
we
may aſſume the proportion of Quick­
ſilver
to Air to be as fourteen thouſand to
one
; it will follow, that a Cylinder of
Air
, capable to maintain an Æquilibrium,
with
a Mercurial Cylinder of two Foot
and
an half in height, muſt amount to
35000
Feet of our Engliſh Meaſure;
and
conſequently (reckoning five Foot
to
a Geometrical Pace, and one thouſand
ſuch
Paces to a Mile) to ſeven full
Miles
.
But this (as we lately intimated) pro­
ceeds
upon the ſuppoſition, that the Air
is
every where of the ſame conſiſtence
that
we found it near the ſurface of the
Earth
; but that cannot with any ſafety
be
concluded, not onely for the reaſon I
finde
to have been taken notice of by the
Antients
, and thus expreſt in Seneca:
Omnis
Aër (ſays he) quo propior eſt terris

hoc craſsior; quemadmodum in aqua & in
omni
humore fæx ima eſt, it a in Aëre ſpiſ­
ſißima
quæ〈qué〉 deſidunt; but much more,
becauſe
the ſpringy Texture of the Aërial
Corpuſcles
, makes them capable of a
1very great compreſſion, which the weight
of
the incumbent part of the Atmo­
ſphere
is very ſufficient to give thoſe that
be
undermoſt and near the ſurface of the
Earth
.
And if we recall to minde thoſe
former
Experiments, whereby we have
manifeſted
, That Air, much rarefied with­
out
heat, may eaſily 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 uſually poſ­
ſeſſes
here below; How can it be demon­
ſtrated
that the Atmoſphere may not, for
ought
we know, or at leaſt for ought can
be
determin'd by our Statical and Mecha­
nical
Experiments, riſe to the height of
Five
and twenty German Leagues, if not
of
ſome hundred of common Miles?
4.
10.
And this conjecture it ſelf may appear
very
injurious to the height whereunto
Exhalations
may aſcend, if we will allow

that
there was no miſtake in that ſtrange
Obſervation
made at Tolous in a clear
Night
in Auguſt, by the diligent Ma­
thematician
Emanuel Magnan, and thus
Recorded
by Ricciolus, (for I have not at
hand
the Authors own Book) Vidit (ſays
he
) ab hor a undecima poſt meridiem uſ〈qué〉 ad
1mediam noctem Lunâ infra horizontem
poſitâ
, nubeculam quandam lucidam prope
Meridianum
fere uſque ad Zenith diffuſam
quæ
conſider at is omnibus non poter at niſi à
ſole
illuminari; ideoque altior eſſe debuit
tota
umbr a terræ.
Addit (continues Ricci­
olus
) ſimile quid eveniſſe Michaeli Angelo
Riccio
apud Sabinos verſanti nempe viro
in
Matheſi eruditiſsimo.
Various Obſervations made at the
feet
, tops, and interjacent parts of high
Mountains
, might perchance ſomewhat
aſſiſt
us to make an eſtimate in what pro­
portion
, if in any certain one, the higher
Air
is thicker then the lower, and gheſs
at
the diſ-form conſiſtence, as to laxity
and
compactneſs of the Air at ſeveral
diſtances
from us.
And if the difficul­
ties
about the refractions of the Celeſtial
Lights
, were ſatisfactorily determin'd,
that
might alſo much conduce to the pla­
cing
due limits to the Atmoſphere (whoſe
Dimenſions
thoſe Obſervations about
Refractions
ſeem hitherto much to con­
tract
.) But for the preſent we dare not
pronounce
any thing peremptorily con­
cerning
the height of it, but leave it to
further
inquiry: contenting our ſelves to
have
manifeſted the miſtake of divers
1eminent Modern Writers, who will not
allow
the Atmoſphere to exceed above
two
or three Miles in height (as the Fa­
mous
Kepler will not the Aër refractivus)
and
to have rendred a reaſon why in the
mention
we made in the Notes upon the
firſt
Experiment, touching the height of
the
Atmoſphere, we ſcrupled not to ſpeak
of
it, as if it might be many Miles high.
WE will now proceed to recite a

Phænomenon, which, though
made
amongſt the firſt, we thought fit
not
to mention till after many others, that
we
might have the opportunity to ob­
ſerve
as many Circumſtances of it as we
could
, and ſo preſent Your Lordſhip at
once
, moſt of what we at ſeveral times
have
taken notice of concerning ſo odde
a
Phænomenon.
Experi­
ment
37.
Our Engine had not been long finiſh'd,
when
, at the firſt leaſure we could ſteal
from
our occaſions to make tryal of it,
we
cauſ'd the Air to be pump'd out of
the
Receiver; and whil'ſt I was buſied in
entertaining
a Learned Friend that juſt
then
came to viſit me, an Ingenious By-
1ſtander, thought he perceiv'd ſome new
kind
of Light in the Receiver, of which
giving
me haſtily notice, my Friend and
I
preſently obſerv'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, almoſt
like
a faint flaſh of Lightening in the
Day-time
, and almoſt as ſuddenly did it
appear
and vaniſh.
Having, not with­
out
ſome amazement, obſerv'd divers
of
theſe 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
alſo, that by interpoſing a Cloak, or
any
opacous Body between the Receiver
and
the Window, though the reſt of the
Room
were ſufficiently enlightned, yet
the
flaſhes did not appear as before, un­
leſs
the opacous Body were remov'd.
But not being able on all theſe Circum­
ſtances
to ground any firm Conjecture
at
the cauſe of this ſurpriſing Phænome­
non
, as ſoon 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, ſo much as the
1leaſt glimmering of Light; whence we
inferr
'd, that the flaſh appearing in the
Receiver
, did not proceed from any new
Light
generated there, but from ſome
reflections
of the light of the Sun, or
other
Luminous Bodies plac'd without
it
; though whence that Reflection
ſhould
proceed, it poſ'd us to conje­
cture
.
Wherefore the next Morning, ho­
ping
to inform our ſelves better, we
went
about to repeat the Experiment,
but
though we could as well as former­
ly
exhauſt the Receiver, though the
place
wherein we made the tryal was the
very
ſame; and though other Circum­
ſtances
were reſembling, yet we could
not
diſcover the leaſt appearance of
Light
all that Day, nor on divers
thers
on which tryal was again fruitleſ­
ly
made; nor can we to this very time
be
ſure a Day before hand that theſe
Flaſhes
will be to be ſeen in our great
Receiver
.
Nay, having once found the
Engine
in a good humour (if I may
ſo
ſpeak) to ſhew this trick, and ſent
notice
of it to our Learned Friend
Doctor
Wallis, who expreſſ'd a great
1deſire to ſee this Phænomenon, though he
were
not then above a Bow-ſhoot off, and
made
haſte to ſatisfie his Curioſity; yet
by
that time he was come, the thing he
came
for was no longer to be ſeen; ſo
that
having vainly endeavored to exhibit
again
the Phænomenon in his preſence, I
began
to apprehend what he might think
of
me, when unexpectedly the Engine
preſented
us a flaſh, and after that a ſecond,
and
as many more, as ſuffic'd to ſatisfie
him
that we might very well confidently
relate
, that we have our ſelves ſeen this
Phænomenon, though not confidently pro­
miſe
to ſhew it others.
And this unſucceſsfulneſs whereto our
Experiment
is lyable, being ſuch, that by
all
our watchfulneſs and tryals, we could
never
reduce it to any certain Rules or
Obſervations
; ſince in all conſtitutions
of
the Weather, times of the Day, &c.
it
will ſometimes anſwer, and ſometimes
diſ-appoint
our Expectations; We are
much
diſcourag'd from venturing to frame
an
Hypotheſis to give an account of it:
which
if the Experiment did conſtantly
ſucceed
, might the more hopefully be at­
tempted
; by the help of the following
Phænomena laid together: ſome of them
1produc'd upon tryals purpoſely made
to
examine the validity of the conjectures,
other
tryals had ſuggeſted.
Firſt then we obſerv'd, that the Appa­
rition
of Light may be made as well by
Candle-light
, as by Day-light; and in
whatever
poſition 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
Veſſel.
Next, we noted that the flaſh appears
immediately
upon the turning of the
Key
, to let the Air out of the Receiver
into
the empty'd Cylinder, in ſo 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
hauſted
(whereby it came to paſs that the
Air
did rather deſcend, then ruſh into the
Cylinder
) the often mention'd flaſh ap­
pear
'd to our eyes.
