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that only a very small spark will be produced. In like manner, when lightning strikes a tree, a house, or a thunder rod, it is not because these objects are high, or in the neighbourhood of the cloud; but because they communicate with fome place below the furface of the ground, against which the impetus of the lightning is directed; and at that place the lightning would certainly arrive, though none of the above-mentioned objects had been interpofed. The fallacy of that kind of reafoning generally employed concerning the use of thunder rods, will now be apparent. Becaufe a point prefented to an electrified body in our experiments, always draws off the electricity in a filent manner; therefore Dr Franklin and his followers concluded, that a pointed conductor will do the fame thing to a thunder cloud, and thus effectually prevent any kind of danger from a stroke of lightning. Their reafoning on this subject, they think, is confirmed by the following fact among many others." Dr Franklin's houfe at Philadelphia was furnished with a rod extending 9 feet above the top of the chimney. To this rod was connected a wire of the thickness of a goofe quill, which defcended through the wall of the ftair cafe; where an interruption was made, fo that the ends of the wire, to each of which a little bell was fixed, were diftant from each other about fix inches; an infulated brass ball hanging between the two bells. The author was one night waked by loud cracks, proceeding from his apparatus in the ftair-cafe. He perceived, that the brafs-ball, inftead of vibrating as ufual between the bells, was repelled and kept at a distance from both; while the fire fometimes paffed in very large quick cracks directly from bell to bell; and fometimes in a continued denfe white ftream, feemingly as large as. his finger; by means of which the whole ftair-cafe was enlightened, as with fun-fhine, so that he could fee to pick up a pin. From the apparent quantity of electric matter, of which the cloud was thus evidently robbed, by means of the pointed rod (and of which a blunt conductor would not have deprived it), the author conceives, that a number of such conductors must confiderably leffen the quantity of electric fluid contained in any approaching cloud, before it comes fo near as to deliver its contents in a general ftroke." For this very reason, Mr B. Wilson and his followers, who conftitute the oppofite party, have determined that the ufe of pointed conductors is utterly unfafe. They fay, that in violent thunder ftorms the whole atmosphere is full of electricity; and that attempts to exhauft the vast quantity there collected, are like attempting to clear away an inundation with a fhovel, or to exhauft the atmofphere with a pair of bellows. They maintain, that though pointed bodies will effectually prevent the accumulation of electricity in any fubftance; yet if a non-electrified body is interpofed between a point and the conductor of an electrical machine, the point will be ftruck at the fame moment with the non-electrified body, and at a much greater diftance than that at which a knob would be ftruck. They affirm alfo, that, by means of this filent folicitation of the lightning, inflammable bodies, fuch as gun-powder, tinder, and Kunckel's phosphorus, may be fet on fire; and for

