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Your question, how I came first to think | cloud may occasion a neighbouring cloud to of proposing the experiment of drawing down draw into itself from others, an additional the lightning, in order to ascertain its sameness with the electric fluid, I cannot answer better than by giving you an extract from the minutes I used to keep of the experiments I made, with memorandums of such as I purposed to make, the reasons for making them, and the observations that arose upon them, from which minutes my letters were afterwards drawn. By this extract you will see that the thought was not so much" an out-of the-way one," but that it might have occurred to an electrician.

quantity, and, passing by it, leave it in a positive state. How these effects may be produced, you will easily conceive, on perusing and considering the experiments in the enclosed paper: and from them too it appears probable, that every change from positive to negative, and from negative to positive, that, during a thunder-gust, we see in the corkballs annexed to the apparatus, is not owing to the presence of clouds in the same state, but often to the absence of positive or negative clouds, that, having just passed, leave the rod in the opposite state.

"Nov. 7, 1749. Electrical fluid agrees with lightning in these particulars; 1. Giv- The knocking down of the six men was ing light. 2. Colour of the light. 3. Crooked performed with two of my large jars not fully direction. 4. Swift motion. 5. Being con- charged. I laid one end of my discharging ducted by metals. 6. Crack or noise in ex-rod upon the head of the first; he laid his ploding. 7. Subsisting in water or ice. 8. Rending bodies it passes through. 9. Destroying animals. 10. Melting metals. 11. Firing inflammable substances. 12. Sulphureous smell.-The electric fluid is attracted by points. We do not know whether this property is in lightning.-But since they agree in all the particulars wherein we can already compare them, is it not probable they agree likewise in this? Let the experiment be made."

hand upon the head of the second; the second his hand on the head of the third, and so to the last, who held, in his hand, the chain that was connected with the outside of the jars. When they were thus placed, I applied the other end of my rod to the prime conductor, and they all dropped together. When they got up, they all declared they had not felt any stroke, and wondered how they came to fall; nor did any of them either hear the crack, or see the light of it. You suppose it a dangerous experiment; but I had once suffered the same myself, receiving, by accident, an equal stroke through my head, that struck me down, without hurting me and I had seen a young woman who was about to be electrified through the feet (for some indisposition) receive a greater charge through the head, by inadvertently stooping forward to look at the placing of her feet, till her fore head (as she was very tall) came too near my prime conductor: she dropped, but instantly got up again, complaining of nothing. A person so struck, sinks down doubled, or folded together as it were, the joints losing their strength and stiffness at once, so that he drops on the spot where he stood, instantly, and there is no previous staggering, nor does he ever fall lengthwise. Too great a charge might, indeed, kill a man, but I have not yet seen any hurt done by it. It would certainly, as you observe, be the easiest of all deaths.

I wish I could give you any satisfaction in the article of clouds. I am still at a loss about the manner in which they become charged with electricity; no hypothesis I have yet formed perfectly satisfying me. Some time since, I heated very hot, a brass plate two feet square, and placed it on an electric stand. From the plate a wire extended horizontally four or five feet, and, at the end of it, hung, by linen threads, a pair of cork balls. I then repeatedly sprinkled water over the plate, that it might be raised from it in vapour, hoping that if the vapour either carried off the electricity of the plate, or left behind it that of the water, (one of which I supposed it must do, if, like the clouds, it became electrised itself, either positively or negatively) I should perceive and determine it by the separation of the balls, and by finding whether they were positive or negative; but no alteration was made at all, nor could I perceive that the steam was itself electrised, though I have The experiment you have heard so imperstill some suspicion that the steam was not fect an account of, is merely this: I electrifully examined, and I think the experiment fied a silver pint can, on an electric stand, should be repeated. Whether the first state and then lowered into it a cork ball, of about of electrised clouds is positive or negative, if an inch diameter, hanging by a silk string, I could find the cause of that, I should be at till the cork touched the bottom of the can. no loss about the other, for either is easily de- The cork was not attracted to the inside of the duced from the other, as one state is easily can as it would have been to the outside, and produced by the other. A strongly positive though it touched the bottom, yet when drawn cloud may drive out of a neighbouring cloud out, it was not found to be electrified by that much of its natural quantity of the electric touch, as it would have been by touching the fluid, and, passing by it, leave it in a negative outside. The fact is singular. You require state. In the same way, a strongly negative the reason; I do not know it. Perhaps you

any

compass,

and for spec

we are indebted for the
tacles, nor have even paper and printing,
that record every thing else, been able to pre-
serve with certainty the name and reputation
of their inventors. One would not, therefore,
of all faculties, or qualities of the mind, wish,
for a friend, or a child, that he should have
that of invention. For his attempts to bene-
fit mankind in that way, however well ima-
gined, if they do not succeed, expose him,
though very unjustly, to general ridicule and
contempt; and, if they do succeed, to envy,
robbery, and abuse. B. FRANKLIN.