Yet, we further obſerv'd, that when in­
ſtead
of the great Receiver we made uſe
of
a ſmall Glaſs, not containing above a
pound
and a half of Water, the Phæno­
menon
might be exhibited though the
Stop-cock
were open, provided the
1Sucker were drawn nimbly down.
We noted too, that when we began to
empty
the Receiver, the appearances of
Light
were much more conſpicuous
then
towards the latter end, when little
Air
at a time could paſs out of the Re­
ceiver
.
We obſerv'd alſo, that when the Suc­
ker
had not been long before well Oyl'd,
and
inſtead of the great Receiver, the
ſmaller
Veſſel above-mention'd was em­
ploy
'd; We obſerv'd, I ſay, that then,
upon
the opening of the Stop-cock, as
the
Air deſcended out of the Glaſs in­
to
the empty'd Cylinder, ſo at the ſame
time
there aſcended out of the Cylinder
into
the Veſſel a certain Steam, which
ſeem
'd to conſiſt of very little Bubbles,
or
other minute Corpuſcles thrown up
from
the Oyl, rarefied by the attrition it
ſuffered
in the Cylinder.
For at the
ſame
time that theſe Steams aſcended
into
the Glaſs, ſome of the ſame kinde
manifeſtly
iſſued out like a little Pillar of
Smoke
at the Orifice of the Valve, when
that
was occaſionally open'd.
And theſe
Steams
frequently enough preſenting
themſelves
to our view, we found, by
expoſing
the Glaſs to a clear Light, that
1they were wont to play up and down
in
it, and ſo by their whiteiſhneſs, to
mulate
in ſome meaſure the apparition of
Light
.
For we likewiſe ſometimes found, by
watchful
obſervation, that when the
Flaſh
was great, not onely at the very
inſtant
the Receiver loſt of its tranſpa­
rency
, by appearing full of ſome kinde
of
whitiſh ſubſtance; but that for ſome
ſhort
time after the ſides of the Glaſs
continued
ſomewhat opacous, and
ſeem
'd to be darken'd, as if ſome
whitiſh
Steam adher'd to the inſide of
them
.
He that would render a Reaſon of
the
Phænomenon, whereof all theſe are
not
all the Circumſtances, muſt doe
two
things; whereof the one is diffi­
cult
, and the other little leſs then im­
poſſible
: For he muſt give an Ac­
count
not onely whence the appearing
whiteneſs
proceeds, but wherefore that
whiteneſs
does ſometimes appear and
ſometimes
not.
For our part, we freely confeſſe
our
ſelves at a loſſe about rendering
1a Reaſon of the leſs difficult part of the
Problem
: And though Your Lord­
ſhip
ſhould ev'n preſs us to declare what
Conjecture
it was, that the above-recited
Circumſtances
ſuggeſted to us, we ſhould
propoſe
the thoughts we then had, no
therwiſe
then as bare Conjectures.
In caſe then our Phænomenon had con­
ſtantly
and uniformly appear'd, we ſhould
have
ſuſpected it to have been produc'd
after
ſome ſuch manner as follows.
Firſt, we obſerv'd that, though that
which
we ſaw in our Receiver ſeem'd to
be
ſome kinde of Light, yet it was indeed
but
a whiteneſs which did (as hath alrea­
dy
been noted) opacate (as ſome ſpeak)
the
inſide of the Glaſs.
Next we conſider'd, that our com­
mon
Air abounds with Particles or little
Bodies
, capable to reflect the Beams of
Light
.
Of this we might eaſily give di­
vers
proofs, but we ſhall name but two:
The
one, that vulgar obſervation of the
Motes
that appear in Multitudes ſwim­
ming
up and down in the Air, when the
Sun-beams
ſhooting into a Room, or any
other
ſhady Place diſcover them, though
otherwiſe
the eye cannot diſtinguiſh them
1from the reſt of the Air: The other proof
we
will take from what we (and no doubt
very
many others) have obſerv'd, touch­
ing
the Illumination of the Air in the
Night
.
And we particularly remember,
that
, being at ſome diſtance from London
one
Night, that the People, upon a very
well-come
Occaſion, teſtified their Joy
by
numerous Bon-fires; though, by rea­
ſon
of the Interpoſition of the Houſes,
we
could not ſee the Fires themſelves, yet
we
could plainly ſee the Air all enlighten'd
over
and near the City; which argu'd,
that
the lucid Beams ſhot upwards from
the
Fires, met in the Air with Corpuſcles
opacous
enough to reflect them to our
Eyes
.
A third thing that we conſidered, was,
That
white may be produc'd (without
excluding
other ways, or denying inviſi­
ble
Pores in the ſolideſt Bodies) when
the
continuity of a Diaphanous Body
happens
to be interrupted by a great num­
ber
of Surfaces, which, like ſo many
little
Looking-glaſſes, do confuſedly re­
preſent
a multitude of little and ſeeming­
ly
contiguous Images of the elucid Body.
We ſhall not inſiſt on the explanation of
this
, but refer You for it to what we have
1ſaid in another Paper (touching Co­
lours
.) But the Inſtances that ſeem to
prove
it are obvious: For Water or whites
of
Eggs beaten to froth, do loſe their
tranſparency
and appear white.
And ha­
ving
out of one of our leſſer Receivers
carefully
drawn out the Air, and ſo order'd
it
, that the hole by which the Water was
to
get in, was exceeding ſmall, that the
Liquor
might be the more broken in its
paſſage
thorow it, we obſerv'd with plea­
ſure
, That, the Neck being held under
Water
, and the little hole newly men­
tion
'd being open'd, the Water that ruſh'd
in
was ſo broken, and acquired ſuch a mul­
titude
of new Surfaces, that the Receiver
ſeem
'd to be full rather of Milk then Wa­
ter
.
We have likewiſe found out, That
by
heating a lump of Cryſtal to a certain
degree
, and quenching it in fair Water, it
would
be diſcontinu'd by ſuch a multi­
tude
of Cracks, (which created new Sur­
faces
within it) that though it would not
fall
aſunder, but retain its former ſhape,
yet
it would loſe its tranſparency, and ap­
pear
white.
Upon theſe Conſiderations, My Lord,
and
ſome others, it ſeem'd not abſur'd to
imagine
, That upon the ruſhing of the Air
1out of the Receiver into the empty'd Cy­
linder
, the Air in the Receiver being ſud­
denly
and vehemently expanded, the Tex­
ture
of it was as ſuddenly alter'd, and the
parts
made ſo to ſhift places (and perhaps
ſome
of them to change poſtures) as du­
ring
their new and vehement Motion and
their
varied Scituation, to diſturb the
wonted
continuity and ſo the Diapha­
neity
of the Air; which (as we have alrea­
dy
noted) upon its ceaſing to be a tran­
ſparent
Body, without the interpoſition
of
colour'd things, muſt eaſily degene­
rate
into white.
Several things there were that made
this
Conjecture ſeem the leſs improba­
ble
.
As firſt, That the whiteneſs al­
ways
appear'd greater when the Exſucti­
on
began to be made, whil'ſt there was
ſtore
of Air in the Receiver, then when
the
Air was in great part drawn out.
And
next
, That, having exhauſted the Re­
ceiver
, and apply'd to the hole in the
Stop-cock
a large bubble of clear Glaſs, in
ſuch
a manner, that we could at pleaſure let
the
Air paſs out at the ſmall Glaſs into the
great
one, and eaſily fill the ſmall one with
Air
again, We obſerv'd with pleaſure,
1That upon the opening the paſſage be­
twixt
the two Glaſſes, the Air in the
ſmaller
having ſo much room in the great­
er
to receive it, the Diſſilition of that
Air
was ſo great, that the ſmall Viol
ſeem
'd to be full of Milk; and this Expe­
riment
we repeated ſeveral times.
To
which
we may adde, That, having pro­
vided
a ſmall Receiver, whoſe upper Ori­
fice
was ſo narrow that I could ſtop it with
my
Thumb, I obſerv'd, that when upon
the
Exſuction of the Air the capacity of
the
Glaſs appear'd white, if by a ſudden
removal
of my Thumb I let in the out­
ward
Air, that whiteneſs would imme­
diately
vaniſh.
And whereas it may be
objected
, That in the Inſtance formerly
mention
'd, Water turning from perſpi­
cuous
to white, there intervenes the Air,
which
is a Body of a Heterogeneous na­
ture
, and muſt turn it into Bubbles to
make
it loſe its tranſparency.
We may
borrow
an Anſwer from an Experiment
we
deliver in another Treatiſe, 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
moſt
in a moment, without the ſub-ingreſ­
ſion
of Air to turn them into Bubbles, ſo
1alter the diſpoſition of their inſenſible
parts
, as to become a white and conſiſtent
Body
.