thefe laft facts they bring decifive experiments From all this, fay they, it is evident, that the ufe of pointed conductors is unfafe. They folicit a difcharge to the place where they are; and as they are unable to conduct the whole electricity in the atmosphere, it is impoffible for us to know whether the discharge they folicit may not be too great for our conductor to bear; and confequently all the mifchiefs arifing from thunder forms may be expected, with this additional and mortifying circumftance, that this very conductor hath probably folicited the fatal froke, when without it the cloud might have paffed harmless over our heads without ftriking at all. Here the reasoning of both parties feems equally wrong. They both proceed on this erroneous principle, That in thunder ftorms the conductor will always foli cit a difcharge, or that at fuch times all the elevated objects on the furface of the earth are drawing off the electricity of the atmosphere. But this cannot be the cafe, unless the electricity of the earth and of the atmosphere is of a dif ferent kind. Now it is demonftrable, that until this difference between the electricity of the atmosphere and of the furface of the earth ccafes, there cannot be a thunder form. When the atmosphere begins to be electrified either pofitively or negatively, the earth, by means of the inequalities and moisture of its furface, but especially by the vegetables which grow upon it, abforbs that electricity, and quickly becomes electrified in the fame manner with the atmosphere. This abforption, however, ceases in a very short time, because it cannot be continued without fetting in motion the whole of the electric matter contained in the earth itself. Alternate zones of pofitive and negative electricity will then begin to take place below the furface of the earth, for the reafons mentioned under ELECTRICITY, § 269, 270. Between the atmosphere and one of thefe zones, the stroke of the lightning always will be. Thus, fuppofing the atmofphere is pofitively electrified, the furface of the earth will, by means of trees, &c. quickly become pofitively electrified alfo; we fhail fuppofe to the depth of 10 feet. The electricity cannot penetrate farther on account of the refiftance of the electric matter in the bowels of the earth. At the depth of 10 feet from the surface, therefore, a zone of negatively electrified earth begins, and to this zone the electricity of the atmosphere is attracted; but to this it cannot get, without breaking through the pofitively electrified zone which lies uppermoft, and fhattering to pieces every bad conductor which comes in its way. We are fure, therefore, that in whatever places the outer zone of pofitively electrified earth is thinneft, there the lightning will ftrike, whether a conductor be prefent or not. If there is a conductor, either knobbed or sharppointed, the lightning will indeed infallibly strike it; but it would alfo have ftruck a house fituated on that spot without any conductor; and if the houfe had not been there, it would have ftruck the furface of the ground. Again, if we fuppofe the house with its conductor to ftand on a part of the ground where the pofitively electrified zone is very thick, the conductor will neither filently draw off the electricity, nor will the lightning ftrike it,

though

rough perhaps it may strike a much lower object, or even the the furface of the ground itself, at no great distance; the reafon of which undoubtedly Is, that there the zone of pofitively electrified earth is thinner than where the conductor was. The Franklinians therefore make their pointed conductors to be of too great confequence. To the houses on which they are fixed, no doubt, their importance is very great; but in exhaufting a thunder cloud of its electricity, their ufe muft appear trifling; and to infift on it, ridiculous. Innumerable objects, as trees, grafs, &c. are all confpiring to draw off the electricity, as well as the conductor, if it could be drawn off; but of effecting this there is an impoffibility, because they have the fame kind of electricity with the clouds themfelves. The conductor hath not even the power of attracting the lightning a few feet out of the direction which it would choofe of ittelf. Of this we have a moft decifive inftance in what happened to the magazine at Purfleet in Effex, on May 15, 1777. That houfe was furnifhed with a pointed conductor, raifed above the highest part of the building; nevertheless, about 6 P. M. a flash of lightning ftruck an iron cramp in the corner of the wall confiderably lower than the top of the conductor, and only 64 feet in a floping line diftant from the point.-This produced a long difpute with Mr Wilfon concerning the propriety of ufing pointed conductors; and, by the favour of his majesty, he was enabled to conftruct a more magnificent electrical apparatus than any private perfon could be supposed to erect at his own expenfe, and of which fome account is given under ELECTRICI TY, § 2O4. The only new experiments, how ever, which this apparatus produced, were the firing of gunpowder by the electric aura as it is called; and a particularly violent fhock which a perfon received when he held a small pointed wire in his hand, upon which the conductor was difcharged. The electrified furface of the conductor was 620 feet; and we can have but little idea of the ftrength of sparks from a conductor of this magnitude, fuppofing it properly electrified. Six turns of the wheel made the discharge felt through the whole body like the ftrong fhock of a Leyden vial; and nobody chose to make the experiment when the conductor had received a higher charge. A very strong shock was felt, when this conductor was discharged upon a pointed wire held in a perfon's hand, even though the wire communicated with the earth; which was not felt, or but very little, when a knobbed wire was made ufe of. To account for this difference may, perhaps, puzzle electricians; but with regard to the ufe of blunt or pointed thunder rods, both experiments feem quite inconclufive. Though a very great quanti ty of electric matter filently drawn off will fire gunpowder, this only proves that a pointed conductor ought not to pass through a barrel of gun powder; and if a perfon holding a pointed wire in his hand received a strong shock from Mr Wilfon's great conductor, it can thence only be inferred, that in the time of thunder nobody ought to hold the conductor in their hands; both which precautions common fenfe would dictate without any experiment. From the accident at Purfleet,