Mons. Dalibard, Paris.

Beccaria's work on Electricity.-Sentiments of Franklin on pointed Rods, not fully understood in Europe.-Effect of Lightning on the Church of Newbury, in New England-Remarks on the subject.-Read at the Royal Society, Dec. 18, 1775.

may discover it, and then you will be so good as to communicate it to me.* I find a frank acknowledgment of one's ignorance is not only the easiest way to get rid of a difficulty, but the likeliest way to obtain information, and therefore I practise it: I think it an honest policy. Those who affect to be thought to know every thing, and so undertake to explain every thing, often remain long ignorant of many things that others could and would instruct them in, if they appeared less conceited. The treatment your friend has met with is so common, that no man who knows what the world is, and ever has been, should expect to escape it. There are every where a number of people, who being totally destitute of inventive faculty themselves, do not readily conceive that others may possess it: they think of inventions as of miracles; there might With be such formerly, but they are ceased. these, every one who offers a new invention is deemed a pretender: he had it from some PHILADELPHIA, June 29, 1755. other country, or from some book: a man of You desire my opinion of Père Beccaria's their own acquaintance; one who has no Italian book.* I have read it with much pleamore sense than themselves, could not possi- sure, and think it one of the best pieces on bly, in their opinion, have been the inventor the subject that I have seen in any language. of any thing. They are confirmed too, in Yet as to the article of water-spouts, I am not these sentiments, by frequent instances of pre- at present of his sentiments; though I must tensions to invention, which vanity is daily own with you, that he has handled it very inproducing. That vanity too, though an in- geniously. Mr. Collinson has my opinion of citement to invention, is, at the same time, whirlwinds and water-spouts at large, written the pest of inventors. Jealousy and envy desome time since. I know not whether they ny the merit or the novelty of your invention; will be published; if not, I will get them tranbut vanity, when the novelty and merit are scribed for your perusal. It does not appear established, claims it for its own. The smaller to me that Père Beccaria doubts of the absoyour invention is, the more mortification you lute impermeability of glass in the sense I receive in having the credit of it disputed meant it; for the instances he gives of holes with you by a rival, whom the jealousy and made through glass by the electric stroke are envy of others are ready to support against such as we have all experienced, and only you, at least so far as to make the point show that the electric fluid could not pass doubtful. It is not in itself of importance without making a hole. In the same manner enough for a dispute; no one would think we say, glass is impermeable to water, and your proofs and reasons worth their atten- yet a stream from a fire-engine will force tion: and yet, if you do not dispute the point, through the strongest panes of a window. As and demonstrate your right, you not only to the effect of points in drawing the electric lose the credit of being in that instance in-matter from clouds, and thereby securing genious, but you suffer the disgrace of not being ingenuous; not only of being a plagiary, but of being a plagiary for trifles. Had the invention been greater it would have disgraced you less; for men have not so contemptible an idea of him that robs for gold on the highway, as of him that can pick pockets for half-pence and farthings. Thus, through envy, jealousy, and the vanity of competitors for fame, the origin of many of the most extraordinary inventions, though produced within but a few centuries past, is involved in doubt and uncertainty. We scarce know to whom

* Dr. F. afterwards thought, that, possibly, the mu tual repulsion of the inner opposite sides of the electrised might prevent the accumulating of an electric atmosphere upon them, and occasion it to stand chiefly on the outside. But recommended it to the farther examination of the curious.

buildings, &c. which, you say, he seems to doubt, I must own I think he only speaks modestly and judiciously. I find I have been but partly understood in that matter. I have mentioned it in several of my letters, and except once, always in the alternative, viz. that pointed rods erected on buildings, and communicating with the moist earth, would either prevent a stroke, or, if not prevented, would conduct it, so as that the building should suffer no damage. Yet whenever my opinion is examined in Europe, nothing is considered but

*This work is written conformable to Dr. Franklin's theory, upon artificial and natural electricity, which compose the two parts of it. It was printed in Italian, at Turin, in 4to. 1753; between the two parts is a letter to the Abbe Nollet, in defence of Dr. Franklin's system. These papers will be found in a subsequent part of this volume.

the probability of those rods preventing a stroke or explosion, which is only a part of the use I proposed for them; and the other *part, their conducting a stroke, which they may happen not to prevent, seems to be totally forgotten, though of equal importance and advantage.

