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a wire of any imaginary length be supported with silken strings through ever so many rooms, and back again, one end of which to communicate with the prime conductor; by this means, when the wheel is in motion, the whole length of the wire will be electrised, i. e. the active fluid will be accumulated on every part, as may be easily proved by drawing sparks from it, and by seeing how briskly light bodies are agitated, when placed near to any part of it on a plate : But if any part of the wire be made to communicate with the floor either directly or indirectly, all the Phænomena seem then at an end. To illustrate this : Let a Perfon take hold of the insulated wire, even at the remotest part from the Machine, and all the afore-mentioned accumulation vanilhes ; the light bodies all lie still on the plațe, nor can any spark be drawn from any part of the Apparatus : A Person therefore unacquainted with those experiments would think all was at an end; whereas the fluid is all the time swiftly paffing into the earth through the internal subItance of the wire, and through the Person who holds it at the end. To prove this : Let the supported wire be clipp'd afunder at parts where it is so supported, that the two ends may not drop from each other, and the Fire will plainly appear

between

every tion, even though the experiment were made at noon day : Then let the Person releafe the und of the wire, or else step on the Resin-cake

(either

such separa

H2

(either of which cuts off the communication with the earth) and then the accumulation again takes place; the light bodies also on the

plate will be in motion as before, but no Fire * appears at the separations; for that Phænome

non never happens, unless the part of the wire beyond the separations communicates with the floor, 107,

Another effectual method to prove that it moves through the internal parts of nonelectrical bodies, may be the following:

108. Let Four Corks be fitted to a glass Tube as A B, having a wire through each of them ; and two of those Corks as CD, with their wires gh, and k l, be thrust in towards the middle of the Tube, fo far, that the two Loops of the wires h and k, which project beyond the ends of the Corks, may come near each other in the middle of the Tube. After which, let the two ends of the Tube E F, be filled with water, and then stopped with the other two Corks G and H. PI. II. Fig. 1.

103. Let the glass thus prepared be made a part of the foremention'd Line of insulated wires, by taking out a part of the wire, and putting the tube in its stead ; This line thus compounded of the prime conductor, the divided wires and the water-tube, will still ans swer the same ends as before in every respecte A Person standing on the Resin and communicating with the extremity or other parts of the wire is electrised in the same manner as at other

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times : The firė appears at every feparation of the wire as before, if a spark be drawn from the electrised Perfoni, or the wire with which he communicates.

119. And in a word, the propensity of this elastic fluid to maintain an equilibrium among all its parts is so amazingly great, that if a spark be drawn off, tho’ from the most diftant

part, a corresponding spark appears, not only at each feparation of the wires, but also between the two wires in the middle of the water-tube.

11. Having thus far consider'd the great subtilty and elasticity of the electrical Medium, I shall in the following Chapter explain more particularly the natural effect of an elastic fluid, viz. that of its expanding.

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Intumescence, &c. of an elastic Fluid.

*NTUMESCENCE is that Proen I perty of an elastic Fluid, of expanding, Young

Jwelling, and constant endeavour of ex

tending itself to larger Dimenfions. . I 113. « This will be the better understood, if with Mr. Boyle, we conceive the primary Par

ticles,

is continued; but when that is át an End, the accumulation lessens, and the sides of the Triangle contract, gently and gradually, till the Corks meet. Balls of Lead, if suspended to such Threads, will when electris'd repel each other in the same manner, and to as great a Distance, if their Threads are sufficiently lengthened-t.

120. Fourthly. That the primary and secondary Air mutually repel each other.

This is put paft dispute from the effects of the following

EXPERIMEN T. 121. If a piece of Wire of about Six Inéhes in length be pointed at each end, and those ends turn'd different ways, as in Pl. II. fig. 2. and that wire be suspended on the point of a Needle, erected for that purpose on the prime Conductor of the Machine, in the manner a magnetic Needle is suspended ; this pois'd Wire is no fooner electris'd, than the fiery Particles begin to be hurried off as usual at the Points; thofe

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† Every particle of Matter electrified is mutu• ally repelled by every other neighbouring particle

equally electrified. Thus, the stream of a fountain, naturally dense and continual, when electrified,

will separate and spread in the form of a Brush, ļ every drop (or particle of the Water thus electrified) < endeavouring to recede from every other particle.

But on taking away that electrical Fire, they close

again,' like the cork Balls. See Mr. Franklin's Letters on Electricity. p. 37: 2d. Edition."

elastic

elastic Particles striking the elastic Air mutua ally repel, and consequently the repelld points of the Wire will give way, and fly back; which Motion of the Wire will increase, till it becomes as rapid as the Flyers of a Jack, so that when the Room is darken'd, à circle of Fire is formed *

Since then the primary and secondary airTo manifestly repel each other, can it be reaTonably doubted, whether the retension of the former, in the experiments, which accumulates on gross bodies (instead of dispersing). be from the effect of the repelling spring of the latter surrounding it for otherwise, by means of its great Elasticity and Subtilty, it must necessarily escape, as soon and as fast as collected. But the elasticity of the ætherial particles contain'd in it, suffers not the include

* The fiery particles, issuing from pointed bodies when electris’d, have an exceeding lively refem blance of the fiery particles issuing from the mout! of a squib or ferpent, when kindled; which diverge and recede from each other, in the same manner with those of the artificial fire-work, (particularly when they are faften'd to the circumference of a wheel,) and each of those appears to act from the very fame principle; tho' it must indeed be allow'd, that the smallness of the aperture of a serpent, throwhich the fiery particles force their way, very

much accelerates, the motion on the wheel. The elastic particles of each one, striking against the elastie air, recoil, and are repellid back.

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