however, the difputants on both fides ought to have feen, that, with regard to lightning, neither points nor knobs can attract. Mr Willon furely had no reafon to condemn the pointed conductor for foliciting the flash of lightning, feeing it did not ftrike the point of the conductor, but a blunt cramp of iron; neither have the Franklinians any reafon to boaft of its effect in filently drawing off the electric matter, fince all its powers were nei ther able to prevent the flash, nor to turn it 46 feet out of its way. The fact is, the lightning was determined to enter the earth at the place where the board-house stands, or near it. The conductor fixed on the house offered the easiest communication; but 46 feet of air intervening between the point of the conductor and the place of explosion, the refiftance was lefs through the blunt cramp of iron, and a few bricks moiftened with rain-water, to the fide of the metalline conductor, than through the 46 feet of air to its point; for the former was the way in which the lightning actually paffed. Mr Wilfon and his followers feem alfo miftaken, in fuppofing that a pointed conductor can folicit a greater difcharge, than what would otherwife happen. Allowing the quantity of electricity in the atmosphere during the time of a thunder ftorm to be as great as they please to fuppofe; neverthelefs, it is impoffible that the air can part with all its electricity at once, on account of the difficulty with which the fluid moves in it. A pointed conductor, therefore, if it does any thing at all, can only folicit the partial difcharge which is to be made at any rate; and if none were to be made though the conductor was abfent, its prefence will not be able to effect any. An objection to the ufe of conductors, whether blunt or pointed, may be drawn from the accident which happened to the poors houfe at Heckingham, which was ftruck by lightning, though furnished with 8 pointed conductors; but from an accurate confideration of the manner in which the conductors were fituated, it appears that there was not a poffibility of their preventing any ftroke. See Philof. Tranf. Vol. LXXII. p. 361.

(10.) LIGHTNING, NEW SPECIES AND THEORY OF. In a late publication on the subject of elec. tricity by the E. of Stanhope (then Lord Mahon), we find a new kind of lightning mentioned, which he is of opinion may give a fatal stroke, even though the main explofion be at a confiderable diftance; a mile, for inftance, or more. This be calls the electrical returning stroke; and exemplifies it in the following manner, from fome experiments made with a very powerful electrical machine, the prime conductor of which (fix feet long, by one foot diameter) would generally, when the weather was favourable, ftrike into a brass ball connected with the earth, to the diftance of 18 inches or more. In the following account, this brafs ball, which we shall call A, is supposed to be conftantly placed at the friking distance; lo that the prime conductor, the inftant that it becomes fully charged, explodes into it. Ancther large conductor, which we fhall call the fecond condutor, is fufpended, in a perfectly infulated ftate, farther from the prime conductor than the ftriking distance, but within its electrical atmof phere; at the distance of fix feet, for inftance. A

