XXII. New experiments in electricity: In a letter from Mr. Ebenezer Kinnersley, to Benjamin Franklin, LL. D. F. R. S. C 8 4 ] X X II. N e w Experiments in : a L e tte r fr o m M r . Ebenezer Kinnerfley, to Benjamin Franklin, L L . . F. R t S . Read Nov. 18, 1762, March 24, and April 14, 1763. S I R , Philadelphia, Mar. 12, 1761. A V I N G lately made the following experi­ ments, I very chearfully communicate them , in hopes of giving you fome degree of pleafure, and exciting you to further explore your favourite, but not quite exhaufted, fubjedt, E l e c t r i c i t y . 1 - 1 E X P . I. I placed myfelf on an eledtric ftand, and, being well eledtrifed, threw my hat to an uneledtrifed per- fon, at a confiderable diftance, on another ftand, and found, that the hat carried fome o f the electrici­ ty with it; for, upon going immediately to the per- ion, who received it, and holding a flaxen thread near him , I perceived he was eledtrifed fufficiently to at- tradt the thread. E X P . II. I then fufpended, by filk, a broad plate o f metal, and eledtrifed fome boiling water under it, at about four feet diftance, expedting that the vapour, which afcended plentifully to the plate, would, upon the principle of the foregoing experiment, carry up fome o f the eledtricity with i t ; but was at length fully con­ vinced, by feveral repeated trials, that it left all its fhare D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 [ 8 5 3 fhare thereof behind. T his I know not how to ac­ count f o r ; but does it not leem to corroborate your hypothecs, that the vapors, of which the clouds are formed, leave their (hare of electricity behind in the common flock, and afcend in a negative flate ? E X P . III. I put boiling water into a coated Florence flailc, and found that the heat fo enlarged the pores of the glafs, that it could not be charged. T h e electricity palled thro* as readily, to all appearance, as thro* m e ta l; the charge of a three-pint bottle went freely thro* without injuring the flafk in the leafl. W h e n it became almofl cold, I could charge it as ufual. W ould not this experiment convince the Abbe Nollet o f his egregious miflake ? For, while the electricity went fairly thro’ the glafs, as he contends it always does, the glafs could not be charged at all. E X P . IV. I took a flender piece of cedar, about eighteen inches long, fixed a brafs cap in the middle, thruft a pin, horizontally and at right angles, thro* each end, (the points in contrary directions) and hung it, nicely balanced like the needle of a compafs, on a pin, about fix inches long, fixed in the center o f an eleCtric hand. T h en eleCtrifing the ftand, I had the pleaf ure of feeing what I expected; the wooden nee­ dle turned round, carrying the pins with their heads foremofl. I then eleCtrifed the ftand negatively, ex­ pecting the needle to turn the contrary w ay; but was extremely difappointed, for it went ftill the fame way as before. 5 W hen D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 W h en the fland was eleCtrifed pofitively, I fup- pofe, that the natural quantity o f electricity in the air being increafed on one tide, by what ifilied from the points, the needle was attracted by the leffer quantity on the other fide. W h e n eleCtrifed nega­ tively, I fuppofe, that the natural quantity o f electri­ city in the air was diminished near the po in ts; in confequence whereof, the equilibrium being destroyed, the needle was attracted by the greater quantity on the oppofite fide. T h e doCtrine o f repulfion in eleCtrifed bodies, I begin to be fomewhat doubtful of. I think all the phenom ena, on which it is founded, may be well enough accounted for without it. W ill not cork balls, eleCtrifed negatively, feparate as far as when eleCtrifed pofitively ? A nd may not their feparation, in both cafes, be accounted for upon the fame prin­ ciple ; namely, the mutual attraction of the natural quantity in the air, and that which is denfer, or rarer in the cork ball ? It being one of the ettabliShed laws o f this fluid, that quantities of different denfities Shall mutually attract each other, in order to refiore the equilibrium. I can fee no reafon to conclude, that the air has not its Share o f the common flock of eieCtricity as well as glafs, and, perhaps, all other eieCtrics per fe. For tho’ the air will admit bodies to be eleCtrifed in it either pofitively or negatively, and will not readily carry off the redundancy