And this happens not as in the
precipitation
of Benjamin, and ſome
ther
Reſinous Bodies, which being diſ­
ſolv
'd in Spirit of Wine, may, by the effu­
ſion
of fair Water, be turn'd into a ſeem­
ingly
Milky ſubſtance.
For this white­
neſs
belongs not to the whole Liquor, but
to
the Corpuſcles of the diſſolv'd Gum,
which
after a while ſubſiding leave the Li­
quor
tranſparent, themſelves onely re­
maining
white: Whereas in our caſe, 'tis
from
the vary'd texture of the whole for­
merly
tranſparent fluid Body, and not
from
this or that part that this whiteneſſe
reſults
: For the Body is white thorowout,
and
will long continue ſo; and yet may,
in
proceſs of time, without any addition,
be
totally reduc'd into a tranſparent Bo­
dy
as before.
But beſides the Conjecture inſiſted on
all
this while, we grounded another upon
the
following Obſervation, which was,
That
having convey'd ſome ſmoke into
our
Receiver plac'd againſt a Window, we
obſerv
'd, that upon the exſuction of the
Air
, the Corpuſcles that were ſwimming
in
it, did manifeſtly enough make the Re-
1ceiver ſeem more opacous at the very
moment
of the ruſhing out of the Air:
For
conſidering that the whiteneſs, whoſe
cauſe
we enquire of, did but ſometimes ap­
pear
, it ſeem'd not impoſſible but that at
ſuch
times the Air in the Receiver might
abound
with Particles, capable of re­
flecting
the Light in the manner requiſite
to
exhibit a white colour, by their being
put
into a certain unuſual Motion.
As
may
be in ſome meaſure illuſtrated by
this
, That the new motion of the freſhly
mention
'd Fumes, made the inſide of the
Receiver
appear ſomewhat darker then
before
: And partly by the nature of our
formerly
mention'd ſmoking Liquor,
whoſe
parts though they ſeem'd tranſpa­
rent
whil'ſt they compoſ'd a Liquor, yet
when
the ſame Corpuſcles, upon the un­
ſtopping
of the Glaſs, were put into a
new
motion, and diſpoſ'd after a new
manner
, they did opacate that part of the
Air
they mov'd in, and exhibited a great­
er
whiteneſs then that which ſometimes
appears
in our Pneumatical Veſſel.
Nor
ſhould
we content our ſelves with this ſin­
gle
Inſtance, to manifeſt, That little Bo­
dies
, which being rang'd after one manner,
are
Diaphanous and Colourleſs, may, by
1being barely agitated, diſperſ'd, and con­
ſequently
otherways rang'd, exhibite a
colour
, if we were not unwilling to rob
our
Collection of Experiments concern­
ing
Colours.
But, My Lord, I foreſee You may
make
ſome Objections againſt our pro­
poſed
gheſs, which perhaps I ſhall ſcarce
be
able to anſwer, eſpecially, if You in­
ſiſt
upon having me render a Reaſon why
our
Phænomenon appears not conſtant­
ly
.
I might indeed anſwer, that probably
it
would do ſo, if inſtead of our great
Receiver
we uſe ſuch a ſmall Viol as we
have
lately mention'd, wherein the Diſſi­
lition
of the Air being much greater, is
like
to be the more conſpicuous: Since I
remember
not that we ever made our try­
al
with ſuch ſmall Veſſels, without find­
ing
the expected whiteneſs to appear.
But
it
would remain to be explicated, why in
our
great Receiver the Phænomenon ſhould
ſometimes
be ſeen, and oftentimes not ap­
pear
.
And though that Conjecture which
we
laſt made ſhould not be rejected, yet if
we
were further preſſ'd to aſſign a reaſon
why
the Air ſhould abound with ſuch Par­
ticles
, as we there ſuppoſe, more at one
1time then another, we are not yet pro­
vided
of any better Anſwer, then this
general
one, That the Air about us,
and
much more that within the Receiver,
may
be much alter'd by ſuch cauſes as few
are
aware of: For, not to repeat thoſe
probable
Arguments of this Aſſertion
which
we have occaſionally mention'd
here
and there in the former part of this
Epiſtle
, we will here ſet down two or
three
Inſtances to verifie the ſame Propo­
ſition
.
Firſt, I finde that the Learned
Foſephus Acoſta, among other Judicious

Obſervations
he made in America, hath
this
concerning the Effects of ſome
Winds
; There are (ſays he) Winds which
naturally
trouble the Water of the Sea, and
make
it green, and black; others, clear as
Cryſtal
.
Next, we have obſerv'd, That
though
we conveyd into the Receiver our
Scales
, and the Pendula formerly men­
tion
'd, clean and bright; yet after the Re­
ceiver
had been empty'd, and the Air let in
again
, the gloſs or luſtre both of the one,
and
of the other, appear'd tarniſh'd by a
beginning
ruſt.
And in the laſt place, we
will
ſubjoyn an Obſervation we made
ſome
Years ago, which hath been heard
of
by divers Ingenious Men, and ſeen
1by ſome of them: We had, with pure
Spirit
of Wine, drawn a Tincture out of
a
certain Concrete which uſes to be rec­
koned
among Mineral Bodies; And this
Tincture
being very pure and tranſparent,
we
did, becauſe we put a great value upon
it
, put into a Cryſtal Viol which we care­
fully
ſtopp'd, and lock'd up in a Preſs
mong
ſome other things that we ſpecial­
ly
priz'd.
This Liquor being a Chy­
mical
Rarity, and beſides, very defecate
and
of a pleaſing Golden Colour; we
had
often occaſion to look upon it, and
ſo
to take notice, that one time it ſeem'd
to
be very much troubled, and not clear
as
it was wont to be: Whereupon we ima­
gined
, that though it would be ſomething
ſtrange
, yet it was not impoſſible that
ſome
Precipitation of the Mineral Cor­
puſcles
was then happening, and that
thence
the Liquor was opacated; but,
finding
after ſome 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 ſomewhat wondered at it,
and
locking it up again in the ſame Preſs,
we
reſolved to obſerve, both whether
the
like changes would again appear in
1our Tincture; and whether in caſe they
ſhould
appear, they would be aſcribable
to
the alterations of the Weather.
But
though
, during the greateſt part of a Win­
ter
and a Spring, we took pleaſure to ob­
ſerve
, how the Liquor would often grow
turbid
, and after a while clear again: Yet
we
could not finde that theſe Mutations
depended
upon any that were manifeſt in
the
Air, whieh would be often dark and
clouded
, when the Tincture was clear and
tranſparent
; as on the other ſide, in clear
Weather
the Liquor would appear ſome­
times
troubled, and more opacous.
So
that
being unable to give an account of
theſe
odde changes in our Tincture (which
we
ſuppoſe we have not yet loſt, though
we
know not whether it have loſt its fickle
Nature
) either by thoſe of the Air, or
any
thing elſe that occurr'd to our
thoughts
; we could not but ſuſpect that
there
may be in divers Bodies, as it were
Spontaneous
Mutations, that is, ſuch
changes
as depend not upon manifeſt
Cauſes
.
But, My Lord, what has been
all
this while ſaid concerning our Phæno­
menon
, is offer'd to You, not as contain­
ing
a ſatisfactory Account of it, but to
aſſiſt
You to give Yourſelf one.
1
WE took a Glaſs Veſſel, open

at
the top, and into it we put
a
mixture of Snow and common Salt
(ſuch a mixture as we have in another
Treatiſe
largely diſcourſed of) and in­
to
the midſt of this mixture we ſet a
Glaſſe
, of a Cylindrical form, cloſely
ſtopp
'd at the lower end with Plaiſter,
and
open at the upper, at which we
fill
'd it with common Water.
Theſe
things
being let down into the Recei­
ver
, and the Pump being ſet awork,
the
Snow began to melt ſomewhat fa­
ſter
then we expected; whether upon
the
account of the Exſuction of the
Air
, or becauſe there was but little of
the
Snow, or whether for any other
Reaſon
, it appeared doubtfull.
But
however
, by that time the Receiver
had
been conſiderably exhauſted, which
was
done in leſſe then 1/4 of an hour,
we
perceived the Water near the bot­
tom
of the Glaſs Cylinder to Freeze,
and
the Ice by a little longer ſtay, ſeem'd
to
encreaſe, and to riſe ſomewhat higher
1then the ſurface of the ſurrounding Li­
quor
, where into almoſt all the Snow and
Salt
were reſolv'd.