perfon

person standing on an infulating ftool touches this fecond conductor very lightly with a finger of his right hand; while with a finger of his left hand, he communicates with the earth, by touching very lightly a second brass ball fixed at the top of a metallic ftand, on the floor, and which we fhall call B. While the prime conductor is receiving its electricity, fparks pass (at least if the diftance between the two conductors is not too great) from the 2d conductor to the infulated perfon's right hand; while similar and fimultaneous fparks pass out from the finger of his left hand into the ad metallic bail B, communicating with the earth. Thefe fparks are part of the natural quantity of electric matter belonging to the fecond conductor, and to the infulated perfon, driven from them into the earth, through the ball B, and its ftand, by the elaftic preffure or action of the electrical atmosphere of the prime conductor. The fecond conductor and the infulated perfon are hereby reduced to a negative state. At length, however, the prime conductor, having acquired its full charge, fuddenly strikes into the ball A of the first metallic ftand, placed for that purpose at the friking distance of 17 or 18 inches. The explofion being made, and the prime conductor fuddenly robbed of its electric atmosphere, its preffure or action on the fecond conductor, and on the infulated perfon, as fuddenly ceafes; and the latter inftantly feels a smart returning ftroke, though he has no direct or visible communication (except by the floor) either with the striking or fruck body, and is placed at the distance of five or fix feet from both of them. This returning ftroke is evidently occafioned by the fudden re-entrance of the electric fire naturally belonging to his body and to the second conductor, which had before been expelled from them by the action of the charged prime conductor upon them; and which returns to its former place the inftant that action of elaftic preffure ceases. The author fhows, that there can be no reason to fuppofe, that the electrical discharge from the prime conductor fhould in this experiment divide itself at the inftant of the explofion, and go different ways, fo as to ftrike the fecond conductor and infulated perfon in this manner, and at fuch a distance from it. When the ad conductor and the infulated perfon are placed in the denfeft part of the electrical atmosphere of the prime conductor, or just beyond the ftriking diftance, the effects are ftill more confiderable; the returning ftroke being extremely fevere and pungent, and appearing confiderably fharper than even the main ftroke itself, received directly from the prime conductor. This circumftance the author alleges as an unanswerable proof that the effect which he calls the returning froke, was not produced by the main stroke being any wife divided at the time of the explosion, fince no effect can ever be greater than the cause by which it is immediate ly produced. Having taken the returning ftroke eight or ten times one morning, he felt a confiderable degree of pain across his cheft during the. whole evening, and a difagreeable fenfation in his arms and wrists all the next day. We come now to the application of this experiment, and of the doctrine deduced from it, to what paffes in natural

ele@ricity, or during a thunder ftorm; in which there is reafon to expect fimilar effects, but on a larger fcale:-a scale so large indeed, according to the author's representation, that persons and animals may be destroyed, and particular parts of buildings may be confiderably damaged, by an electrical returning stroke, occafioned even by fome very diftant explofion from a thunder cloud, pof fibly at the distance of a mile or more. It is certainly eafy to conceive, that a charged extenfive thunder cloud must be productive of effects fimi lar to thofe produced by the author's prime con ductor. Like it, while it continues charged, it will, by the fuperinduced elastic electrical pressure of its atmosphere, to ufe the author's own expreffion, drive into the earth a part of the electric fluid naturally belonging to the bodies which are within the reach of its widely extended atmosphere; and which will therefore become negatively electrical. This portion too of their electric fire, as in the artificial experiments, will, on the explosion of the cloud, at a distance, and the ceffation of its action upon them, fuddenly return to them; fo as to pro duce an equilibrium and restore them to their natural state.

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(11.) LIGHTNING, OBJECTIONS TO LORD STANHOPE'S THEORY OF. To this theory, the authors of the Monthly Review have made feveral objections: "We cannot, however, agree (fay they) with the ingenious author, with refpect to the greatness of the effects, or of the dan ger to be apprehended from the returning stroke in this cafe; as we think his eftimate is grounded on an erroneous foundation. Since (fays he) the density of the electrical atmosphere of a thunder cloud is fo immenfe, when compared to the electrical denfity of the electrical atmosphere of any prime conductor, charged by means of any electrical apparatus whatfoever; and fince a returning ftrokes when produced by the fudden removal of even the weak elaftic electrical preffure of the electrical atmosphere of a charged prime conductor, may be extremely frong, as we have seen above; it is mathematically evident, that, when a returning ftroke comes to be produced by the fudden removal of the very ftrong elastic electrical preffure of the electrical atmosphere of a thunder cloud powerfully charged; the ftrength of fuch a returning Stroke muft be enormous." If indeed the quantity of electric fluid naturally contained in the body of a man, for inftance, were immense, or indefinite, the author's eftimate between the effects producible by a cloud, and those caused by a prime conductor, might be admitted. But furely an electrified cloud,-how great foever may be its extent, and the height of its charge when compared with the extent and charge of a prime con ductor-cannot expel from a man's body (or any other body) more than the natural quantity of electricity which it contains. On the sudden removal, therefore, of the preffure by which this natural quantity had been expelled, in confequence of the explofion of the cloud into the earth; no more (at the utmost) than his whole natural flock of electricity can re-enter his body. But we have no reafon to fuppofe that this quantity is fo great, as that its fudden re-entrance into his body should