in the one cafe, or fupply the deficiency in the other $ [ 85 ] E X P . D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 [ 87 ] E X P . V. Yet let a perfon in the negative ftate, out o f doors in the dark, when the air is dry, hold, with his arm extended, a long fharp needle, pointing upwards; and he will foon be convinced, that ele&ricity may be drawn out of the air; not very plentifully, for, being a bad conductor, it feems loth to part with i t ; but yet fome will evidently be collected. T h e air near the perlon’s body, having lefs than its natural quan­ tity, will have none to fpare ; but, his arm being ex­ tended as above, fome will be collected from the re­ moter air, and will appear luminous as it converges to the point of the needle. L et a perfon eleCtrifed negatively prefent the point o f a needle, horizontally, to a cork ball fufpended by filk, and the ball will be attracted towards the point, till it has parted with fo m uch o f its natural quantity of electricity as to be in the negative ftate, in the fame degree with the perfon who holds the needle : then it will recede from the p o in t; being, as I luppofe, attracted the contrary way by the elec­ tricity of greater denlity in the air behind it. But, as this opinion feems to deviate from eledtrical ortho­ doxy, I lhould be glad to fee thefe phenom ena bet­ ter accounted for by your fuperior and more pene­ trating genius. W hether the ele&ricity in the air, in clear dry weather, be of the fame denfity at the height o f two * or three hundred yards, as near the furface o f the earth, may be fatisfadlorily determined by your old experiment o f the kite. E X P . D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 E X P . VI. T h e twine fhould have, through-out, a very fmall wire in i t ; and the ends of the wire, where the fe- veral lengths are united, ought to be tied down with a waxed thread to prevent their aCting in the manner o f points. I have tried the experiment twice, when the air was as dry as we ever have it, and fo clear that not a cloud could be feen ; and found the twine each time, in a fmall degree eleCtrifed pofitively. T h e kite had three metalline points fixed to i t ; one on the top, and one on each fide. T h a t the twine was eleCtrifed, appeared by the feparating o f two fmall cork balls fufpended on the twine by fine flaxen threads, juft above where the filk was tied to it, and fheltered from the wind. T h a t the twine was elec- trifed pofitively, was proved by applying to it the wire o f a charged bottle; which caufed the balls to feparate further, without firfl coming nearer together. T his experiment fhewed, that the electricity in the air, at thofe times, was denfer above than below. But that cannot be always the cafe; for you know we have frequently found the thunder clouds in the ne­ gative ftate, attracting electricity from the earth. W h ich ftate it is probable they are always in when firft formed, and till they have received a fufficient fupply. H ow they come afterwards, towards the latter end o f the guff, to be in the pofitive ftate, which is fometimes the cafe, is a fubjeCt for further enquiry. After the above experiments with the wooden needle, I formed a crofs of two pieces of wood, o f equal [ 88 ] D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 equal length, interfedfing each other at right angles in the m iddle; hung it, horizontally, on a central pin, and fet a light horfe, with his rider, upon each extrem ity; whereupon, the whole being nicely bal­ a n c ed , and each courier urged on by an eledtrifed point, inilead of a pair of fpurs, I was entertained with an eledtrical horfe-rrace. I have contrived an eledlrical air thermometer, 'and made feveral experiments with it, that have afforded m e much fatisfadtion and pleafure. It is extremely fenfible of any alteration in the ftate of the included air, and fully determines that controverted point, w hether there be any heat in the eledlric fire. By the Plate [ T a b . IV.] and the following defcription, you will readily apprehend the conftrudtion of it. A. B. is a glafs tube about eleven inches long, and pne inch diameter in the bore. It has a brafs ferii ce­ m ented on each end, with a top and bottom part, C and D to be fcrewed on, air-tight, and taken off at pleafure. In the center o f the bottom part D , is a male fcrew, which goes into a brafs nut in the ma­ hogany pedeftal E . T h e wires F and G are for