« AnteriorContinuar »
and discharging the phial, it is in compliance tracted; if either of these two operations be with custom, and for want of others more suit- hindered, the other cannot be done. But the able. Since we are of opinion that there is spring is not said to be charged with elasticity really no more electrical fire in the phial af- when bent, and discharged when unbent; its ter what is called its charging, than before, quantity of elasticity is always the same. nor less after its discharging ; excepting on. 13. Glass in like manner, has, within its ly the small spark that might be given to, and substance, always the same quantity of electaken from the non-electric matter, if sepa- trical fire, and that a very great quantity in rated from the bottle, which spark may not be proportion to the mass of glass, as shall be equal to a five hundredth part of what is called shown hereafter. the explosion.
14. This quantity, proportioned to the glass, For, if on the explosion, the electrical fire it strongly and obstinately retains, and will came out of the bottle by one part, and did have neither more nor less, though it will not enter in again by another, then, if a man, suffer a change to be made in its parts and standing on wax, and holding the bottle in situation; i. e. we may take away part of it one hand, takes the spark by touching the from one of the sides, provided we throw an wire hook with the other, the bottle being equal quantity into the other. thereby discharged, the man would be charg 15. Yet when the situation of the electried; or whatever fire was lost by one, would cal fire is thus altered in the glass; when be found in the other, since there was no way some has been taken from side, and some adfor its escape: but the contrary is true. ded to the other, it will not be at rest or in
9. Besides, the phial will not suffer what is its natural state, till it is restored to its origicalled a charging, unless as much fire can go nal equality. And this restitution cannot be out of it one way, as is thrown in by another. made through the substance of the glass, but A phial cannot be charged standing on wax must be done by non-electric communication or glass, or hanging on the prime conductor, formed without, from surface to surface. unless a communication be formed between 16. Thus, the whole force of the bottle, and its coating and the floor.
power of giving a shock, is in the GLASS IT10. But suspend two or more phials on the SELF; the non-electrics in contact with the prime conductor, one hanging on the tail of two surfaces, serving only to give and receive the other; and a wire from the last to the to and from the several parts of the glass; floor, an equal number of turns of the wheel that is, to give on one side, and take away from shall charge them all equally, and every one the other. as much as one alone would have been. 17. This was discovered here in the followWhat is driven out at the tail of the first, ing manner: purposing to analyse the elecserving to charge the second; what is driven trified bottle, in order to find wherein its out of the second, charging the third ; and so strength lay, we placed it on glass, and drew on. By this means a great number of bottles out the cork and wire which for that purpose might be charged with the same labour, and had been loosely put in. Then taking the equally high, with one alone; were it not bottle in one hand, and bringing a finger of that every bottle receives new fire, and loses the other near its mouth, a strong spark came its old with some reluctance, or rather gives from the water, and the shock was as violent some small resistance to the charging, which as if the wire had remained in it, which showin a number of bottles becomes more equal to ed that the force did not lie in the wire. Then the charging power, and so repels the fire back to find if it resided in the water, being crowdagain on the globe, sooner in proportion than ed into and condensed in it, as confined by the a single bottle would do.
glass, which had been our former opinion, we 11. When a bottle is charged in the com- electrified the bottle again, and placing it on mon way, its inside and outside surfaces glass, drew out the wire and cork as before ; stand ready, the one to give fire by the hook, then taking up the bottle, we decanted all the other to receive it by the coating; the one its water into an empty bottle, which likeis full, and ready to throw out, the other wise stood on glass; and taking up that other empty and extremely hungry; yet as the first bottle, we expected, if the force resided in the will not give out, unless the other can at the water, to find a shock from it; but there was same instant receive in ; so neither will the none. We judged then that it must either be latter receive in, unless the first can at the lost in decanting, or remain in the first bottle. same instant give out. When both can be done The latter we found to be true; for that bottle at once, it is done with inconceivable quick- on trial gave the shock, though filled up as it ness and violence.