The Glaſs being ta­
ken
out, it appear'd that the Ice was as
thick
as the inſide of the Glaſs it fill'd,
though
into that I could put my Thumb.
The upper ſurface of the Ice was very
concave
, which whether it were due to
any
unheeded accident, or to the exſu­
ction
of the Air, we leave to be deter­
min
'd by further tryal.
And laſtly, the
Ice
held againſt the Light, appear'd not
deſtitute
of Bubbles, though ſome By­
ſtanders
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 alſo another time in
one
of our ſmall Receivers, with not un­
like
ſucceſs.
Experi­
ment
38.
And on this occaſion, My Lord, give
me
leave to propoſe a Problem, which
ſhall
be this: Whence proceeds that
ſtrange
force that we may ſometimes ob­
ſerve
in frozen Water, to break the Bo­
dies
that Impriſon it, though hard and ſo­
lid
?
That there is ſuch a force in Wa­
ter
expoſ'd to Congelation, may be ga­
ther
'd not onely from what may be often
obſerv
'd in Winter, of the burſting of
1Glaſſes too cloſe ſtopp'd, fill'd with Wa­
ter
or aqueous Liquors, but by Inſtances
as
much more conſiderable as leſs obvi­
ous
.
For I remember, that an Ingenious
Stone-cutter
not long ſince complain'd to
me
, That ſometimes, through the negli­
gence
of Servants, the Rain being ſuffer­
ed
to ſoak into Marble Stones, the ſuper­
vening
violent Froſts would burſt the
Stones
, to the Profeſſors no ſmall dam­
age
.
And I remember another Trades­
man
, in whoſe Houſe I had Lodgings, was
laſt
Winter complaining, that even Im­
plements
made of Bell-metal, being care­
leſly
expoſ'd to the wet, have been broken
and
ſpoil'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
theſe
Relations, we can adde one of the

formerly
mention'd Cabæus's, whereby
they
not onely may be confirm'd, but are
ſurpaſſ
'd: For he tells us, That he ſaw a
huge
Veſſel of exceeding hard Marble,
ſplit
aſunder by congel'd Water, whoſe
Rarefaction
, ſays our Author, prov'd ſo
vehement
, that the hardneſs of the Stone
yielded
to it; and ſo a Veſſel was broken,
which
would not have been ſo by 100
1Yoke of Oxen drawing it ſeveral ways. I
know
, My Lord, that to ſolve this Pro­
blem
, it will be ſaid, That Congelation
does
not (as is commonly, but erroneouſly
preſum
'd) reduce water into leſs room
then
it poſſeſſ'd before, but rather makes
it
take up more.
And I have elſewhere
prov
'd by particular Experiments, That
whether
or no Ice may be truly ſaid to be
Water
rarefi'd (for that ſeems queſtion­
able
) it may be ſaid to take up more room
then
the Water did before Glaciation.
But though we grant that freezing makes
Water
ſwell, yet, how Cold (which in
Weather-Glaſſes
manifeſtly condences
the
Air) ſhould expand either the Water,
or
the intercepted Air ſo forcibly, as to
perform
ſuch things as we have newly re­
lated
, will yet remain a Problem.
In . 4.
WE took an Oval Glaſs, clear and

(leaſt it ſhould break) pretty
ſtrong
, with a ſhort Neck at the obtuſer
end
, through this Neck, we thruſt almoſt
to
the bottom, a Pipe of Glaſs, which was
cloſely
Cemented to the newly mention'd
Neck
, the upper part of which Pipe,
was
drawn in ſome places more ſlender
1then a Crows Quill, that the changes of
the
Air in that.
Glaſs Egge might be the
more
conſpicuous; Then there was con­
vey
'd into the Glaſs five or ſix Spoon­
fulls
of Water, part of which, by blow­
ing
Air into the Egge, was raiſ'd into the
above-mention
'd ſlender part of the Pipe,
ſo
that the Water was interpoſ'd between
the
external Air, and that included in the
Egge
.
This Weather-glaſs (delineated
in
the fourteenth Figure) was ſo plac'd,
and
cloſ'd up in the cavity of one of our
ſmall
Receivers, that onely the ſlender
part
of the Pipe, to the heigth of four
or
five Inches, paſſing thorow a hole in
the
Cover, remain'd expoſ'd to the open
Air
.
Experi­
ment
39.
The Pump being ſet a work, upon
the
Exſuction of the Air, the Water in
the
Pipe deſcended about a quarter of an
Inch
, and this upon two or three reitera­
ted
tryals; which ſeem'd ſufficiently to
argue
that there was no heat produc'd in
the
Receiver upon the Exſuction of the
Air
: For even a little heat would pro­
bably
have been diſcover'd by that Wea­
ther-glaſs
, ſince upon the bare applica­
tion
of my hand to the outſide of the
Receiver
, the warmth having after ſome
1time been communicated or propagated
through
both the Glaſſes, and the inter­
val
betwixt them to the Impriſon'd Air,
did
ſo rarifie that, as to inable it, by preſ­
ſing
upon the ſubjacent Water, to impel
that
in the Pipe very many times as far as
it
had fallen downwards upon the Exſucti­
on
of the Air.
Yet ſhall not we conclude, that in the
cavity
of the Receiver the cold was great­
er
after the Exſuction of the Air then be­
fore
.
For if it be demanded what then could
cauſe
the fore-mention'd ſubſiding of the
Water
?
it may be anſwered, That pro­
bably
it was the reaching of the Glaſs
Egge
, which, upon the Exſuction of the
ambient
Air, was unable to reſiſt alto­
gether
as much as formerly the preſſure of
the
included Air, and of the Atmoſphere,
which
by the intervenſion of the Water,
preſſ
'd upon its concave ſurface: Which
ſeem
'd probable, as well by what was
bove
deliver'd, in the Experiment about
the
breaking of the Glaſs by the force of
the
Atmoſphere; as by this notable Cir­
cumſtance
(which we divers times ob­
ſerv
'd) That when by drawing the Air out
of
the Receiver, the Water in the Pipe
1was ſubſided, upon the readmiſſion of the
external
Air to preſs againſt the convex
ſurface
of the Egge, the Water was pre­
ſently
re-impell'd to its former height:
Which
would perhaps appear leſs ſtrange
to
Your Lordſhip, if You had yet ſeen
what
we have heretofore taught in ano­
ther
Treatiſe concerning the Spring that
may
be diſcover'd in Glaſs, as rigid and
inflexible
a Body as it is generally
ſteem
'd.
And in the mean while it may
ſerve
the turn to cauſe a Glaſs Egge to be
blown
exceeding thin, and then, having
broken
it, try how far you can by degrees
bend
ſome narrow parts of it; and how
readily
, upon the removal of what kept
it
bent, it will reſtore it ſelf to its former
ſtate
or poſture.
But to return to our
Experiment
, From thence it ſeems pro­
bable
, either that there ſucceeds no Bo­
dy
in the room of the Air drawn out of
our
Receiver, or that it is not every Mat­
ter
that is ſubtle enough readily to paſs
through
the Pores of Glaſs, that is al­
ways
agitated enough to produce Heat
where
ever it is plentifully found.
So that
if
no Vacuum be to be admitted, this Ex­
periment
ſeems to invite us to allow a
great
diſparity, either as to bulk, or as to
1agitation, or as to both, betwixt ſome
parts
of the Etherial Subſtance, and thoſe
that
are wont here below to produce Heat
and
Fire.
We try'd alſo what Operation the
drawing
out of the Air would have upon
Camphire
, that being a Body, which,
though
not a Liquor, conſiſts of ſuch
Volatile
or Fugitive parts, that without
any
greater agitation then that of the open
Air
it ſelf, they will copiouſly flie away.
But we found not that even this looſe
Body
was ſenſibly alter'd by the Exſucti­
on
of the ambient Air.
IT may ſeem well worth trying, whether

or
no in our exhauſted Glaſs the want
of
an ambient Body, of the wonted thic­
neſs
of Air, would diſable even light and
little
Animals, as Bees, and other winged
Inſects
, to flie.
But though we eaſily
foreſaw
how difficult it would be to make
ſuch
an Experiment; yet not to omit our
endeavors
, we procur'd a large Fleſh-fly,
which
we convey'd into a ſmall Receiver.