the eledtric fire to pafs through, darting from one to the other. T h e wire G extends through the pedeftal to H ; and may be raifed or lowered by means o f a male fcrew on it. T h e wire F may be taken out, and the hook I be fcrewed into the place of it. K is a glafs tube with a fmall bore, open at both ends, cemented in the brafs tube L, which fcrews into the top part C. T h e lower end of the tube K is immerfed in wa­ ter, coloured with cocbeneal, at the bottom o f the tube A B. ( I ufed at firft coloured fpirits of w ine; but, in one o f the experiments I made, it took fire.) V o l. L IIL O O n [ 89 ] D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 [ 9 0 ] On the top of the tube K is cemented, for ornament, a brafs feril, with a head fcrewed on it, which has a fmall air hole thro' its fide at . T h e wire is a fmall round fpring, that embraces the tube K fo as to flay wherever it is placed. T h e weight M is to keep ftrait whatever may be fufpended in the tube A B. on the hook I. Air muft be blown thro’ the tube K into the tube A B, ’till enough is intruded to raife, by its elaftic force, a column o f the coloured water, in the tube K up to r, or thereabouts} and then, the gage wire b being flipt down to the top of the column, the therm om eter is ready for ufe; E X P . V II. I fet the therm om eter on an eledtric ftand, with the chain N fixed to the prime condudfor, and kept it well eledtrifed a confiderable time} but this produced no fenfible effedt. W hich fliews, that the eledtric fire, when in a ftate of reft, has no more heat than the air and other matter wherein it refides. E X P . V III. W h en the wires F and G are in contadt, a large charge of eledtricity fent thro’ them , even th a t o f m y cafe of five and thirty bottles, containing above thirty fquare feet of coated glafs, will produce no rarefadtion of the air included in the tube A B. W hich fliews, that the wires are not heated by the fires pafling thro’ them. E X P . IX . W h en the wires are about two inches apart, the charge o f a three pint bottle, darting from one to the D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 C ? « ] th e other, rarefies the air very evidently. W hich {hews, I think, that the eledlric fire m ull produce heat in itfelf, as well as in the air, by it's rapid m o­ tion. T h e charge o f one o f my glafs jars, which will contain about five gallons and a half, wine meafure, darting from wire to wire, will, by the diflurbance it gives the air in the explofion repelling it in all di­ rections, raile the column in the tube K up to , or thereabouts; and the charge o f the above-mentioned caie of bottles will raife it to the top of the tube. Upon the air’s coalefcing, the column, by its gravity, inflantly fubfides till it is in equilibrio with the rarefied a ir ; it then gradually defcends, as the air cools, and fettles where it flood before. By carefully obferving at what height above the gage-wire b the defcending column firfl flops, the degree o f rarefaction is difco- vered; which, in great explofions, is very confiderable. E X P . X . I hung in the thermometer, upon the hook I , fucceflively, a flrip o f wet writing paper, a wet flax­ en and woolen thread, a blade of green grafs, a fila­ m ent of green wood, a fine filver thread, a very fmall brafs wire, and a flrip o f gilt paper; and found that the charge of the glafs jar, pafllng thro’ each of thefe, efpecially the daft, produced heat enough to rarify the air very perceptibly. T h e charge of the cafe of bot­ tles fent thro’ the brafs wire confumed great part of it into fmoke. T h e thermometer appeared quite opaque with it. O 2 E X P . D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 E X P . XL I then fu (pended, out o f the thermometer, apiece o f brafs wire, not quite fo fmali as the former, about twenty four inches long, with a pound weight at the lower e n d ; and, by fending the charge of the cafe o f bottles thro’ it, difeovered a new method o f wire­ drawing. T h e wire was red hot, the whole length well anealed, and above an inch longer than before. A fecond charge melted i t ; it parted near the middle, and meafured, when the ends were put together, four inches longer than at firft. T his experiment I re­ m em ber you propofed to me, as worth trying, before you left Philadelphia; in order to find, whether the electricity, in palling thro’ the wire, would fo relax the cohefion of its conftituent particles, as