deftroy

Heftroy or even injure him." The Reviewers urge feveral other arguments against the Earl's theory, for which we must refer to their work.

(12.) LIGHTNING, REPRESENTATIONS OF, or ARTIFICIAL LIGHTNING. Before Dr Franklin discovered the identity of electricity and lightning, many contrivances were invented to reprefent this terrifying phenomenon in miniature. The coruf cations of phofphorus.in warm weather, the accenfion of the vapour of spirit of wine evaporated in a clofe place, &c. were ufed in order to fupport the hypothefis which at that time prevailed; namely, that lightning was formed of fome ful phureous, nitrous, or other combuftible vapours, floating in long trains in the atmosphere, which by fome unaccountable means took fire, and pro duced all the destructive effects of that phenomenon. Thefe reprefentations, however, are now no more exhibited; and the only true artificial lightning is univerfally acknowledged to be the difcharge of electric matter from bodies in which it is artificially set in motion by electrical machines. See ELECTRICITỶ, Index.

that was killed, of the particular circumstances, They were both driving carts loaded with coals; and James Lauder, the perfon who was killed, had the charge of the foremost cart, and was fitting on the fore part of it. They had croffed the Tweed a few minutes before at a deep ford, and had almoft gained the highest part of an afcent of about 65 or 70 feet above the bed of the river, when he was ftunned with the report abovementioned, and faw his companion with the horfes and cart fall down. On running up to him, he found him quite dead, with his face livid, his clothes torn in pieces, and a great smell of burning about him. At the time of the explosion he was about 24 yards diftant from Lauder's cart, and had him full in view when he fell, but felt no fhock, neither did he perceive any flash or appearance of fire. At the time of the explosion his horfes turned round, and broke their harness. The horfes had fallen on their left fide, and their legs had made a deep impreffion on the duft; which, on lifting them up, thowed the exact form of each un leg, fo that every principle of life feemed to have (13.) LIGHTNING, SINGULAR ACCIDENT DU been extinguished at once, without the least strugRING A STORM OF. A late melancholy accident gle or convulfive motion. The hair was finged which happened in Scotland afforded Lord Stan- over the greatest part of their bodies, but was hope feveral additional arguments in favour of his hoft perceptible on their belly and legs. Their eyes fyftem. An account of this accident is given by were dull and opaque, as if they had been long Patrick Brydone, Efq. F. R. S. in the 77th vol dead, though Mr Brydone faw them in half an of the Phil. Tranf. It happened on the 19th of hour after the accident happened. The joints July 1785, near Coldstream on the Tweed: The were all fupple, and he could not obferve that any morning was fine, with the thermometer at 689; of the bones were broken or diffolved, as is faid to but about 11 A. M. the fky became obfcured with be fometimes the cafe with thofe who are killed clouds in the SE.: and betwixt 12 and 1 aftorm by lightning. The left shaft of the cart was broken, of thunder and lightning came on. This form and splinters had been thrown off in many places; was at a confiderable distance from Mr Brydone's particularly where the timber of the cart was con houfe, the intervals between the flash and crack nected by nails or cramps of iron. Many pieces of being from 25 to 30 feconds, fo that the place of the coals were thrown to a confiderable distance; explofion must have been betwixt 5 and 6 miles and fome of them had the appearance of being off: but while our author was observing the pro fome time on a fire. Lauder's hat was torn into grefs of the ftorm, he was fuddenly furprised with innumerable small pieces; fome part of his hair a loud report, neither preceded nor accompanied was strongly united to thofe which had compofed by any flash of lightning, which refembled the ex- the crown of it. About 44 feet behind each wheel plofion of a great number of muskets, in fuch of the cart, he obferved a circular hole of about quick fucceffion, that the air could fcarcely difcri- 20 inches diameter, the centre of which was exactminate the founds. On this the thunder and lightly in the track of each wheel. The earth was torn ning inftantly ceafed, the clouds began to feparate, and the sky foon recovered its ferenity. In a lit tte time Mr Brydone was informed, that a man with two horses had been killed by the thunder; and, on running out to the place, our author found the two horfes lying on the spot where they had been first ftryck, and still yoked to the cart. As the body of the man who was killed had been carried off, Mr Brydone had not an opportunity of examining it, but was informed by Mr Bell, minister of Coldftream, who saw it, that the fkin of the right thigh was much burnt and thrivelled: that there were many marks of the fame kind all over the body, but none on the legs: his clothes, particularly his fhirt, had a strong fmell of burning; and there was a zig-zag line of about an inch and a quarter broad, extending from the chin to the right thigh, and which feemed to have follow ed the direction of the buttons of his waistcoat. The body was buried in two days without any appearance of putrefaction. Mr Brydone was informed by another person who accompanied him