We alſo another time ſhut into a great
Receiver
a Humming Bee, that appear'd
ſtrong
and lively, though we had rather
1have made the tryal with a Butter-fly, if
the
cold Seaſon would have permitted us
to
finde any. The Fly, af­
ter
ſome Exſuctions of the
Air
, dropp'd down from the
ſide
of the Glaſs whereon ſhe
was
walking: But, that the
Experiment
with the Bee
might
be the more inſtructive,
we
convey'd in with her a bun­
dle
of Flowers, which re­
main
'd ſuſpended by a ſtring
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
Veſſel
, till at length, as we deſir'd, ſhe
lighted
upon the Flowers; whereupon
we
preſently began to draw out the Air,
and
obſerv'd, That though for ſome time
the
Bee ſeem'd to take no notice of it, yet
within
awhile after ſhe did not flie, but fall
down
from rhe Flowers, without appear­
ing
to make any uſe of her Wings to help
her
ſelf.
But whether this fall of the Bee,
and
the other Inſect, proceeded from the
mediums
being too thin for them to flie in,
or
barely from the weakneſs, and as it were
ſwooning
of the Animals themſelves, you
will
eaſily gather from the following Ex­
periment
.
1
Experi­
ment
40.
TO ſatisfie our ſelves in ſome meaſure,

about
the account upon which Reſpira­
tion
is ſo neceſſary to the Animals, that
Nature
hath furniſh'd with Lungs, we
took
(being then unable to procure any
other
lively Bird, ſmall enough to be put
into
the Receiver) a Lark, one of whoſe
Wings
had been broken by a ſhot, of a
Man
that we had ſent to provide us ſome
Birds
for our Experiment; but notwith­
ſtanding
this hurt, the Lark was very
lively
, and did, being put into the Recei­
ver
, divers times ſpring up in it to a good
height
.
The Veſſel being haſtily, but
carefully
cloſ'd, the Pump was diligently
ply
'd, and the Bird for a while appear'd
lively
enough; but upon a greater Ex­
ſuction
of the Air, ſhe began manifeſtly
to
droop and appear ſick, and very ſoon
after
was taken with as violent and irregu­
lar
Convulſions, as are wont to be ob­
ſerv
'd in Poultry, when their heads are
wrung
off: For the Bird threw her ſelf
over
and over two or three times, and dy­
ed
with her Breaſt upward, her Head
downwards
, and her Neck awry.
And
though
upon the appearing of theſe Con-
1vulſions, we turn'd the Stop-cock, and
let
in the Air upon her, yet it came too
late
; whereupon, caſting our eyes upon
one
of thoſe accurate Dyals that go with
a
Pendulum, and were of late ingeniouſly
invented
by the Noble and Learned Hu­
genius
, 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-ſpar­
row
, which being caught with Bird-lime
was
not at all hurt; when we put her into
the
Receiver, almoſt to the top of which
ſhe
would briskly raiſe her ſelf, the Ex­
periment
being try'd with this Bird, as it
was
with the former, ſhe ſeem'd to be
dead
within ſeven minutes, one of which
were
imploy'd in cementing on the Co­
ver
: But upon the ſpeedy turning of the
Key
, the freſh Air flowing in, began ſlow­
ly
to revive her, ſo that after ſome pant­
ings
ſhe open'd her eyes, and regain'd her
feet
, and in about a 1/4 of an hour, after
threatned
to make an eſcape at the top of
the
Glaſs, which had been unſtopp'd to
let
in the freſh Air upon her: But the Re­
ceiver
being cloſ'd the ſecond time, ſhe
1was kill'd with violent Convulſions,
within
five Minutes from the beginning
of
the Pumping.
Experi­
ment
41.
A while after we put in a Mouſe, new­
ly
taken, in ſuch a Trap as had rather af­
frighted
then hurt him; vvhil'ſt he vvas
leaping
up very high in the Receiver, vve
faſten
'd the Cover to it, expecting that
an
Animal uſed to live in narrow holes
vvith
very little freſh 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 ſet avvork, he conti­
nued
leaping up as before; yet 'tvvas not
long
ere he began to appear ſick and gid­
dy
, and to ſtagger, after vvhich he fell
dovvn
as dead, but vvithout ſuch violent
Convulſions
as the Birds died vvith.
Whereupon, haſtily turning the Key, we
let
in ſome freſh Air upon him, by vvhich
he
recovered, after a vvhile, his ſenſes and
his
feet, but ſeem'd to continue vveak and
ſick
: But at length, grovving able to
skip
as formerly, the Pump vvas plyed
again
for eight minutes, about the mid­
dle
of vvhich ſpace, if not before, a very
little
Air by a miſchance got in at the
Stop-cock
; and about tvvo minutes after
that
, the Mouſe divers times leap'd up
1lively enough, though after about two mi­
nutes
more he fell down quite dead, yet
with
Convulſions far milder then thoſe
wherewith
the two Birds expired.
This
alacrity
ſo little before his death, and his
not
dying ſooner then at the end of the
eighth
minute, ſeem'd aſcribable to the
Air
(how little ſoever) that ſlipt into the
Receiver
.
For the firſt time, thoſe Con­
vulſions
(that, if they had not been ſud­
denly
remedied, had immediately diſ­
patch
'd him) ſeiſ'd on him in ſix minutes
after
the Pump began to be ſet awork.
Theſe Experiments ſeem'd the more
ſtrange
, in regard, that during a great part of
thoſe
few minutes the Engine could but
conſiderably
rarefie the Air (and that too,
but
by degrees) and at the end of them
there
remain'd in the Receiver no incon­
ſiderable
quantity; as may appear by what
we
have formerly ſaid of our not being
able
to draw down Water in a Tube, with­
in
much leſs then a Foot of the bottom:
with
which we likewiſe conſider'd, that by
the
exſuction of the Air and interſper­
ſed
Vapors, there was left in the Recei­
ver
a ſpace ſome hundreds of times ex­
ceeding
the bigneſs of the Animal, to re­
ceive
the fuliginous Steams, from which,
1expiration diſcharges the Lungs; and,
which
in the other caſes hitherto known,
may
be ſuſpected, for want of room, to
ſtifle
thoſe Animals that are cloſely pent
up
in too narrow Receptacles.
I forgot to mention, that having cauſ'd
theſe
three Creatures to be open'd, I
could
, in ſuch ſmall Bodies, diſcover lit­
tle
of what we ſought for, and what we
might
poſſibly 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 uſual enough in the
Lungs
of ſuch winged Creatures, deſerves
not
ſo much our notice, as it does, That
in
almoſt all the deſtructive Experiments
made
in our Engine, the Animals appear'd
to
die with violently Convulſive Moti­
ons
: From which, whether Phyſicians can
gather
any thing towards the Diſcovery
of
the Nature of Convulſive Diſtem­
pers
, I leave to them to conſider.
Having proceeded thus far, though (as
we
have partly intimated already) there
appear
'd not much cauſe 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 ſteams of their Bodies, exquiſite-
1ly pent up in the Glaſs; 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 ſafeſt way to obviate
Objections
, and remove Scruples, by ſhut­
ting
up another Mouſe as cloſe as I could
in
the Receiver, wherein it liv'd above
three
quarters of an hour; and might pro­
bably
have done ſo much longer, had not
a
Virtuoſo of quality, who in the mean
while
chanc'd to make me a Viſit, deſir'd
to
ſee whether or no the Mouſe could be
kill
'd by the exſuction of the ambient Air,
whereupon
we thought fit to open, for a
little
while, an intercourſe betwixt the
Air
in the Receiver, and that without it,
that
the Mouſe might thereby (if it were
needful
for him) be refreſh d, and yet we
did
this without uncementing the Cover
at
the top, that it might not be objected,
that
perhaps the Veſſel was more cloſely
ſtopp
'd for the exſuction of the Air then
before
.
The Experiment had this event, that
after
the Mouſe had liv'd ten Minutes,
(which we aſcrib'd to this, that the Pump,
for
want of having been lately Oyl'd,
could
move but ſlowly, and could not by
1him that manag'd it, be made to work as
nimbly
as it was wont) at the end of that
time
he dy'd with Convulſive Fits, where­
in
he made two or three bounds into the
Air
, before he fell down dead.
Nor was I content with this, but for
Your
Lordſhips further ſatisfaction, and
my
own, I cauſ'd a Mouſe, that was very
hungry
, to be ſhut in all Night, with a
Bed
of Paper for him to reſt upon: And
to
be ſure that the Receiver was well
cloſ
'd, I cauſ'd ſome Air to be drawn out
of
it, whereby, perceiving that there
was
no ſenſible leak, I preſently re-ad­
mitted
the Air at the Stop-cock, leſt the
want
of it ſhould harm the little Animal;
and
then I cauſ'd the Engine to be kept
all
Night by the Fire ſide, to keep him
from
being deſtroy'd by the immoderate
cold
of the Froſty Night.