that the weight m ight produce a feparation; but neither o f us had the leaft fufpicion, that any heat would be produced. [ 92 J E X P . X II. T h a t I m ight have no doubt o f the wire’s being hot as well as red, I repeated the experiment on another piece of the fame wire, encompalled with a goofe- quill filled with loofe grains of gun-pow der; w hich took fire as readily, as if it had been touched with a read hot poker. Alfo tinder, tied to another piece o f the wire, kindled by it. I tried a wire about twice as big, but could produce no fuch effeCls w ith that. Hence it appears, that the eleCtric fire, tho’ it has no fenfible heat when in a ftate o f reft, will, by its violent D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 C 93 3 violent motion, and the refiflance it meets with, pro­ duce heat in other bodies, when palling thro’ them , provided they be fmall enough. A large quantity will pals thro' a large wire without producing any fenfibie h e a t; when the fame quantity palling thro’ a very fmall one, being there confined to a narrower paffage, the particles crowding clofer together, and meeting with greater refiflance, will make it red hot, and even melt it. Hence lightning does not melt metal by a cold fu- fion, as we formerly fuppofed. But when it paffes thro’ the blade of a fword, if the quantity be not ve­ ry great, it may heat the point fo as to melt it, while the broadefl and thickefl part may not be fenfibly warmer than before. And when trees or houfes are fet on fire by the dreadful quantity, which a cloud, or the earth fome- times difcharges, muff not the heat, by which the wood is firfl kindled, be generated by the lightning’s violent motion thro’ the refilling combuflible m at­ ter ? I f lightning, by its rapid motion, produces heat in itfelf as well as in other bodies, (and that it does, I think, is evident from fome of the foregoing experi­ ments made with the thermometer) then its fometimes fingeing the hair of animals killed by it may eafily be accounted for. And the reafon of its not always do­ ing lb may, perhaps, be th is : the quantity, tho’ fuf- ficient to kill a large animal, may, fometimes, not be great enough, or not have met w ith refiflance enough, to become by its motion burning hot. W e find, that dwelling houfes, ftruck with lightn­ ing, are feldom fet on fire by i t ; but when it pafles thro* 4 D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 thro’ barns with hay or ftraw in them , or ftore-houfes containing large quantities of hemp, or fuch like m at­ ter, they feldom, if ever, efcape a conflagration. W hich may, perhaps, be owing to fuch combuftibles being apt to kindle with lefs degree o f heat than is neceflary to kindle wood. W e had four houfes in this city, and a veflel at one o f the wharfs, ftruck, and damaged, by lightning laft fummer. One o f the houfes was ftruck twice in the fame ftorm. But I have the pleafure to inform you, that your method o f preventing fuch terrible difafters, has, by a fadt, which had like to have ef- caped our knowledge, given a very convincing proof o f its great utility, and is now in higher repute with us than ever. Hearing, a few days ago, that M r. W illiam W eft, m erchant in this city, fufpedted, that the lightning, in one o f the thunder-ftorms laft fummer, had pafled through the iron condudtor, which he had provided for the fecurity o f his houfe, I waited on him , to en­ quire what ground he m ight have for fuch fufpicion. M r. W eft informed me, that his family and neigh­ bours were all ftunned with a very terrible exploflon, and that the flafh and crack were feen and heard at the fame inftant. W hence he concluded, that the lightning m uft have been very n ear; and, as no houfe in the neighbourhood had fuffered by it, that it m uft have pafled through his conductor. M r. W hite, his clerk, told me, that he was fitting at the time by a window, about two feet from the condudtor, leaning againft the brick wall, with which it was in contadt $ and that he felt a fmart fenfation, like an eledtric (hock, in that part of his body, which touched the wall. [ 94 ] D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 [ 95 ] M r. W eft further informed me, that a perfon o f un­ doubted veracity allured him , that, being in the door o f an oppolite houfe on the other fide of W ater-Street (which you know is but narrow) he faw the lightning diffufed over the pavement, which was then very wet