Page:Cyclopaedia, Chambers - Volume 2.djvu/987

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VOR

way, and that the Inteftines are prefs'd by the Diaphragm, and the Mufcles of the lower Venter.

The primary Caufe of Vomiting, ufes to be the too great Quantity, or too much Acrimony of the Contents, arifing from Poifons, Contufions, Compreffions, Inflammations, and Wounds in the Brain, Inflammations of the Diaphragm, Sto- mach, Inteftines, Spleen, Liver, Kidneys, Panchreas, and Mefentery; unufual Agitations in Coaches, at Sea, £S?c. and vomitive or emetic Medicines. See Emetics.

VOMITIVE, or Vomiting Medicines. See Emetics. VOPISCUS, a Latin Term, ufed in refpect of Twins in the Womb, for that which comes to the perfect Birth. See Twins.

VORTEX, Whirkmnd, in Meteorology, a fudden, rapid, violent Motion of theAir,in Gyres or Circles. SeeWn ir lwind. Vortex, Vorago, is alfo ufed for an Eddey, or Whirl- pool • or a Body of Water in certain Seas and Rivers, which runs rapidly around, forming a fort of Cavity in the middle. The ordinary Caufe of thefe Vortices, is a Gulph, or Out- let, whereby the Water of the Sea, ££fc. is abforbed, or pre- cipitates itfelf into fome other Receptacle; fometimes to fome other communicant Sea, and fometimes, perhaps, into the vaft Abyfs of central Water. See Whirlpool, and Abyss.

An artificial Vortex, expreffive of the Phenomena of the natural ones, may be made with a cylindric Veffel, placed, immoveable, on a horizontal Plane, and fill'd to a certain height with Water. — In this Water a Stick being plunged, and turn'd round as brifkly as may be, the Water is neceffa- rily put into a pretty rapid circular Motion, and rifes to the very Edge of the Veffel, and when there arrived, ceafes to be further agitated.

The Water thus rais'd forms a Cavity in the Middle, whofe Figure is that of a truncated Cone; its Bafe is the fame with the upper Cavity of the Veffel, and its Vertex in the Axis of the Cylinder.

What raifos the Water at the fide of the Veffel, which occafions the Cavity in the Middle, is its centrifugal Force.— For the Motion of the Water being circular, it refpects a Centre taken in the Axis of the Veffel, or, which is the fame, in the Axis of the Vortex form'd by the Water; the fame Velocity, then, being imprefs'd on all the Water, the Circumference of a fmaller Circle of Water, or a Circle lefs remote from the Axis, has a greater centrifugal Force than another that is greater, or more remote from the Axis. The fmaller Circle therefore drives the greater towards the fide of the Veffel, and from this Preffion or Impulfion which all the Circles receive from the fmaller ones that precede them, and convey to the greater which follow them, arifes that Elevation ov the Water along the Edge of the Veffel to the very top, where we fuppofe the Motion to ceafe.

With a Vortex thus form'd, M. Saulmon, of the Royal Academy of Sciences, made divers Experiments by putting faveral folid Bodies therein, to acquire the fame circular Motion; with Intent to difcover which of them, in making their Revolutions round the Axis of the Vortex, approach towards, or recede from ir, and with what Velocity.— The Rcfult was, that the heavier the Body, ftill the greater was its Recefs from the Axis.

M. SaulmonW\cw in this Attempt, was to fhew how the Laws of Mechanicks produce the cceleftial Motions; and that it is probably to thofe Motions that the Gravity or Weight of Bodies is owing.— But, unhappily, the Experiments fhew iuft the contrary of what they fhould do, to confirm the 'Carte/tan DoSi-ine of Gravity. See Gravity.

Vortex, in the Cartefian Philofophy, is a Syftem or Col- lection of Particles of Matter moving the fame way, and round the fame Axis.

Such Vortices are the Grand Machines whereby thefe Philofophers folve mod of the Motions and other Phenomena of the heavenly Bodies. — Accordingly, the Doctrine of thefe Vortices makes a great part of the Cartefian Philofophy. See Cartesian ism.

The Matter of the World, they hold to have been divi- ded at the Beginning into innumerable little equal Particles, each endow'd with an equal Degree of Motion, both about its own Centre and feparately, fo as to conftitute a Fluid.

Several Syftems, or Collections of this Matter, they fur- ther hold to have been endow'd with a Motion about certain Points as common Centres, placed at equal Distances; and that the Matters moving, round thefe, compos'd fo many

Then, the primitive Particles of Matter they fuppofe, by thefe inteftine Motions, to be as it were ground into fpherical Figures, and fo to compofe Globules of divers Magnitudes; which they call the Matter of the Second Element : and the Particles rubb'd or ground offthem, to bring them to thatForm, , they call the Matter of the Fir ft Element. See Element. And fince there would be more of this Firjl Element than would fuffice to fill all the Vacuities between the Globules of the Seco?id, they fuppofe the remaining Part to be driven towards the Centre of the Vortex, by the circular Motion of

the Globules; and that being there amafs'd into a Sphere* it would produce a Body like the Sun. See Sun.