stood with fresh unelectrified water from a 12. So a straight spring (though the com- tea-pot. To find, then, whether glass had parison does not agree in every particular) this property merely as glass, or whether the when forcibly bent, must, to restore itself, form contributed any thing to it; we took a contract that side which in the bending was pane of sash-glass, and laying it on the hand, extended, and extend that which was con- placed a plate of lead on its upper surface;
then electrified that plate, and bringing a 20. The magical picture* is made thus : finger to it, there was a spark and shock. We Having a large mezzotinto with a frame and then took two plates of lead of equal dimen- glass, suppose of the KING, take out the print, sions, but less than the glass by two inches and cut a pannel out of it near two inches every way, and electrified the glass between distant from the frame all around. If the cut them, by electrifying the uppermost lead; is through the picture it is not the worse. then separated the glass from the lead, in do- With thin paste, or gum water, fix the border ing, which, what little fire might be in the that is cut off on the inside the glass, pressing lead was taken out, and the glass being it smooth and close; then fill up the vacancy touched in the electrified parts with a finger, by gilding the glass well with leaf-gold, or afforded only very small pricking sparks, but brass. Gild likewise the inner edge of the a great number of them might be taken from back of the frame all round, except the top different places. Then dextrously placing it part, and form a communication between that again between the leaden plates, and com- gilding and the gilding behind the glass : pleting a circle between the two surfaces, a then put in the board, and that side is finished. violent shock ensued; which demonstrated Turn up the glass, and gild the foreside exthe power to reside in glass as glass, and that actly over the back gilding, and when it is the non-electrics in contact served only, like dry, cover it, by pasting on the pannel of the the armature of a loadstone, to unite the picture that hath been cut out, observing to force of the several parts, and bring them at bring the correspondent parts of the border once to any point desired : it being the pro and picture together, by which the picture perty of a non-electric, that the whole body will appear of a piece, as at first, only part is instantly reccives or gives what electrical fire behind the glass, and part before. Hold the is given to or taken from any one of its parts. picture horizontally by the top, and place a lit
18. Upon this we made what we called antle moveable gilt crown on the king's head. If electrical battery, consisting of eleven panes now the picture be moderately electrified, and of large sash-glass, armed with thin leaden another person take hold of the frame with one plates, pasted on each side, placed vertically, hand, so that his fingers touch its inside gildand supported at two inches distance on silk ing, and with the other hand endeavour to cords, with thick hooks of leaden wire, one take off the crown, he will receive a terrible from each side, standing upright, distant from blow, and fail in the attempt. If the picture each other, and convenient communications were highly charged, the consequences might of wire and chain, from the giving side of one perhaps be as fatalt as that of high treason, pane, to the receiving side of the other; that for when the spark is taken through a quire so the whole might be charged together, and of paper laid on the picture by means of a with the same labour as one single pane; and wire communication, it makes a fair hole another contrivance to bring the giving sides, through every sheet, that is, through fortyafter charging, in contact with one long wire, eight leaves, though a quire of paper is thought and the receivers with another, which two good armour against the push of a sword, or long wires would give the force of all the even against a pistol bullet, and the crack is plates of glass at once through the body of exceeding loud. The operator, who holds any animal forming the circle with them. the picture by the upper end, where the inside The plates may also be discharged separately, of the frame is not gilt, to prevent its falling, or any number together that is required. But feels nothing of the shock, and may touch the this machine is not much used, as not per- face of the picture without danger, which he fectly answering our intention with regard to pretends is a test of his loyalty - If a ring of the ease of charging, for the reason given sec. persons take the shock among them, the ex10. We made also of large glass panes, ma- periment is called The Conspirators. gical pictures, and self-moving animated 21. On the principle, in sec. 7, that hooks wheels, presently to be described.
of bottles, differently charged, will attract and 19. I perceive by the ingenious Mr. Wat- repel differently, is made an electrical wheel, son's last book, lately received, that Dr. Bevis that turns with considerable strength. A had used, before we had, panes of glass to small upright shaft of wood passes at right angive a shock ;* though, till that book came to gles through a thin round board, of about hand, I thought to have communicated it to twelve inches diameter, and turns on a sharp you as a novelty. The excuse for mentioning point of iron, fixed in the lower end, while à it here is, that we tried the experiment differ- strong wire in the upper end, passing through ently, drew different consequences from it a small hole in a thin brass plate, keeps the (for Mr. Watson still seems to think the fire shaft truly vertical. About thirty radii of accumulated on the non-electric, that is in con- equal length, made of sash-glass, cut in nartact with the glass, p. 72) and, as far as we row strips, issue horizontally from the cirhitherto know, have carried it farther.
* Contrived by Mr. Kinnersly.