with rain, to the diftance o f two or three yards from the foot o f the conductor. And that another perfon o f very good credit told him , that he, being a few doors off, on the other lide o f the ftreet, faw the lightning above, darting in fuch direction, that it ap­ peared to him to be diredly over that pointed rod. Upon receiving this information, and being delirous o f further fatisfadion, there being no traces of the lightning to be difcovered in the condudor, as far as * we could examine it below, I propofed to M r. W eft our going to the top of the houfe to examine the pointed ro d ; alluring him , that, if the lightning had paffed thro’ it, the point muft have been melted -y and, to our great fatisfadion, we found it fo. T his iron rod extended in height about nine feet and a half above a ftack o f chimnies, to which it was fixed (but I fuppofe, three or four feet would have been iuftici- ent). It was fomewhat more than half an inch dia­ meter, in the thickeft part, and tapering to the upper end. T h e condudor, from the lower end of it to the earth, conlifted of fquare iron nail rods, not much above a quarter of an inch thick, conneded together by interlinking joints. It extended down the cedar roof to the eaves, and from thence down the wall of the houfe, four ftory and a half, to the pavement in W ater-Street being faftened to the wall, in leveral places,, by fmall iron hooks. T h e lower end wa$ fixed*. D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 [ 9 6 ] fixed to a ring in the top of an iron flake, that was driven about four or five feet into the ground. T h e above mentioned iron rod had a hole in the top of it, about two inches deep, wherein was inferted a brafs wire, about two lines thick, and, w hen firfl put there, about ten inches long, terminating in a very acute point; but now its whole length was no more than feyen inches and a half, and the top very blunt. Some o f the metal appears to be m illing; the flenderefl part of the wire being, as I fufpedt, confumed into fmoke. But fome of it, where the wire was a little thicker, being only melted by the lightning, funk down, while in a fluid flate, and formed a rough ir­ regular cap, lower on one fide than the other, round the upper end o f w hat remained, and became inti­ mately united therewith. T his was all the damage, that M r. W e ll fullained by a terrible flroke o f lightning. A m oll convincing proof of the great utility of this m ethod o f prevent­ ing its dreadful effects. Surely it will now be thought as expedient to provide conductors for the lightning as for the rain. M r. W eft was fo good as to make me a prefent of •the melted w ire ; which I keep as a great curiofity, and long for the pleafure of fhewing it to you. In the mean time, I beg your acceptance of the bell repre- fentation I can give of it; which you will find by the fide o f the thermometer, drawn in its full dim en- fions as it now appears. T h e dotted lines above are intended to fhew the form of the wire before the light­ ning melted it. A nd now, Sir, I moft heartily congratulate you on the piealure you m ull have in finding your great and well D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 C 97 ] well-grounded expectations fo far fulfilled. May this method of fecurity from the deftruCtive violence of one of the mofl: awful powers of nature meet with fuch further fuccefs, as to induce every good and grate­ ful heart to blefs God for the important difcovery. M ay the benefit thereof be diffufed over the whole globe. May it extend to the latefl pofterity of man­ k in d ; and make the name of F r a n k l in , like that of N e w t o n , immortal I am, Sir, with fincere refpedl, your mofl: obedient, and mofl: humble fervant, Ebenezer Kinnerfley. X X III. Obfervations in and on a fhunder-ftorm : I n a L etter from M r. T or- bern Bergman, to M r . Benjamin Wilfon, F. R. S. Acad. Reg. Upfal. Soc. Ampliflime atque Celeberrime Domine, Read April 14, T N epiftolis recentiflimis, quibus me 1763 A honorafti, experimenta domini Dela* val circa eleCtricitatem cryflalli Iflandicas commemo- ras. Pluries haecce tentamina iteravi, fed conflan- ter eventu prorfus contrario. Scilicet in hunc finem varia hujus cryftalli frufla frigori 12 graduum expofui, V ol. L III. P in D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 .Plzila.r.TnmJ. VolL.Zlf. .TAB. Vp 8,j. . .t Jlij ",le Jr . D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1