1. That lightning, in its passage through a building, will leave wood to pass as far as it can in metal, and not enter the wood again till the conductor of metal ceases.

And the same I have observed in other instances, as to walls of brick or stone.

2. The quantity of lightning that passed through this steeple must have been very great, by its effects on the lofty spire above the bell, and on the square tower all below the end of the clock pendulum.

3. Great as this quantity was, it was conducted by a small wire and a clock pendulum, without the least damage to the building so far as they extended.

4. The pendulum rod being of a sufficient thickness, conducted the lightning without damage to itself; but the small wire was utterly destroyed.

I thank you for communicating M. de Buffon's relation of the effect of lightning at Dijon, on the 7th of June last. In return, give me leave to relate an instance I lately saw of the same kind. Being in the town of Newbury, in New England, in November last, I was shown the effect of lightning on their church, which had been struck a few months before. The steeple was a square tower of wood reaching seventy feet up from the ground to the place where the bell hung, over which rose a taper spire, of wood likewise, reaching seventy feet higher, to the vane of the weather- 5. Though the small wire was itself decock. Near the bell was fixed an iron ham-stroyed, yet it had conducted the lightning mer to strike the hours: and from the tail of with safety to the building. the hammer a wire went down through a small gimlet-hole in the floor that the bell stood upon, and through a second floor in like manner; then horizontally under and near the plastered ceiling of that second floor, till it came near a plastered wall; then down by the side of that wall to a clock, which stood about twenty feet below the bell. The wire was not bigger than a common knitting-needle. The spire was split all to pieces by the lightning, and the parts flung in all directions over the square in which the church stood, so that nothing remained above the bell.

The lightning passed between the hammer and the clock in the above mentioned wire, without hurting either of the floors, or having any effect upon them (except making the gimlet-holes, through which the wire passed, a little bigger,) and without hurting the plastered wall, or any part of the building, so far as the aforesaid wire and the pendulum wire of the clock extended; which latter wire was about the thickness of a goose-quill. From the end of the pendulum, down quite to the ground, the building was exceedingly rent and damaged, and some stones in the foundation-wall torn out, and thrown to the distance of twenty or thirty feet. No part of the afore mentioned long small wire, between the clock and the hammer, could be found, except about two inches that hung to the tail of the hammer, and about as much that was fastened to the clock; the rest being exploded, and its particles dissipated in smoke and air, as gunpowder is by common fire, and had only left a black smutty track on the plastering, three or four inches broad, darkest in the middle, and fainter towards the edges, all along the ceiling, under which it passed, and down the wall. These were the effects and appearances; on which I would only make the few following remarks, viz.

VOL. II.... 2 P

6. And from the whole it seems probable, that if even such a small wire had been extended from the spindle of the vane to the earth, before the storm, no damage would have been done to the steeple by that stroke of lightning, though the wire itself had been destroyed.

To Peter Collinson.

PHILADELPHIA, Nov. 23, 1753.

DEAR FRIEND,-In my last, via Virginia, I promised to send you per next ship, a small philosophical packet: but now having got the materials (old letters and rough drafts) before me, I fear you will find it a great one. Nevertheless, as I am like to have a few days' leisure before this ship sails, which I may not have again in a long time, I shall transcribe the whole, and send it; for you will be under no necessity of reading it all at once, but may take it a little at a time, now and then of a winter evening. When you happen to have nothing else to do (if that ever happens) it may afford you some amusement.*

B. FRANKLIN.

*These letters and papers are a philosophical correspendence between Dr. Franklin and some of his American friends. Mr. Collinson communicated them to the Royal Society, where they were read at different meetings during the year 1756. But Dr. Franklin having particularly requested that they might not be printed, at that time an intention of revising them, and pursuing some of the inquiries farther; but finding that he was not likely to have sufficient leisure, he was at length induced, imperfect as they were, to permit their publication, as some of the hints they contain might possibly be useful to others in their philosophical researches. Note in Mr. Collinson's edition.

none of them were inserted in the transactions. He had

† As some of these papers are upon subjects not immediately connected with electricity, we have taken such papers from the order in which they were placed by Mr. Collinson, and transferred them to other parts of this edition.

