« ZurückWeiter »
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 we are indebted for the compass, and for spectacles, nor have even paper and printing, that record every thing else, been able to preserve 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 benefit mankind in that way, however well imagined, 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.
I am, &c.
TO M. DALIBARD, AT PARIS, ENCLOSED IN A LETTER
TO PETER COLLINSON.
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, DECEMBER 18TH, 1755.
Philadelphia, 29 June, 1755. SIR, You desire my opinion of Père Beccaria's Italian book.* I have read it with much pleasure, and think it one of the best pieces on the subject, that I have seen in any language. Yet, as to the article of Waterspouts, I am not at present of his sentiments; though I must own, with you, that he has handled it very ingeniously. Mr. Collinson has my opinion of whirlwinds and water-spouts at large, written some time since. I know not whether they will be published; if not, I will get them transcribed for your perusal.* It does not appear to me that Père Beccaria doubts of the absolute impermeability of glass in the sense I meant it; for the instances he gives of holes made through glass, by the electric stroke, are such as we have all experienced, and only show, that the electric fluid could not pass without making a hole. In the same manner we say, glass is impermeable to water, and yet a stream from a fire-engine will force through the strongest panes of a window. As to the effect of points in drawing the electric matter from the clouds, and thereby securing 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 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.
* This work is written conformably to Mr. Franklin's theory, upon artificial and natural electricity, which compose the two parts of it. It was
printed in Italian, at Turin, in quarto, 1753; between the two parts is a letter to the Abbé Nollet, in defence of Mr. Franklin's system. — J. Bevis.
* These papers will be found among the papers on Philosophical Subjects. Beccaria wrote a long letter to Franklin, dated at Turin, December 24th, 1757, giving an account of several experiments made by him in electricity, illustrative of Franklin's principles. The letter, written in Latin, is contained in the Philosophical Transactions, Vol. LI. p. 514; and also in the APPENDIX to this volume. - Editor.
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-cock. Near the bell was fixed an iron hammer to strike the hours; and from the tail of 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 knittingneedle. 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 abovementioned 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 aforementioned 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.
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.
5. Though the small wire was itself destroyed, yet it had conducted the lightning with safety to the building.
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 JOHN PRINGLE.*
On the Effects of Electricity in Paralytic Cases.
Craven Street, 21 December, 1757. SIR, In compliance with your request, I send you the following account of what I can at present recollect relating to the effects of electricity in paralytic cases, which have fallen under my observation.
Some years since, when the newspapers made mention of great cures performed in Italy and Germany by means of electricity, a number of paralytics were brought to me from different parts of Pennsylvania, and the neighbouring provinces, to be electrized, which I did for them at their request. My method was, to place the patient first in a chair, on an electric stool, and draw a number of large strong sparks from all parts of the affected limb or side. Then I fully charged two six gallon glass jars, each of which had about three square feet of surface coated; and I sent the united shock of these through the affected limb or limbs, repeating the stroke commonly three times each day. The first thing observed, was an immediate greater
Afterwards Sir John Pringle, and President of the Royal Society. - Editor.