up as if by violent blows of a pick-ax; and the fmall ftones and duft were fcattered on each fide of the road. The tracks of the wheels were ftrongly marked in the duft, both before and behind thefe holes, but did not in the smallest degree appear on the spots themselves for upwards of a foot and a half. There were evident marks of fufion on the iron rings of the wheels; the furface of the iron, the whole breadth of the wheel, and for the length of about three inches was become bluish, had loft its polish and fmoothnefs, and was formed into drops which projected fenfibly, and had a roundifh form; but the wood did not appear any way injured by the heat which the iron must have con ceived. To determine whether these were made by the explosion which had torn up the ground, the cart was pushed back on the fame tracts which it had defcribed on the road; and the marks of fufion were found exactly to correfpond with the centres of the holes. They had made almost half a revolution after the explosion; which our author afcribes to the cart being pulled a little forward by

the

the fall of the horfes. Nothing remarkable was obferved on the oppofite part of the wheel. The broken ground had a smell fomething like that of ether; the foil itself was very dry and gravelly. The catastrophe was likewife obferved by a fhepherd, at the distance of about 200 or 300 yards from the spot. He faid, that he was looking at the two carts going up the bank when he heard the report, and faw the foremost man and horfes fall down; but obferved no lightning, nor the leaft appearance of fire, only he faw the duft rife about the place. There had been several flashes of lightning before that from the SE.; whereas the accident happened to the NW. of the place where he ftood. He was not fenfible of any shock. Our author next gives an account of feveral phenomena which happened the fame day, and which were evident ly connected with the explofion. A fhepherd attending his flock in the neighbourhood, obferved a lamb drop down; and faid, that he felt at the fame time as if fire had paffed over his face, though the lightning and claps of thunder were at a confiderable distance. He ran up to the creature immediately, but found it quite dead; on which he bled it with his knife, and the blood flowed free. ly. The earth was not torn up; nor did he obferve any duft rife, though he was only a few yards diftant. This happened about a quarter of an hour before Lauder was killed, and the place was only about 300 yards diftant. About an hour before the explosion, two men ftanding in the middle of the Tweed, fishing for falmon, were caught in a violent whirlwind, which felt fultry and hot, and almost prevented them from breathing. They could not reach the bank without much difficulty and fatigue; but the whirlwind lafted only a very fhort time, and was fucceeded by a perfect calm. A woman making hay, near the banks of the river, fell fuddenly to the ground, and called out that fhe had received a violent blow on the foot, and could not imagine from whence it came; and Mr Bell, the minifter above mentioned, when walk ing in his garden, a little before the accident hap. pened to Lauder, felt feveral times a tremor in the ground. The conclufion drawn from these facts by Brydone is, that at the time of the explosion the equilibrium between the earth and the atmof. phere feems to have been completely refted, as no more thunder was heard nor lightning obferved; the clouds were difpelled, and the atmofphere refumed the most perfect tranquillity; "But how this vaft quantity of electric matter (fays he) could be discharged from the one element to the other without any appearance of fire, I fhall not pretend to examine. From the whole it would appear, that the earth had acquired a great fuperabundance of electrical matter, which was every where endeavouring to fly off into the atmosphere. Perhaps it might be accounted for from the excef five dryness of the ground, and for many months the almoft total want of rain, which is probably the agent that nature employs in preferving the equilibrium between the two elements."