Boston to Benjamin Franklin, concerning the crooked direction and the source of lightning, and the swiftness of the electric fire.

Extract of a letter from Mr. Bowdoin of The column, being thus acted upon, becomes more dense, and, being more dense repels the spark more strongly; its repellency being in proportion to its density: having acquired, by being condensed, a degree of repellency greater than its natural, it turns the spark out of its straight course; the neighbouring air, which must be less dense, and therefore has a smaller degree of repellency, giving it a more ready passage.

BOSTON, Dec. 21, 1751.

THE experiments Mr. K. has exhibited here, have been greatly pleasing to all sorts of people that have seen them; and I hope, by the time he returns to Philadelphia, his tour this way will turn to good account. His experiments are very curious, and I think prove most effectually your doctrine of electricity; that it is a real element, annexed to, and diffused among all bodies we are acquainted with; that it differs in nothing from lightning, the effects of both being similar, and their properties, so far as they are known, the same, &c.

mag

The spark, having taken a new direction, must now act on, or most strongly repel the column of air which lies in that direction, and consequently must condense that column in the same manner as the former, when the spark must again change its course, which course will be thus repeatedly changed, till the spark reaches the body that attracted it.

To this account one objection occurs; that as air is very fluid and elastic, and so endeavours to diffuse itself equally, the supposed accumulated air within the column aforesaid, would be immediately diffused among the contiguous air, and circulate to fill the space it was driven from and consequently that the said column, on the greater density of which the phenomenon is supposed to depend, would not repel the spark more strongly than the neighbouring air.

This might be an objection, if the electrical fire was as sluggish and inactive as air. Air takes a sensible time to diffuse itself equally,

as is manifest from winds which often blow for a considerable time together from the same point, and with a velocity even in the greatest storms, not exceeding, as it is said, sixty miles an hour: but the electric fire seems propagated instantaneously, taking up no perceptible time in going very great distances. It must then be an inconceivable short time in its progress from an electrified to an unelectrified body, which, in the present case, can be but a few is not sufficient for elasticity of the air to exert inches apart but this small portion of time itself, and therefore the column aforesaid must be in a denser state than its neighbouring air.

The remarkable effect of lightning on iron, lately discovered, in giving it the netic virtue, and the same effect produced on small needles by the electrical fire, is a further and convincing proof that they are both the same element; but, which is very unaccountable, Mr. K. tells me, it is necessary to produce this effect, that the direction of the needle and the electric fire should be north and south; from either to the other, and that just so far as they deviate therefrom, the magnetic power in the needle is less, till their direction being at right angles with the north and south, the effect entirely ceases. We made at Faneuil Hall, where was Mr. K.'s apparatus, several experiments, to give some small needles the magnetic virtue; previously examining, by putting them in water, on which they will be supported, whether or not they had any of that virtue; and I think we found all of them to have some small degree of it, their points turning to the north; we had nothing to do then but to invert the poles, which accordingly was done, by sending through them the charge of two large glass jars; the eye of the needle turning to the north, as the point before had done: that end of the needle which the fire is thrown upon, About the velocity of the electric fire more Mr. K. tells me always points to the north. is said below, which perhaps may more fully The electrical fire passing through air has obviate this objection. But let us have rethe same crooked direction as lightning.* course to experiments. Experiments will obThis appearance I endeavour to account for viate all objections, or confound the hypothethus: air is an electric per se, therefore there sis. The electric spark, if the foregoing be must be a mutual repulsion betwixt air and true, will pass through a vacuum in a right the electrical fire. A column or cylinder of line. To try this, let a wire be fixed perair, having the diameter of its base equal to the diameter of the electrical spark, intervenes that part of the body which the spark is taken from, and of the body it aims at. The spark acts upon this column, and is acted upon by it, more strongly than any other neighbouring portion of air.

