Page:Cyclopaedia, Chambers - Volume 1.djvu/100

 A I R

C55 )

ALA

w-' III a Vcffel exhaufted by the Air-Pump, the primitive c or natural Air contained therein, is to the Air remaining, ' as the Aggregate of the Capacity of the Veffel and of the ' Tump, (*'• e. the Cylinder left vacant in an Elevation ' of the Pifton, with the Wire and ether Parts between the ' Cylinder and Receiver) rais'd to a Tower ichofe Exponent <■ is equal to the Number of Strokes cf the Pifton, to the ' Capacity of the Vejfel alone raifed to the fame 'Power.'

M. Varigmn gives an Algebraical Demonftration of this Theorem, in the Memoires de I' Acad. R. An. 1705. p. 397,

but it may be alfo demonfttated pneumatically, thus : ■

Calling the Air remaining after the firft Stroke, the firft Refidual-, that after the fecond, the fecoud Refidual, &c. and remembering that the Air in the Receiver is of the fame Denfity as that in the Cylinder, when the Pifton is raifed : it is evident, that the Quantity of Air in the Recei- ver, is to the Quantity of Air in theCylinder.Wire, tyc. as the Capacity of the Receiver to that of the Cylinder, iSc. and confequenrly, the Aggregate of the Air in the Receiver and the Cylinder, i. e. the whole primitive Air, is to the Air in the Veffel alone, i. e. to the firlt Refidual Air, as the Aggregate of the Capacity of the Receiver and the Cy- linder, to the Capacity of the Receiver alone. — After the fame manner may it be proved, that the Quantity of firft re- fidual Air, is to the fecond Refidual, as the Aggregate of the Capacity of the Receiver and Cylinder, to the Capa- city of the Vcffel alone. And the fame Proportion does the fecond Refidual bear ro the third, and fo of

the reft. Hence, the Product of the primitive Air

into the firft, fecond, third, fourth, iSc. Refiduals, is to the Product of the firil Refidual into the fecond, third, fourth, fifth, &fe. as the Product of the Capacity of the Receiver and Cylinder together, multiplied as oft into it felf as the Number of Strokes of the Pillon contains Units ; to the Faftum atifing from the Capacity of the Receiver alone, multiplied fo often by it felf: That is, As the Power of the Aggregate of the Capacity of the Receiver and Cylinder together, whole Exponent is the Number of Strokes of the Pillon, to the Capacity of the Veffel alone, raifed to the fame Power. — Confequently the primitive /lir is to the lait Refidual, in ihc Ratio of thofe Powers. #. E. 2).

2, The Number of Strokes of the Piiton, together with the Capacity of the Receiver and Cylinder wirh the Wire, $3c. being given ; to find the Ratio of the primitive Air to the Air, remaining.

Subtract the Logarithm of the Capacity of the Receiver, from that of the Sum of the Capacity o\~ the Receiver and the Cylinder ; rhen, the Remainder being multiplied by the JMumber of Strokes of the Piiton, the Product will be a Logarithm, whofe Natural Number thews how oft the pri- mitive Air contains 1 the Remainder requir'd.

Thus, if the Capacity of the Receiver be 460, that of the Cylinder 580, and the Number of Strokes of the Pillon 6 5 the primitive Air wiil be found to the remaining Air, as I4<i$ff » 1.

For, fuppofe the Capacity of the Veffel =0 ; that of the Cylinder and Veffel together, ~a ; the Number of Strokes of the Piiton =re ; and the remaining Air — 1. Since the Primitive is to the remaining Air as a n to v n 5 the primitive Mir will alfo be to the remaining Air, as a" -. v" to 1. Confequently, if the remaining Air be 1, the Logarithm of the primitive Air ha — vxn.

3, The Capacity of the Receiver and the Barrel being given j to find the Number of Strokes of the Pifton required to rarify the Air to a given Degree.

Subtract the Logatithm of the remaining Air from the Logarithm of the primitive Air ; and the Logarithm of the Capacity of the Receiver, from the Logarithm of the Ag- gregate of the Capacity of the Receiver and Cylinder ; then, dividing the former Difference by the latter, the Quo- tient is the Number cf Strokes requir'd.

Thus, if rhe Capacity of the Cylinder be fuppofed 580 ; that of the Receiver 460 ; and the primitive Air to the remaining Air, as 1464 to 10 : The Number of Strokes required will be found to be 6.

Befide the Effects, and Phenomena of the Air-Tump, re- counted under the Articles Vacuum, Air, &c. we may add fome others 5 which, related at large, make the Sub- flance of Mr. Boyle's 'Phyf. Mech. Exper. As, — That the Flame of a Candle ufually goes out in a Minute, tho it fometimes laits two, but the Wieck theteof continues ignited after ; and even emits a Smoke, which afcends upwards. — ■ That a kindled Charcoal is totally extinguiift'd in about five Minutes, tho in open Air it remain alive half an Hour ; and that it goes out by degrees, beginning from the Top and the Outfides. — That red-hot Iron is not affected by the Ab- fence of the Air 5 and yet that Sulphut or Guneouder will not be lighted thereby, but only fufed. — That a Match, after lying feemingly extinct in Vacuo, a long time j revives again upon the Re-admiffion of the Air. — That a Flint and Steel ftrikc Sparks of Fire as copioully in Vacuo as out of it $ and that the Spatks move in all Directions, upwards, down-

wards, &c. here,' as ir 1 the ^/r.-That Magnets and Mag- netick Needles are the fame in Vacuo as in Air -That Smoke in an exhausted Receiver, the Luminary being ex- tfflflj gradually fettles to the Bottom in a darkifh Body leaving the upper part clear and ttanfpatent ; and that in- clining the Vcffel fometimes on one fide, and fometimes on another, the Fume keeps its Surface horizontal, after the Nature of other Fluids.— That the Syphon docs not run in