And this care
ſucceeded
ſo well, that the next Morning
I
found that the Mouſe not onely was
live
, but had devour'd a good part of the
Cheeſe
that had been put in with him.
And
having
thus kept him alive full twelve
hours
, or better, we did, by ſucking out
part
of the Air, bring him to droop, and
to
appear ſwell'd; and by letting in the
Air
again, we ſoon reduc'd him to his for­
mer
livelineſs.
1
A Digreſsion containing ſome
Doubts
touching Reſpi­
ration
.
I Fear Your Lordſhip will now expect,
that
to theſe Experiments I ſhould add
my
Reflections on them, and attempt,
by
their aſſiſtance, to reſolve the Diffi­
culties
that occur about Reſpiration; ſince
at
the beginning I acknowledg'd a further
Enquiry
into the Nature of that, to have
been
my Deſign in the related Tryals.
But I have yet, becauſe of the inconve­
nient
Seaſon of the Year, made ſo few
Experiments
, and have been ſo little ſa­
tisfied
by thoſe I have been able to make,
that
they have hitherto made Reſpiration
appear
to me rather a more, then a leſs
Myſterious
thing, then it did before.
But
yet
, ſince they have furniſh'd me with
ſome
ſuch new Conſiderations, concern­
ing
the uſe 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 ſullen or lazy, I
am
content not to decline employing a
1few hours in ſetting down my Doubts, in
preſenting
Your Lordſhip ſome Hints,
and
in conſidering whether the Tryals
made
in our Engine, will at leaſt aſſiſt us
to
diſcover wherein the Deficiency lies
that
needs to be ſupply'd.
And this, My Lord, being all my pre­
ſent
Deſign, I ſuppoſe You will not ex­
pect
that (as if You knew not, or had for­
gotten
what Anatomiſts are wont to
teach
) I ſhould entertain You with a need­
leſs
Diſcourſe of the Organs of Reſpira­
tion
, and the variety of their Structure in
ſeveral
Animals; though if it were ne­
ceſſary
, and had not been perform'd by
thers
, I ſhould think, with Galen, that by

treating
of the Fabricks of living Bodies,
I
might compoſe Hymns to the wiſe Au­
thor
of Nature, who, in the excellent con­
trivance
of the Lungs, and other parts of
(thoſe admirable Engines) Animals, ma­
nifeſts
himſelf to be indeed what the Elo­
quent
Prophet moſt juſtly ſpeaks him,
Wonderful in Counsel, and excellent in

working.
Galenus de
, Part:
lib
. 3.
a.28.29.
Nor ſhall we any further meddle with
thoſe
Controverſies ſo much agitated
mong
the Moderns, namely, Whether the
motion
of the Lungs in Reſpiration be their
1own, or but conſequent to the motion of the
Thorax
, Diaphragme, and (as ſome Learn­
ed
Men would have it) the Abdomen; And,
Whence
it is that the Air ſwells the Lungs
in
Inſpiration any further then they may
receive
light from our Engine: But that
it
may appear what kinde of ſervice it is
that
may be expected from it on this oc­
caſion
, we muſt premiſe a few Words to
ſhew
wherein the ſtrength of the Obje­
ction
we are to anſwer, lies.
In favor then
of
thoſe that would have the Lungs ra­
ther
paſſive then active in the buſineſs of
Reſpiration
, it may againſt the common
opinion
be alledg'd, That as the Lungs be­
ing
deſtitute of Muſcles and of Fibres,
are
unfit to dilate themſelves; ſo it ap­
pears
, that without the motion of the
Thorax they would not be fill'd with Air.
Since as our Learned Friend Dr. High­
more
has well (and congruouſly, to what
our
ſelves have purpoſely try'd) ob­
ſerv
'd, if a live Dog have a great wound
made
in his Cheſt, the Lobes of the
Lungs
on that ſide of the Mediaſti­
num
will ſubſide and lie ſtill; the Tho­
rax
and the Lobes on the other ſide
of
the Mediaſtinum, continuing their
former
motion.
And if ſuddenly at once
1the Muſcles of the Cheſt be on both
ſides
diſſected, upon the Ingreſs of the
Air
, the whole Lungs, though untouch'd,
will
remain moveleſs, at leaſt, as to any ex­
panſion
or contraction of their ſubſtance.
To which we may adde the Obſervati­
on
of the diligent Bartholinus, who af­
firms
the like of the Diaphragme al­
ſo
, namely, That it being wounded, the
Lungs
will fall together, and the Reſpi­
ration
ceaſe, which my Experiments op­
poſe
not, provided the Wound be any
thing
great.
And indeed the Diaphragme
ſeems
the principal Inſtrument of ordina­
ry
and gentle Reſpiration, although to
reſtrain
'd Reſpiration (if I may ſo call
it
) the intercoſtal Muſcles, and perhaps
ſome
others may be allowed eminently to
concur
.
But the chief of the Contro­
verſies
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, thoſe
that
plead for the Lungs, demand what it
is
that ſhould bring the Air into the
Lungs
, if themſelves do not attract it,
their
Antagoniſts diſagree about the Re­
ply
.
For when to this queſtion ſome of
the
beſt Modern Philoſophers anſwer,
1that by the dilatation of the Cheſt the
contiguous
Air is thruſt away, and that
preſſing
upon the next Air to it, and ſo
onwards
, the Propulſion is continued till
the
Air be driven into the Lungs, and ſo
dilate
them: When this (I ſay) is an­
ſwered
, it is Objected even by Bartholine
himſelf
, as a convincing Reply, that, ac­
cording
to this Doctrine, a Man could not
fetch
his Breath from a great Veſſel full of
Air
, with a ſlender Neck, becauſe, that
when
his Mouth covers the Orifice of the
Neck
, the dilatation of his Thorax could
not
propell the Air in the Veſſel into his
Lungs
, by reaſon of its being ſeparated
by
the incloſing Veſſel from the ambient
Air
; and yet, ſay they, Experience wit­
neſſes
that out of ſuch a Veſſel a Man may
ſuck
Air.
But of this difficulty our Engine
furniſhes
us with an eaſie Solution, ſince
many
of the former Experiments have ma­
nifeſted
, That in the caſe propoſed, there
needs
not be made any (though 'tis true
that
in ordinary Reſpiration there is wont
to
be made ſome) propulſion of the Air by
the
ſwelling Thorax or Abdomen into the
Lungs
; ſince upon the bare Dilatation of
the
Thorax, the Spring of that internal
Air
, or halituous ſubſtance that is wont
1to poſſeſs as much of the Cavity of the
Cheſt
as the Lungs fill not up, being much
weaken
'd, the external and contiguous
Air
muſt neceſſarily preſs in at the open
Winde-Pipe
into the Lungs, as finding
there
leſs reſiſtance then any where elſe
bout
it.
And hence (by the way) we may derive
a
new aſſiſtance to judge of that famous
Controverſie
diſputed among Naturaliſts
and
Phyſitians, ever ſince Galens time,
ſome
maintaining that the Cheſt, with the
contained
Lungs, may be reſembled to a
pair
of Bellows, which comes therefore
to
be fill'd becauſe it was dilated: And
thers
pleading to have the compariſon
made
to a Bladder, which is therefore di­
lated
becauſe it is fill'd.
For as to the
Thorax, it ſeems evident from what has
been
lately ſaid, that it, like a pair of Bel­
lows
, happens to be partly fill'd with Air,
but
becauſe it was dilated: But as for the
Lungs
themſelves, who want Fibres to
diſtend
them, they may fitly enough be
compar
'd to a Bladder; ſince they are di­
lated
by being fill'd, namely, by that Air
which
ruſhes into them upon the dilatation
of
the Cheſt, in whoſe increaſed Cavity
it
findes (as we freſhly noted) leſs reſiſt-
1ance to its Spring then elſewhere. And
this
brings into my minde that ſtrange
Obſervation
of Nicolaus Fontanus, a Phy­

ſitian
at Amſterdam, who teſtifies, That
in
a Boy of the ſame Town, four years
old
, there was found, inſtead of Lungs, a
certain
Membranous Bladder; which be­
ing
fill'd with Wind, and furniſh'd with
little
Veins, had its origination from the
Wind-Pipe
it ſelf; which being ſuppoſ'd
true
, how well it will agree with moſt of
the
Opinions touching Reſpiration, I leave
to
be conſidered.
Fontanus >
apud
Bar­
tholin
: lib.
2
. cap. 9.