We have since found it fatal to small animals, * I have since heard that Mr. Smeaton was the first though not to large ones. The biggest we have yet who made uae of panes of glass for that purpose. killed is a hen. 1750.
cumference of the board, the ends most dis- | surface of the wheel; and about six inches tant from the centre being about four inches from it is another bullet, communicating in apart. On the end of every one a brass like manner with the under surface. When thimble is fixed. If now the wire of a bot- the wheel is to be charged by the upper surtle electrified in the common way, be brought face, a communication must be made from the near the circumference of this wheel, it will under surface to the table. When it is well attract the nearest thimble, and so put the charged it begins to move; the bullet nearest wheel in motion; that thimble, in passing by, to a pillar moves towards the thimble on that receives a spark, and thereby being electrified pillar, and passing by electrifies it, and then is repelled, and so driven forwards; while a pushes itself from it; the succeeding bullet, second being attracted, approaches the wire, which communicates with the other surface receives a spark, and is driven after the first, of the glass, more strongly attracts that thimand so on till the wheel has gone once round, ble, on account of its being before electriwhen thimbles before electrified approaching fied by the other bullet; and thus the wheel the wire, instead of being attracted as they increases its motion till it comes to such a were at first, are repelled, and the motion pre- height as that the resistance of the air regusently ceases. --But if another bottle, which lates it. It will go half an hour, and make had been charged through the coating, be one minute with another twenty turns in a miplaced near the same wheel, its wire will at- nute, which is six hundred turns in the whole; tract the thimble repelled by the first, and the bullet of the upper surface giving in each thereby double the force that carries the wheel turn twelve sparks to the thimbles, which round; and not only taking out the fire that makes seven thousand two hundred sparks; had been communicated to the thimbles by and the bullet of the under surface receiving the first bottle, but even robbing them of their as many from the thimbles; those bullets natural quantity, instead of being repelled moving in the time near two thousand five when they come again towards the first bot- hundred feet. The thimbles are well fixed, tle, they are more strongly attracted, so that and in so exact a circle, that the bullets may the wheel mends its pace, till it goes with pass within a very small distance of each of great rapidity twelve or fifteen rounds in a them.-If instead of two bullets you put eight, minute, and with such strength, as that the four communicating with the upper surface, weight of one hundred Spanish dollars with and four with the under surface, placed alterwhich we once loaded it, not seem in the nately, with eight, at about six inches disleast to retard its motion—This is called an tance, completes the circumference, the force electrical jack; and if a large fowl were spit- and swiftness will be greatly increased, the ted on the upright shaft, it would be carried wheel making fifty turns in a minute; but round before a fire with a motion fit for then it will not continue moving so long.-roasting.
These wheels may be applied, perhaps, to the 22. But this wheel, like those driven by ringing of chimes,* and moving of light-made wind, water, or weights, moves by a foreign orreries. force, to wit, that of the bottles. The self 23. A small wire bent circularly, with a moving wheel, though constructed on the loop at each end ; let one end rest against the same principles, appears more surprising. It under surface of the wheel, and bring the is made of a thin round plate of window glass, other end near the upper surface, it will give seventeen inches diameter, well gilt on both a terrible crack, and the force will be dissides, all but two inches next the edge. Two charged. small hemispheres of wood are then fixed with 24. Every spark in that manner drawn cement to the middle of the upper and under from the surface of the wheel, makes a round sides, centrally opposite, and in each of them hole in the gilding, tearing off a part of it in a thick strong wire eight or ten inches long, coming out; which shows that the fire is not which together make the axis of the wheel. accumulated on the gilding, but is in the glass It turns horizontally on a point at the lower itself. end of its axis, which rests on a bit of brass 25. The gilding being varnished over with cemented within a glass salt-cellar. The up- turpentine varnish, the varnish though dry per end of its axis passes through a hole in a and hard, is burnt by the spark drawn through thin brass plate cemented to a long strong it, and gives a strong smell and visible smoke. piece of glass, which keeps it six or eight inch- And when the spark is drawn through paper, es distant from any non-electric, and has a all round the hole made by it, the paper will small ball of wax or metal on its top, to keep in be blacked by the smoke, which sometimes the fire. In a circle on the table which supports penetrates several of the leaves. Part of the the wheel, are fixed twelve small pillars of gilding torn off is also found forcibly driven glass, at about four inches distance, with a into the hole made in the paper by the stroke. thimble on the top of each. On the edge of 26. It is amazing to observe in how small the wheel is a small leaden bullet, communi
* This was afterwards done with success by Mr. Kin. eating by a wire with the gilding of the upper nersley.