Vacuo.- that Water freezes in Vacuo.— That Heat may

be produced by Attrition in the exhaufted Receiver. -

That Camphire will not take fire in Vacuo ;.and that Gun- pouder, tho fome Grains of a Heap be kindled by a Burmng-glafs in Vacuo, will not give Fire to the conti- guous Grains. That Glow worms lofe their Light, in

proportion as the Air is exhaufted ; and at length be- come totally oblcure : but upon the Re-admiffion of Air, prefently recover it all.— That Vipers and Frogs fwell much in Vacuo, but will live an Hour and half, or two Hours ; and tho feemingly ftark dead in that time, come to Life again in fome Hours in rhe Air.— That Snails furvive ten Hours ; and Efts or Slow-worms, two or three Days ; Lea- ches five or fix.— That Oyftcrs will remain alive in Vacuo 24 Hours without hatm.— That the Heart of an Eel taken out of the Body, continues to beat in Vacuo, more nimbly than in Air ; and this for a good part of an Hour.— That warm Blood, Milk, Gall, (gc. undergo a confidcrabie Intu- mescence, and Ebullition in Vacuo.— That a Moufe, or otnet Animal, may be brought, by degrees, to furvive lon- ger in a ranfied Air, than naturally it docs.— That Air tray retain its ufual Pieffurc, after it is become unfit fot Refpira- tion.— That Silk-Wotms Eggs will hatch in Vacuo, &c.

AIRY, or Am ie, of Hawks. See Aery.

Airy Triplicity, among AOrologers, the Signs of Gemini, Libra, and Aquarius. See Tiuplicity.

AISIAMENTA, in Law. See Easements.

AJUSTING. Sec Accommodation.

AJUTAGE, in Hydraulicks, part of the Apparatus of an artificial Fountain, or Jet d'Eau ; being a fort of Tube, fitted to the Mouth or Aperture of the Veffel ; thro' which, the Water is to be play'd, and by it determin'd into this or that Figure.

, ' Tis cl ^fly the Divcrfity in the Ajutages, that makes the different Kinds of Fountains.— And hence, by having feveral Ajutages to be applied occafionally, one Fountain comes to have the Efiect of many.

'the various forts of Ajutages, their StruBure, Appli- cation, &c. fee under the Article lorn-thin.

The Word is French, form'd of rhe Verb Ajouter, to adjuft.

AKOND, an Officer of Juftice in Perfia,' who takes cog- nizance of the Caufes of Orphans, and Widows ; of Con- traas, and other Civil Concerns.— He is Head of the School ot Law, and gives Lcaures to all the fubaltetn Officers ; he has his Deputies in all the Courts of the Kingdom, who, with the fecond Sadra, make all Contraas.

AL, an Arabick Particle, prcfix'd to Words to exalt or give them a mote emphatical Signification.— As, in ^chvmv, /fflgebra, 0?c. '...»'•

Ae, or Alii, in our antient Cuftoms, fignifies as much as old, antient.— This, being prefix'd ro the Names of Pla- ces expreffes their Antiquity ; as Aldborough, Aldgatc, &c.

A'LA.a.ZatniTerm, literally fignifying Wing. See Wing.

Ala is alfo ufed in Anatomy, for feveral Parts of the Bo- dy, which bear fome refemblance to the Figure of a Wing.

Thus, the Lobes of the Liver are fometimes called Al£. See Lore.

The foft, fpongious Bodies in the Tudendum Muliehre, ufually called the Nymphs, are alfo denominated Al<e. See

NyMI'HJE.

The two Cartilages of the Nofe which form the Noftrils, are alfo called Ale. See Nose, and Nostril.

And the fame Denomination is given to the Top of the Auricle. See Auricle, and Ear.

Ala is alfo ufed in Botany, for rhe Angle which the Leaves, or the Stalks or Pedicles of the Leaves, form with the Stem or Branches of a Plant from which they arife: See Leave, E?c.

This Angle is ufually acute, and always direaed up- wards. — The fame Name is occafionally applied to the An- gle form'd by the Branches themfelvcs, with the Stem ; which is alfo obferved to be very regular and uniform. See Branch.

ALjE, in the Military Art, are the two Extremes of an Army, ranged in form of Battle. See Wing, Army, i$c.

ALABASTER, Alabastrides, in Natural Hillory, a kind of Stone, fofter than Marble, yet harder than Plaifter of Paris. See Stone.

It is found of all Colours ; fome extremely white and ihining, wn i c h is the moft common ; fome red, like Coral 5 and other called Onyx from its Colour, which refembles that of the Onyx, tho very different from it in Nature. See Onyx. «,


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