(14) LIGHTNING, STANHOPE'S EXPLANATION OF THE ABOVE ACCIDENT, BY A RETURNING STROKE OF. Earl Stanhope, whofe obfervations on this accident are published in the fame volume, endeavours to establish the following pofitions as VOL. XIII. PART I

facts. 1. That the man and horfes were not killed by any direct main ftroke of explofion from a thunder cloud either pofitively or negatively electrified. 2. They were not killed by any transmitted main stroke either pofitive or negative. 3. The mifchief was not done by any lateral explofon. Allthese are evidently true, at leaft with refpect to lightning at that time falling from the clouds; for all the lightning which had taken place before was at a great diftance. 4. They were not fuffocated by a fulphureous vapour or fmell, which frequently accompanies electricity. This could not account for the pieces of coal being thrown to a con. fiderable distance all round the cart, and for the fplinters of wood which were thrown off from the cart. 5. It might be imagined by fome that they were killed by the violent commotion of the at mosphere, occafioned by the vicinity of the electrical explosion, in a manner fimilar to that whereby fatal wounds fometimes have been known to have been given, by the air having been fuddenly difplaced by a cannon ball, in its paffage through the atmospherical fluid, though the cannon ball itself had evidently neither ftruck the perfon wounded nor grazed his clothes. The duft that rofe at the time of the explosion might be brought as an argument in favour of the opinion, that a fudden and violent commotion of the air did occafion the effects produced. But fuch an explanation would not account for the marks of fufion on the iron of the wheels, nor for the hair of the horses being finged; nor for the skin of Lauder's body having been burnt in feveral places. 6. From thefe different circumftances his lordfhip is of opinion, that the effects proceeded from electricity; and that no electrical fire did pass immediately, either from the clouds into the cart, or from the cart into the clouds. From the circular holes in the ground, of about 20 inches diameter, the refpective centres of which were exactly in the tract of each wheel, and the corresponding marks of fufion in the iron of the wheels, it is evident that the electrical fire did pass from the earth to the cart, or from the cart to the earth, through that part of the iron of the wheels which was in contact with the ground. From the splinters which had been thrown off in many places, particularly where the timber was connected by nails or cramps of iron, and from various other effects mentioned in Mr Brydone's account, it is evident, that there must have been a great commotion in the electrical fluid in all, or at least in different parts of the cart, and in the bodies of the man and horfes, although there were no lightning. 7. All thefe phenomena, his lordship argues, may be explained in a fatisfactory manner from the doctrine already laid down concerning the returning ftroke. Before entering upon the fubject of the main explosion, however, he takes notice of the other phenomena mentionin Mr Brydone's account. With regard to the cafe of the lamb, his lordship is of opinion, that it belongs to the moft fimple clafs of returning ftrokes, viz. that which happens at a place where there is neither thunder nor lightning near; and that it may be produced by the fudden removal of the elaftic electrical preffure of the electrical atmosphere of a fingle main cloud, as well as of an aflemblage of clouds. It appears (fays he) by Mr Gg

Brydone's

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