And thus may the grand Objection of
Bartholine, and others, be anſwered: But
I
leave to Anatomiſts to conſider what is
to
be ſaid to ſome Obſervations that ſeem
to
contradict thoſe Anatomical Experi­
ments
already mention'd: Such was par­
ticularly
that which I remember I have
read
in Sennertus (from the obſervation of
his
Father-in-law Schato) of a Melancho­
ly
Student, who having ſtabb'd himſelf,
and
pierced the Diaphragme in the thinner
or
tendonous part (call'd by many the
Nervous
Circle) lived ſeven Moneths af­
ter
he had ſo wounded himſelf, though af­
ter
his death (preceded by violent Vomit-
1ings) the Wound (perchance dilated by
thoſe
ſtrainings) appear'd ſo great, that
the
whole Stomack was found to have got
in
by it into the left ſide of the Thorax.
And
ſuch alſo was the accident that hap­
pen
'd to a Noble Man, whom I remem­
ber
I have ſeen, and who is yet alive, in
whoſe
Cheſt there has, for theſe many
years
, remain'd a hole ſo great, that the
motion
of his Heart may be perceiv'd by
it
.
Theſe (I ſay) and ſome other Obſer­
vations
, I ſhall now forbear to inſiſt on,
becauſe
I hold it not unfit, before we
come
to conſider the uſe of Reſpiration,
that
we acquaint Your Lordſhip with an
Ingenious
Conjecture, that was made at
the
cauſe of the haſty death of the Ani­
mals
our Engine kill'd: namely, That it
was
not the want of Air that deſtroy'd
them
, but the Preſſure of the innate Air
in
the cavity of the Cheſt; as if the
Spring
of this Air being no longer coun­
terballanc
'd by the ambient Air, was there­
by
become ſo ſtrong, that it kept the
Thorax forcibly diſtended, and hinder'd its
wonted
contraction; and ſo compreſſ'd
the
Lungs and their Veſſels, as to obſtruct
the
Circulation of the Blood.
And this
1Conjecture, as it is ſpecious enough, ſo I
might
have admitted it for true; but that
I
conſider'd, that (not to mention that
one
, eſpecially of the Animals kill'd in
our
Engine, ſeem'd manifeſtly for a pret­
ty
while, and not long before he dy'd, to
move
his Thorax, as if he exerciſ'd Reſpi­
ration
) the diligent Wallæus relates, That
he
divers times obſerv'd, in the Diſſecti­
on
of live Bodies, that the Membrane
that
inveſts the Lungs, had Pores in it
as
big as the larger ſort of Peas, which
grees
with the Obſervations of Chyrur­
gions
and Phyſitians, viz. That matter
collected
in the Thorax, has penetrated in­
to
the Lungs, and been diſcharged by
coughing
.
And I remember too, that moſt
of
the Animals we kill'd in our Engine
were
Birds, of whoſe Lungs Harvey
ſomewhere
informs us, That he ob­
ſerv
'd them very manifeſtly to open at
their
Extremities into the Abdomen.
And
by ſuch Perforations we may well
ſuppoſe
the paſſage free betwixt the exter­
nal
Air and that in the Abdomen: But this
Conjecture
may be further conſider'd.
Beſides, to ſhow that the Animals that
died
in our Glaſſes, need not be ſuppoſ'd
1to have been kill'd by the want of Air, we
foreſee
another Argument that we muſt
deal
ſo ingeniouſly with Your Lordſhip,
as
not to conceal.
You very well know,
that
beſides the generality of the
Schools
, there are many new Philoſophers
who
, though they diſſent from the old
Peripateticks
in other things, do, as they,
deny
the poſſibility of a Vacuum; and
hold
, that thoſe ſpaces which are devoid
of
Air, and other groſſer Bodies, are all
of
them exactly repleniſhed with a certain
Etherial
Matter, ſo thin and ſubtle, that
it
can freely permeate the Pores of the
compactedſt
and cloſeſt Bodies, and ev'n
of
Glaſs it ſelf.
Now ſome of thoſe Na­
turaliſts
that are of this perſwaſion may
object
, That the Animals that died in our
Receivers
, did ſo, not ſo much for lack of
Air
, as by reaſon that the Air that was
pump
'd out was neceſſarily ſucceeded by
an
Etherial Subſtance; which conſiſting of
parts
vehemently agitated, and ſo very
ſmall
, as without reſiſtance to paſs in and
out
through the very Pores of Glaſs; it
may
well be ſuppoſ'd, that a conſiderable
quantity
of this reſtleſs and ſubtle Mat­
ter
, meeting together in the Receiver,
1with the exceſſive heat of it, may be
quickly
able to deſtroy a little Animal, or
at
leaſt, make the Air too intemperately
hot
to be fit for Reſpiration.
But though this be a Difficulty not ſo
eaſily
to be reſolv'd without the aſſiſtance
of
our Engine, yet I ſuppoſe we have al­
ready
anſwer'd the Objection by our 38th
and
39th Experiments; which though we
made
partly for other purpoſes, yet we
premiſ
'd them onely to clear up the diffi­
culty
propoſ'd.
Another ſuſpition we ſhould have en­
tertain
'd concerning the death of our Ani­
mals
, namely, That upon the ſudden re­
moval
of the wonted preſſure of the am­
bient
Air, the warm Blood of thoſe Ani­
mals
was brought to an Efferveſcence or
Ebullition
, or at leaſt ſo vehemently ex­
panded
, as to diſturb the Circulation of
the
Blood, and ſo diſorder the whole Oe­
conomy
of the Body. (This (I ſay) I
ſhould
have had ſome ſuſpition of) but
that
Animals of a hot Conſtitution are
not
the ſole ones that cannot in our ex­
hauſted
Engine exerciſe the Function of
Life
.
But I muſt not now dwell upon
matters
of this nature, becauſe I think
it
high time to proceed to the conſiderati-
1on of the principal ſubject of our Engine,
namely
, The uſe of Reſpiration; or ra­
ther
, The uſe of the Air in Reſpiration.
For whereas of the divers uſes of it men­
tion
'd by Anatomiſts the moſt, ſuch as
the
Production and Modulation of the
Voice
by the Eliſion of the Air, the La­
rynx
&c.
the expulſion of Excrements
by
Coughing, the conveying in of Odours
by
Inſpiration, and ſome others, rather
convenient
for the well being of an Ani­
mal
, then abſolutely neceſſary to his Life:
Whereas
(I ſay) the other uſes are ſuch as
we
have ſaid, The great Hippocrates him­
ſelf
gives this notable Teſtimony to the
uſe
of the Air, as to Animals endow'd
with
Lungs, Mortalibus (ſays he) hic (ſpi­
ritus
) tum vitæ, tum morborum ægrotis cau­
ſa
eſt.
Tantáque corporibus omnibus ſpi­
ritûs
ineſt neceßitas, ut ſiquidem aliis om­
nibus
& cibis & potionibus, quis abſtineat,
duos
tamen aut tres, vel plures dies poßit vi­
tam
ducere: At ſi quis ſpiritus in corpus
vias
intercipiat, vel exiguâ diei parte, ho­
mini
pereundum ſit; Adeo neceſſarius eſt
uſus
ſpiritûs in corpore.
Ad hæc quo〈qué〉,
quum
omnibus aliis actionibus homines qui­
eſcant
, quod mutationibus innumer is vita
ſit
expoſita, ab hâc tamen ſolâ actione nun-
1quam deſiſtant animantia, quin aut ſpiritum
adducant
, aut reddant.
But touching the account upon which
the
Inſpiration and Exſpiration of Air
(both which are comprehended in ἀγαπνο,
Reſpiration
) is ſo neceſſary to Life, both
Naturaliſts
and Phyſitians do ſo diſagree,
that
it will be very difficult either to re­
concile
their Opinions, or determine their
Controverſies
.
For firſt, Many there are who think
the
chief (if not ſole) uſe of Reſpiration
to
be the Cooling and tempering of that
Heat
in the Heart and Blood, which other­
wiſe
would be immoderate: And this
pinion
, not onely ſeems to be moſt recei­
ved
amongſt Scholaſtick Writers, but di­
vers
of the new Philoſophers, Carteſians,
and
others, admitted with ſome variation;
teaching
, That the Air is neceſſary, by its
coldneſs
, to condenſe the Blood that paſ­
ſes
out of the right Ventricle of the
Heart
into the Lungs, that thereby it may
obtain
ſuch a conſiſtence, as is requiſite
to
make it fit Fewel for the vital Fire or
Flame
, in the left Ventricle of the heart.
And this Opinion ſeems favor'd by this,
That
Fiſhes, and other cold Creatures,
whoſe
Hearts have but one cavity, are al-
1ſo unprovided of Lungs, and by ſome
ther
conſiderations.