a portion of glass a great electral force may suspended by a silk thread, hang in contact lie. A thin glass bubble, about an inch di with the shot. Take a bottle in each hand, ameter, weighing only six grains, being half one that is electrified through the hook, the filled with water, partly gilt on the outside, other through the coating : apply the giving and furnished with a wire hook, gives, when wire to the shot, which will electrify it po electrified, as great a shock as a man can sitively, and the cork shall be repelled: then well bear. As the glass is thickest near apply the requiring wire, which will take out the orifice, I suppose the lower half, which the spark given by the other; when the cork being gilt was electrified and gave the shock, will return to the shot: apply the same again, did not exceed two grains ; for it appear- and take out another spark, so will the shot ed when broken, much thinner than the up- be electrified negatively, and the cork in that per half.- If one of these thin bottles be case shall be repelled equally as before. Then electrified by the coating, and the spark taken apply the giving wire to the shot, and give out through the gilding, it will break the the spark it wanted, so will the cork return: glass inwards, at the same time that it breaks give it another, which will be an addition to the gilding outwards.
its natural quantity, so will the cork be re27. And allowing (for the reasons before pelled again, and so may the experiment be given, § 8, 9, 10,) that there is no more elec- repeated as long as there is any charge in the tral fire in a bottle after charging, than be bottles. Which shows that bodies, having fore, how great must be the quantity in this less than the common quantity of electricity, small portion of glass ! It seems as if it were repel each other, as well as those that have of its very substance and essence. Perhaps more. if that due quantity of electral fire so obsti Chagrined a little that we have been hithernately retained by glass, could be separated to able to produce nothing in this way of use from it, it would no longer be glass; it might to mankind; and the hot weather coming on, lose its transparency, or its brittleness, or its when electrical experiments are not so agreeelasticity. Experiments may possibly be in- able, it is proposed to put an end to them for vented hereafter, to discover this.
this season, somewhat humourously, in a 28. We were surprised at the account party of pleasure, on the banks of Schuylkill.* given in Mr. Watson's book, of a shock com- Spirits at the same time, are to be fired by a municated through a great space of dry spark sent from side to side through the river, ground, and suspect there must be some me- without any other conductor than the water; talline quality in the gravel of that ground ; an experiment which we some time since perhaving found that simple dry earth, rammed formed, to the amazement of many.t. A turin a glass tube, open at both ends, and a wire key is to be killed for our dinner by the elechook inserted in the earth at each end, the trical shock, and roasted by the electrical jack, earth and wires making part of a circuit, before a fire kindled by the electrified bottle : would not conduct the least perceptible shock, when the healths of all the famous elecand indeed when one wire was electrified, the tricians in England, Holland, France, and other hardly showed any signs of its being in Germany are to be drank in electrified bumconnexion with it.* Even a thoroughly wet pers, f under the discharge of guns from the packthread sometimes fails of conducting a electrical battery. shock, though it otherwise conducts electricity very well. A dry cake of ice, or an icicle
* The river that washes the west side of Philadelphia,
as the Delaware does the east side. held between two in a circle, likewise pre As the possibility of this experiment has not been vents the shock, which one would not expect, easily conceived, I shall here describe it.-Two iron as water conducts it so perfectly well.-Ġild- rods, about three feet long, were planted just within the ing on a new book, though at first it conducts piece of wire, with a small round knob at its end, was the shock extremely well, yet fails after ten fixed on the top of one of the rods, bending downwards, or a dozen experiments, though it appears face of the spirit. A small wire fastened by one end otherwise in all respects the same, which we
to the handle of the spoon, containing the spirit, was
carried across the river, and supported in the air by the cannot account for.t
rope commonly used to hold by, in drawing the ferry. 29. There is one experiment more which boats over. The other end of this wire was tied round surprises us, and is not hitherto satisfactorily spark was delivered from the hook to the top of the rod accounted for; it is this : place an iron shot standing in the water on that side. At the same inon a glass stand, and let a ball of damp cork, stant the rod on the other side delivered a spark into
spoon, and fired the spirit; the electric fire returning * Probably the ground is never so dry.
to the coating of the bottle through the handle of the + We afterwards found that it failed after one stroke spoon and the supported wire connected with them. with a large bottle; and the continuity of the gold ap That the electric fire thus actually passes through the pearing broken, and many of its parts dissipated, the water, has since been satisfactorily demonstrated to electricity could not pass the remaining parts without many by an experiment of Mr. Kinnersley's, performed leaping from part to part through the air, which always in a trough of water about ten feet long. The hand resists the motion of this fluid, and was probably the being placed under water in the direction of the spark cause of the gold's not conducting so well as before; the (which always takes the strait or shortest course, if number of interruptions in the line of gold, making, sufficient, and other circumstances are equal) is struck when added together a space larger, perhaps, than the and penetrated by it as it passes. striking distance.