This Sun being thus form'd, and moving about its own Axis with the common Matter of the Vortex, would necef- farily throw out fome Parts of its Matter, thro' the Vacuities of the Globules of the Second Element constituting the Vor- tex; and this efpecially at fuch Places as are farther! from its Poles; receiving, at the fame time, in by thefe Poles, as much as it lofes in its equatorial Parts. And by this means it would be able to carry round with it thofe Globules that are nearcft, with the greater Velocity, and the remoter, with lefs. And by this means thofe Globules which are near- eft the Centre of the Sun rnuft be leaft; becaufe were they greater, or equal, they would, by reafon of their Velocity, have a greatercentrifugal Force, and recede from the Centre. See Light.

If it fhould happen that any of thefe Sun-like Bodies in the Centres of the feveral Vortices, fhould be fo incruftated and weakened, as to be carried about in the Vortex of the true Sun; if it were of lefs Solidity, or had lefs Motion than the Globules towards the Extremity of the Solar Vortex; then it would defcend towards the Sun, till it met with Globules of the fame Solidity, and capable of the fame Decree of Motion with itfelf; and thus, being fix'd there, it would be forever after carried about by the Motion of the Vortex^ without either approaching any nearer to, or receding from the Sun; and fo become a 'Planet. See Planet.

Suppofing then all this, we are next to imagine that our Syftem was at firft divided into feveral Vortices, in the Cen- tre of each of which was a lucid fpherical Body; and that fome of thefe being gradually incruftated, were fwallowcd up by others which were larger and more powerful, till at laft they were alt deftroy'd and fwallow'd up by the biggeft Solar Vortex, except fome few which were thrown off in right Lines from one Vortex to another, and fo became Co- mets. See Comet.

But this Doctrine of Vortices, is at beft merely hy- pothetical. — It does not pretend to /hew by what Laws and Means rhe cceleftial Motions are reaiiy effected, fo much as by what Means they poffibly might, in cafe it fhould have fo pleas'd the Creator.— But we have another Principle which accounts for the fame Phenomena as well, nay better than that of Vortices; and which we plainly find has an actual Exiflence in the Nature of Things : And this is Gravity^ or the weight of Bodies. See Gravity.

The Vortices, then, fliould be caft out of Philofophy, were it only that two different adequate Caufes of the fame Phenomena are inconfiftent. See Newtonian 'Philofophy '.- But we have other Objections againftit. — For i°, If the Bodies of the Planets and Comets be carried round the Sun in Vortices, the Bodies of the Parts of rhe Vortex immedi- ately invefting era, rnuft move with the fame Velocity, and in the fame Direction; and befides, muft have the fame

Denfity, or the fame vis Inertice. But it is evident, that

the Planets and Comets move in the very fame Parts of the Heavens with different Velocities, and in different Directions. It follows, therefore, that thofe Parts of the Vortex muft re- volve at the fame time in different Directions, and with different Velocities; fince one Velocity and Direction will be required for the Paffage of the 'Planets, and another for that of the Comets.

2, If it were granted, that feveral Vertices are contain'd in the fame Space, do penetrate each other, and revolve with divers Motions; fince thofe Motions muft be conform- able to thofe of the Bodies, which are perfectly regular, and perform'd in Conic Sections; it may be afk'd, How they fhould have been preferv'd entire fo many Ages, and not difturb'd and confounded by the adverfc Actions and Shocks of fo much Matter as they meet withal?/

3, The Number of Comets is very great, and their Mo- tions perfectly regular, obferving the fame Laws with the 'Planets, and moving in conical Orbits, that are exceedingly excentric. Accordingly they move every Way, and to all Parts of the Heavens, freely pervading the planetary Re- gions, and going frequently contrary to the Order of the Signs; which were impoffible, unlefs thefe Vortices were away.

4, If the 'Planets moved round the Sun in Vortices, thofe Parts of the Vortices next the 'Planets, we have already ob- ferved, would be equally denfe with th.z'Planets themfelves: Confequently the vortical Matter contiguous to the Perimeter of the Earth's Orbit, would be as denfe as the Earth itfelf: And that between the Orbits of the Earth and Saturn, muft: be as denfe, or denfer. — For a Vortex cannot maintain it felf, unlefs the more denfe Parts be in the Centre, and the lefs denfe towards the Circumference : And fince the perio- dical times of the Planets are in a fefquialterate Ratio of their Diftances from the Sun, the Parts of the Vortex muft be in the fame Ratio. Whence it follows, that the centri- fugal Forces of the Parts will be reciprocally as the Squares

of the Diftances. -Such, therefore, as are at a greater

diftance from the Centre, will endeavour to recede there- from