But though it need
not
be deny'd, that the inſpir'd Air may
ſometimes
be of uſe by refrigerating the
Heart
; yet (againſt the Opinion that makes
this
Refrigeration, the moſt genuine and
conſtant
uſe of the Air) it may be Obje­
cted
, That divers cold Creatures (ſome
of
which, as particularly Frogs, live in
the
Water) have yet need of Reſpiration,
which
ſeems not likely to be needed for
Refrigeration
by them that are deſtitute of
any
ſenſible heat, and beſides, live in the
cold
Water: That even decrepid old
Men
, whoſe natural heat is made very
languid
, and almoſt extinguiſh'd by rea­
ſon
of age, have yet a neceſſity of fre­
quent
Reſpiration: That a temperate Air
is
fitteſt for the generality of breathing
Creatures
; and as an Air too hot, ſo al­
ſo
an Air too cold, may be inconvenient
for
them (eſpecially, if they be troubled
with
an immoderate degree of the ſame
Quality
which is predominant in the Air:)
That
in ſome Diſeaſes the natural heat is
ſo
weaken'd, that in caſe the uſe of Reſpi­
ration
were to cool, it would be more
hurtful
then beneficial to breath; and the
ſuſpending
of the Reſpiration, may ſup-
1ply the place of thoſe very hot Medicines
that
are wont to be employ'd in ſuch Di­
ſtempers
: That Nature might much bet­
ter
have given the Heart but a moderate
heat
, then ſuch an exceſſive one, as needs
to
be perpetually cool'd, to keep it from
growing
deſtructive; which the gentle,
and
not the burning heat of an Animals
Heart
, ſeems not intenſe enough ſo indi­
ſpenſably
to require.
Theſe, and other
Objections
, might be oppoſ'd, and preſſ'd
againſt
the recited Opinion: But we ſhall
not
inſiſt on them, but onely adde to
them
, That it appears not by our fore­
going
Experiments (I mean the 38th and
39
th) that in our exhauſted Receiver,
where
yet Animals die ſo ſuddenly for
want
of Reſpiration, the ambient Body is
ſenſibly
hotter then the common Air.
Other Learned Men there are, who will
have
the very ſubſtance of the Air to get
in
by the Veſſels 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 theſe alledge
for
themſelves the Authority of the An­
tients
, among whom Hippocrates ſeems
manifeſtly
to favor their Opinion; and
both
Ariſtotle and Galen do ſometimes
1(for methinks they ſpeak doubtfully
nough
) appear inclinable to it.
But for
ought
ever I could ſee in Diſſections, it is
very
difficult to make out, how the Air is
convey
'd into the left Ventricle of the
Heart
, eſpecially the Syſtole and Diaſtole
of
the Heart and Lungs, being very far
from
being Synchronical: Beſides, that
the
Spirits ſeeming to be but the moſt
ſubtle
and unctuous Particles of the
Blood
, appear to be of a very differing
Nature
from that of the lean and incom­
buſtible
Corpuſcles of Air.
Other Ob­
jections
againſt this Opinion have been
propoſ
'd, and preſt by that excellent Ana­
tomiſt
, and my Induſtrious Friend, Dr.
Highmore, to whom I ſhall therefore refer
you
.
Another Opinion there is touching Re­
ſpiration
, which makes the genuine uſe of
it
to be Ventilation (not of the Heart,
but
) of the Blood, in its paſſage thorow
the
Lungs; in which paſſage, it is diſ­
burthened
of thoſe Excrementitious
Steams
, proceeding, for the moſt part,
from
the ſuperfluous Seroſities of the
Blood
, (we may adde) and of the Chyle
too
, which (by thoſe new Conduits of
late
very happily detected by the famous
1Pecquet) hath been newly mix'd with it in
the
Heart.) And this Opinion is that of
the
Induſtrious Mœbius, and is ſaid to
have
been that of that excellent Philoſo­
pher
Gaſſendus; and hath been in part an
Opinion
almoſt vulgar: But this Hypo­
theſis
may be explicated two ways: For
firſt
, The neceſſity of the Air in Reſpi­
ration
, may be ſuppoſ'd to proceed from
hence
; That as a Flame cannot long burn
in
a narrow and cloſe place, becauſe the
Fuliginous
Steams it unceſſantly 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, ſti­
fles
the flame, ſo that the vital Fire in the
Heart
requires an ambient Body, of a
yielding
nature, to receive into it the ſu­
perfluous
Seroſities and other Recrements
of
the Blood, whoſe ſeaſonable Expulſi­
on
is requiſite to depurate the Maſs of
Blood
, and make it fit both to Circulate;
and
to maintain the vital heat reſiding in
the
Heart.
The other way of explicating
the
above-mention'd Hypotheſis, is, by
ſuppoſing
, 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,
1but does alſo convey them out of the
Lungs
, in regard that the inſpired Air,
reaching
to all the ends of the Aſpera Ar­
teria
, does there aſſociate it ſelf with the
Exhalations
of the circulating Blood, and
when
tis exploded, carrys them away with
it
ſelf, as we ſee that winds ſpeedily dry up
the
ſurfaces of wet Bodies, not to ſay any
thing
of what we formerly obſervd touch­
ing
our Liquor, whoſe fumes were ſtrange­
ly
elevated upon the Ingreſs of the Air.
Now of theſe two ways of explicating
the
uſe of Reſpiration, our Engine af­
fords
us this Objection againſt the firſt;
That
upon the Exſuction of the Air, the
Animals
die a great deal ſooner then if it
were
left in the Veſſel; though by that
Exſuction
the ambient ſpace is left much
more
free to receive the ſteams that are ei­
ther
breathed out of the Lungs of the
Animal
, or diſcharg'd by inſenſible Tran­
ſpiration
through the Pores of his
Skin
.
But if the Hypotheſis propoſ'd, be taken
in
the other ſenſe, it ſeems congruous
nough
to that grand obſervation, which
partly
the Phænomena of our Engine, and
partly
the relations of Travellers, have
ſuggeſted
to us, namely, That there is a
1certain conſiſtence of Air requiſite to Re­
ſpiration
; ſo that if it be too thick, and
already
over-charged with vapors, it will
be
unfit to unite with, and carry off thoſe
of
the Blood, as Water will diſſolve, and
aſſociate
to it ſelf but a certain proportion
of
ſaline Corpuſcles; and if it be too
thin
or rarefied, the number or ſize of the
Aërial
Particles is too ſmall to be able to
aſſume
and carry off the halituous Excre­
ments
of the Blood, in ſuch plenty as is
requiſite
.
Now that Air too much thicken'd (and
as
it were clogg'd) with Steams, is unfit
for
Reſpiration, may appear by what is
wont
to happen in the Lead-Mines of De­
vonſhire
, (and, for ought I know, in thoſe
too
of other Countrys, though I have
ſeen
Mines where no ſuch thing was com­
plain
'd of) for I have been inform'd by
more
then one credible Perſon (and parti­
cularly
by an Ingenious Man, that has of­
ten
, for curioſity, digg'd in thoſe Mines,
and
been imploy'd about them) that there
often
riſes Damps, as retaining the Ger­
mane
Word by which they call them)
which
does ſo thicken the Air, that unleſs
the
Work-men ſpeedily make ſigns to
them
that are above, they would (which
1alſo ſometimes happens) be preſently
ſtifled
for want of Breath; and though
their
Companions do make haſte to draw
them
up, yet frequently, by that time
they
come to the free Air, they are, as it
were
, in a ſwoon, and are a good while be­
fore
they come to themſelves again.
And
that
this ſwooning ſeems not to proceed
from
any Arſenical or Poyſonous Exhala­
tion
contain'd in the Damp, as from its
over-much
condenſing the Air, ſeems pro­
bable
from hence; That the ſame Damps
oftentimes
leiſurely extinguiſh the flames
of
their Candles or Lamps; and from
hence
alſo that it appears (by many Rela­
tions
of Authentical Authors) that in
thoſe
Cellars where great ſtore of new
Wine
is ſet to work, men have been ſuffo­
cated
by the too great plenty of the ſteams
exhaling
from the Muſt, and too much
thickning
the Air: as may be gathered
from
the cuſtom that is now uſed in ſome
hot
Countrys, where thoſe that have oc­
caſion
to go into ſuch Cellars, carry with
them
a quantity of well kindled Coals,
which
they hold near their Faces; where­
by
it comes to paſs, that the Fire diſcuſ­
ſing
the Fumes, and rarefying the Air re­
duces
the ambient Body to a conſiſtence fit
for
Reſpiration.
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