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Chambers, Ephraim, 1680 (ca.)-1740 / Cyclopædia, or, An universal dictionary of arts and sciences : containing the definitions of the terms, and accounts of the things signify'd thereby, in the several arts, both liberal and mechanical, and the several sciences, human and divine : the figures, kinds, properties, productions, preparations, and uses, of things natural and artificial : the rise, progress, and state of things ecclesiastical, civil, military, and commercial : with the several systems, sects, opinions, &c : among philosophers, divines, mathematicians, physicians, antiquaries, criticks, &c : the whole intended as a course of antient and modern learning
(1728)

U[/V] - venter,   pp. 273-292 PDF (20.2 MB)


Page 274


VAC                           [27
k6n-retum'ing Curve; becaufe in either of ihofe Cafes, the
Protrufion, and confequently the Refiflance, would be infinite;
There remains, therefore, only the Motion in a revolving
Curve prafficable; which muit either be a Revolution upon
an Axis, or an annular Motion round a quiefcent Bodyi
both which are, again, impoflible in an Elliptic Curve:
And contequently, all Motion muft be in Circles geometri-
cally true; and the revolving Bodies mufl either be Spheres,
Spheroids; Cylinders, or Portions of them, exacfly geome-
trical; otherwife, their Revolutions in a Plenum would be
impoffible: But fuch Motions, or fuch figur'd Bodies, we do
niot khow in Nature. Therefore there is a Vacuum.
2Y. The Motions of the Planets and Comets demonfirate
a Vacuum: Thus Sir L Newt* argues; ' That there is no
X fuch fluid Medium as AEther, (to fill up the porous Parts
of all fenfible Bodies, as the Air and interfiellar Parts,
and fo make a Plenum) ' feems probable; becaufe the Pla-
' nets and Comets proceed with fo regular and laffing a
' Motion thro' the Celefiial Spaces, both from and to all
' Parts: For hence it appears, that thofe Celeffial Spaces
' are void of all fenfible Refiflance, and confequently of
' all fenfible Matter. For the refining Force of fluid Me-
' diums, arifes partly from the Attrition of the Parts of the
' Medium, and partly from the Inacfivity of Matter. Now
' that Part of the Refiflance of any Medium, which arifes
' from the Tenacity or Attrition of its Parts, may be lefen'd
£ by dividing the Matter into fmaller Parts, and by rendring
thofe Parts more fmooth and flippery: But that Part of
' the Refiflance which arifes from the Inactivity of Matter,
is always in proportion to the Denfity of the Matter; nor
can be diminifh d by dividing the Matter, nor by any other
' means, except by diminifhing the Denfity thereof.
' Confequently, if the Celefial Regions were as denfe as
Water, or Quickfilver, they would refill almofl as much
£ as Water or Quickfilver; but if they were perfealy denfe,
' without any interffers'd Vacuity, tho the Matter were
ever fo fluid and fubtile, they would refill more than
' Quickfilver does; a perfealy folid Globe, in fuch a Me-
' dium, would lofe above half its Motion, in moving three
Lengths of its Diameter; and a Globe not perfeckly folid,
' fuch as the Bodies of the Planets and Comets are, would
' be flop'd fill fooner. Therefore, that the Motion of the
Planets and Comets may be regular and lafling, it is ne-
'celary the Celeflial Spaces be void of all Matter, except
perhaps fome few and much rarified Effluvia of the Pla-
' nets and Comets, and the paffing Rays of Light. See
REsIsTANCE, MEDIUM, PLANET, COMET, &C.
O*. The fame great Author deduces a Vacuum from the
Confideration of the Weights of JBodies; thus: ' All Bo-
' dies about the Earth gravitate towards the Earth; and
the Weights of all Bodies equally dillant from the Earth's
' Centre, are as the Quantities of Matter in thofe Bodies.
-If the .Ether, therefore, or any other fubtile Matter,
were altogether deflitute of Gravity, or did gravitate lefs
' than in proportion to the Quantity of its Matter: Becaufe,
(as arifiotle, fDes Cartes, and others argue) it differs from
other Bodies only in the Form of the Matter; the fame
Body might by the Change of its Form gradually be con-
' verted into a Body of the fame Conflitution with thofe
which gravitate moll in proportion to the Quantity of
£ Matter: and on the other hand, the moft heavy Bodies
might gradually lore their Gravity, by gradually chang-
' ing their Form; and therefore the Weights would depend
' upon the Forms of Bodies, and might be chang'd with
' 'em; which is contrary to all Experiment. See WEIGHT.
40. The Defcent of Bodies proves that all Space is not
equally full; for the fame Author goes on, ' If all Spaces
' were equally full, the Specifick Gravity of that Fluid with
' which the Region of the Air would in that Cafe be fill'd,
' would not be lefs than the Specific Gravity of Quickfil-
' ver, or Gold, or any other the moil denfe Body; and
therefore, neither Gold, nor any other Body, could defcend
' therein. For Bodies do not defcend in a Fluid, un-
' lefs that Fluid be Specifically lighter than the Body. But
' by the Air-Pump, we can exhaufl a Veashl, till even a
Feather Shall fall with a Velocity equal to that of Gold
in the open Air: The Medium, therefore, thro' which the
' Feather falls, mulf be much rarer than that thro' which
' the Gold falls.' See DESCENT.
The Quantity of Matter, therefore, in a given Space,
may be diminifh'd by Rarefaffion: and why may not it
be diminifh'd in infinitum ? Add, that we conceive the
folid Particles of all Bodies to be of the fame Denfity -
' and that they are only rarefiable by means of their Pores :