* This is most easily observed in large strong sparks taken at some inches distance.

pendicularly on the plate of an air pump, having a leaden ball on its upper end; let another wire, passing through the top of a receiver, have on each end a leaden ball; let the leaden balls within the receiver, when put on the air pump, be within two or three inches of each other; the receiver being exhausted, the spark given from a charged phial to the upper wire will pass through rarified air, nearly approaching to a vacuum, to the

stroke, nor, which is more extraordinary, saw the light; which gave you just reason to conclude, that it was swifter than sound, than animal sensation, and even light itself. Now light (as astronomers have demonstrated) is about six minutes passing from the sun to the

lower wire, and I suppose in a right line, or nearly so; the small portion of air remaining in the receiver, which cannot be entirely exhausted, may possibly cause it to deviate a little, but perhaps not sensibly from a right line. The spark also might be made to pass through air greatly condensed, which per-earth; a distance, they say, of more than haps would give a still more crooked direction. I have not had opportunity to make any experiments of this sort, not knowing of an air-pump nearer than Cambridge, but you can easily make them. If these experiments answer, I think the crooked direction of light=ning will be also accounted for.

With respect to your letters on electricity; your hypothesis in particular for explaining the phenomena of lightning is very ingenious. That some clouds are highly charged with electrical fire, and that their communicating it to those that have less, to mountains and other eminences, makes it visible and audible, when it is denominated lightning and thunder, is highly probable; but that the sea, which you suppose the grand source of it, can collect it, I think admits of a doubt; for though the sea be composed of salt and water, an electric per se and non-electric, and though the friction of electrics per se and non-electrics, will collect that fire, yet it is only under certain circumstances which water will not admit. For it seems necessary, that the electrics per se and non-electrics rubbing one another, should be of such substances as will not adhere to, or incorporate with each other. Thus a glass or sulphur sphere turned in water, and so a friction between them, will not collect any fire; nor, I suppose, would a sphere of salt revolving in water: the water adhering to, or incorporating with those electrics per se. But granting that the friction between salt and water would collect the electrical fire; that fire, being so extremely subtle and active, would be immediately communicated, either to those lower parts of the sea from which it was drawn, and so only perform quick revolutions; or be communicated to the adjacent islands or continent, and so be diffused instantaneously through the general mass of the earth. I say instantaneously, for the greatest distances we can conceive within the limits of our globe, even that of the two most opposite points, it will take no sensible time in passing through; and therefore it seems a little difficult to conceive how there can be any accumulation of the electrical fire upon the surface of the sea, or how the vapours arising from the sea should have a greater share of that fire than other vapours. That the progress of the electrical fire is so amazingly swift, seems evident from an experiment you yourself (not out of choice) made, when two or three large glass jars were discharged through your body. You neither heard the crack, was sensible of the

eighty millions of miles. The greatest rectilinear distance within the compass of the earth is about eight thousand miles, equal to its diameter. Supposing then, that the velocity of the electric fire be the same as that of light, it will go through a space equal to the earth's diameter in about two sixtieths of the second of a minute. It seems inconceivable then, that it should be accumulated upon the sea, in its present state, which, as it is a non-electric, must give the fire an instantaneous passage to the neighbouring shores, and they convey it to the general mass of the earth. But such accumulation seems still more inconceivable when the electrical fire has but few feet depth of water to penetrate, to return to the place from whence it is supposed to be collected.

Your thoughts upon these remarks I shall receive with a great deal of pleasure. I take notice that in the printed copies of your letters, several things are wanting which are in the manuscript you sent me. I understand by your son, that you had writ, or was writing, a paper on the effect of the electrical fire on loadstones, needles, &c. which I would ask the favour of a copy of, as well as of any other papers on electricity, written since I had the manuscript, for which I repeat my obligations to you. J. BOWDOIN.

J. Bowdoin, Boston. Observations on the subjects of the preceding letter,

-Reasons for supposing the sea to be the grand source of Lightning.- Reasons for doubting this hypothesis.-Improvement in a globe for raising the Electric Fire.-Read at the Royal Society, May 27, 1756.

PHILADELPHIA, Jan. 24, 1752. I AM glad to learn, by your favour of the 21st past, that Mr. Kinnersley's lectures have been acceptable to the gentlemen of Boston, and are like to prove serviceable to himself.

I thank you for the countenance and encouragement you have so kindly afforded my fellow-citizen.

I send you enclosed an extract of a letter containing the substance of what I observed concerning the communication of magnetism to needles by electricity. The minutes I took at the time of the experiments are mislaid. I am very little acquainted with the nature of magnetism. Dr. Gawin Knight, inventor of the steel magnets, has wrote largely on that subject, but I have not yet had leisure to peruse his writings with the attention necessary to become master of his doctrine.

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