1 An Electrifiod bumper is a small thin glass tumbler,
To Peter Collinson, London. whirling, glass globe, during its friction Observations and suppositions, towards forming against the cushion, draws fire from the cush
a new Hypothesis for explaining the several ion, the cushion is supplied from the frame of Phenomena of Thunder-gusts.*
the machine, that from the floor on which it 1. NON-ELECTRIC bodies, that have elec- stands. Cut off the communication by thick tric fire thrown into them, will retain it till glass or wax, placed under the cushion, and other electrics, that have less, approach; and no fire can be produced, because it cannot be then it is communicated by a snap, and be collected. comes equally divided.
9. The ocean is a compound of water, a 2. Electrical fire loves water, is strongly at- non-electric, and salt an electric per se. tracted by it, and they can subsist together.
10. When there is a friction among the 3. Air is an electric per se, and when dry parts near its surface, the electrical fire is will not conduct the electrical fire; it will collected from the parts below. It is then neither receive it, nor give it to other bodies; plainly visible in the night; it appears in the otherwise no body surrounded by air, could stern and in the wake of every sailing vessel; be electrified positively and negatively: for every dash of an oar shows it, and every surf should it be attempted positively, the air and spray: in storms the whole sea seems would immediately take away the overplus; on fire.—The detached particles of water or negatively, the air would supply what was then repelled from the electrified surface, wanting
continually carry off the fire as it is collected; 4. Water being electrified, the vapours they rise and form clouds, and those clouds arising from it will be equally electrified; are highly electrified, and retain the fire till and floating in the air, in the form of clouds, they have an opportunity of communicating it. or otherwise, will retain that quantity of 11. The particles of water, rising in vaelectrical fire, till they meet with other pours, attach themselves to particles of air. clouds or bodies not so much electrified, and 12. The particles of air are said to be hard, then will communicate as before-mentioned. round, separate and distant from each other;
5. Every particle of matter electrified is every particle strongly repelling every other repelled by every other particle equally elec- particle, whereby they recede from each trified. Thus the stream of a fountain, natu- other, as far as common gravity will permit. rally dense and continual, when electrified,
13. The space between any three particles, will separate and spread in the form of a equally repelling each other, will be an equibrush, every drop endeavouring to recede lateral triangle. from every other drop. But on taking out
14. In air
compressed, these triangles are the electrical fire they close again.
in ratified air they are larger. 6. Water being strongly electrified (as well
15. Common fire, joined with air, increases as when heated by common fire) rises in va- the repulsion, enlarges the triangles, and pours more copiously; the attraction of cohe- thereby makes the air specifically lighter. sion among its particles being greatly weak- Such air, among denser air, will rise. ened, by the opposite power of repulsion in
16. Common fire, as well as electrical fire, troduced with the electrical fire ; and when gives repulsion to the particles of water, and any particle is by any means disengaged, it destroys their attraction of cohesion ; hence is immediately repelled, and so flies into the common fire, as well as electrical fire, assists air.
in raising vapours. 7. Particles happening to be situated as A 17. Particles of water, having no fire in and B, (FIG. VI. representing the profile of them, mutually attract each other. These a vessel of water) are more easily disengaged particles of water then, being attached to the than C and D, 'as each is held by contact three particles of a triangle of air, would, by with three only, whereas C and D are each their mutual attraction operating against the in contact with nine. When the surface of air's repulsion, shorten the sides and lessen the the water has the least motion, particles are triangle, whereby that portion of air made continually pushed into the situation repre- denser, would sink to the earth with its wasented by A and B.
ter, and not rise to the formation of a cloud. 8. Friction between a non-electric and an 18. But if every particle of water attaching electric per se will produce electrical fire; itself to air brings with it a particle of coninot by creating but collecting it; for it is mon fire, the repulsion of the air being assist equally diffused in our walls, floors, earth, and ed and strengthened by the fire, more than the whole mass of common matter. Thus the obstructed by the mutual attraction of the par
ticles of water, the triangle dilates, and that nearly filled with wine and electrified as the bottle. portion of air, becoming rarer and specifically ty be close shaved, and does not breath on the liquor: lighter, rises. April 29, 1719.
19. If the particles of water bring electri * Thunder-gusts are sudden storms of thunder and cal fire when they attach themselves to ai lightning, which are frequently of short duration, but soinetimes produce mischievous effects.
the repulsion between the particles of water