Whence a Vacuum evidently follows.' SeeRAREFACTION,
PORES, and PARTICLE.
5D0 I That there is a Vacuum, is evident from the Vi-
brations of Pendulums: For fince thofe Bodies, in Places
* out of which the Air is exhaufled, meet with no Refif-
tance to retard their Motion, or fhorten their Vibrations;
U tis evident there is no fenfible Matter in thofe Spaces, or
' in the occult Pores of thofe Bodies. See PENDULUM.
]                        V A C
For, as to what yes Cartes urges of his Materia Subtilisj
ibhat its Tenuity prevents its Refiflance from being fenfible,
and that a fmall Body firiking againfi a greater, cannot in
the leaf move, or refill the Motion of that other ; but is refleat-
ed back again with all its Momentum: 'tis contrary to all
Experience. For Sir Ifaac provesi that the Denfity of fluid
Mediums, is proportionable to their Refiflances very nearly;
and that they are exceedingly miflaken, who fuppofe the
Refillance of Projeffiles to be infinitely diminifhfcd, by di-
viding the Parts of the Fluid, even in infinitum. (PrincCiP
Lib. II. Prop. 38.) When, on the contrary, 'tis clear the
Refillance is but little diminifh'd by the Subdivifion of the
Parts; (Ibid. Prop. 40.) and that the refining Forces of all
Fluids are nearly as their Denfities. For why fhould not
the fame quantity of Matter, whether divided into a great
number oAfubtile Parts, or into a few larger ones, have the
fame refilling Force ?  If then there were no Vacuum, it
would follow, that a Projeffile moving in the Air, or even
in a Space whence the Air is exhaulled, fhould move with
as much difficulty as in Quickfilver; which is contrary to
Experience. See PROJECTILE.
60. That there are Interfers'd Vacuities, appears from
Matter's being atlually divided into Parts, and from the Fi-
gures of thofe Parts: For, on Suppofition of an abfolute
Plenitude, we do not conceive how any Part of Matter could
be aaually divided from that next adjoining, any more than
it is poffible to divide actually the Parts of abfolute Space
from one another: for by the aaiual Divifion of the Parts
of a Continuumn from one another, we conceive nothing elfe
underilood, but the placing thofe Parts at diflances from one
another which in the Continuum were at no distance from one
another: But fuch Divifions between the Parts of Matter$
mufl imply Vacuities between. See DIvisIBiLITY.
70. As for the Figures of the Parts of Bodies, upon the
Suppofition of a Plenum, they mufl either be all Reffi-
linear, or all Concavo-convex; otherwise, they would not ade-
quately fill Space; which we do not find to be true in Facft.
8f. The denying a Vacuum fuppofes what it is impoffible
for any one to prove to be true, viz. That the material
World hath no Limits. See UNIVERSE.
Since, then the Effence of Matter does not confifl in Ex-
tenfion, but in Solidity, or Impenetrability, the Univerfe
may be faid to confife of folid Bodies moving in a Vacuum:
Nor need we at all fear, lea the Phenomena of Nature,
moil of which are plaufibly accounted for from a Plenitude,
fhould become inexplicable when the Plenum is fet afide.
The principal ones, fuch as the Tides; the Sufpenfion of
the Mercury in the Barometer; the Motion of the Hea-
venly Bodies, of Light, sic. are more eafily and fatisfadto.
rily accounted for from other Principles. See TIDES, UC.
VACUUM, or VACUUM Boyleanum, is alfo ufed, fome-
what abufively, to exprefs that approach to a real Vacuum,
which we arrive at by means of the Air-Pump. See AIR-
Pump.
Thus, any thing put in a Receiver fo exhaulled, is faid
to be put in Vacuo: and thus, moft of the Experiments
with the Air-Pump, are perform'd in Vacuo, or in Vacua
!Boyleano.
Some of the principal Phb'nomena obferv'd of Bodies is
Vacuo, are; That the heaviel and lighteft Bodies, as a
Guinea and a Feather, fall here with equal Velocity:-
That Fruits, as Grapes, Cherries, Peaches, Apples, Fec.
kept for any time in Vacuo, retain their Nature, Frethnefs,
Colour, Eec. and thofe wither'd in the open Air, recover
their Plumpnefs in Vacuo:-All Light and Fire becomes
immediately extin6t in Vacuo :-The Collifion of Flint and
Steel in Vacuo, produces no Sparks :-No Sound is heard,
even from a Bell rung in Vacuo -A   fquare Viol, HIll of
common Air, well clos'd, breaks in Vacuo; a round one
does not :-A Bladder half full of Air, will heave up 40
Pound weight in Vacuo :-Cats, and moil other Animals,
readily expire in Vacuo.
By Experiments made in 1704, Mr. Derham found, that
Animals which have two Ventricles, and no Foramen Ovale,
as Birds, Dogs, Cats, Mice, &c. die in lefs than half a
Minute; counting from the firfi Exfuction: A Mole died in
one Minute ; a Bat liv'd feven or eight. Infeas, as Wafps,
Bees, Gra fhoppers, &c. feem'd dead in two Minutes; bur,
being left in Vacuo 24 Hours, came to life again in the
open Air: Snails continu'd 24 Hours in Vacuo, without ap-
pearing much concern'd.
Seeds planted in Vacuo don't grow :-Small Beer dies,
and lofes all its Talle in VacUo:-Lukewarm Water boils
very vehemently in Vacuo :-Air, rufhing thro' Mercury in.
to a Vacuum, throws the Mercury in a kind of Shower upon
the Receiver, and produces a great Light in a dark Room.
See ATTRITION, tC.
The Air-Pump can never produce a precife Vacuum; as is
evident from its Structure, and the manner of its working:
In efle, every Exfufion only takes out a part of the Air:
fo that there will flill be fome left, after any finite Number
of Exfufions. Add, that the Air-Pump has no longer any


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