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TO PETER COLLINSON.
READ AT THE ROYAL SOCIETY, DECEMBER 21st, 1752.
Philadelphia, 19 October, 1752. SIR, As frequent mention is made in public papers from Europe, of the success of the Philadelphia experiment for drawing the electric fire from clouds by means of pointed rods of iron erected on high buildings, &c., it may be agreeable to the curious to be informed, that the same experiment has succeeded in Philadelphia, though made in a different and more easy manner, which is as follows.
Make a small cross of two light strips of cedar, the arms so long as to reach to the four corners of a large thin silk handkerchief when extended ; tie the corners of the handkerchief to the extremities of the cross, so you have the body of a kite; which, being properly accommodated with a tail, loop, and string, will rise in the air, like those made of paper; but this being of silk is fitter to bear the wet and wind of a thundergust without tearing. To the top of the upright stick of the cross is to be fixed a very sharp-pointed wire, rising a foot or more above the wood. To the end of the twine, next the hand, is to be tied a silk ribbon, and where the silk and twine join, a key may be fastened. This kite is to be raised when a thunder-gust appears to be coming on, and the person who holds the string must stand within a door or window, or under some cover, so that the silk ribbon may not be wet; and care must be taken that the twine does not touch the frame of the door or window. As soon as any of the thunder-clouds come over the kite, the pointed wire will draw the electric fire from them, and the kite, with all the twine, will be electrified, and the loose filaments of the twine will stand out every way, and be attracted by an approaching finger. And when the rain has wetted the kite and twine, so that it can conduct the electric fire freely, you will find it stream out plentifully from the key on the approach of your knuckle. At this key the phial may be charged; and from electric fire thus obtained, spirits may be kindled, and all the other electric experiments be performed, which are usually done by the help of a rubbed glass globe or tube, and thereby the sameness of the electric matter with that of lightning completely demonstrated.
Concerning the Electrical Experiments in England upon
READ AT THE ROYAL SOCIETY, DECEMBER 21st, 1752.
GENTLEMEN, After the communications, which we have received from several of our correspondents in different parts of the continent, acquainting us with the success of their experiments last summer, in endeavouring to extract the electricity from the atmosphere during a thunderstorm, in consequence of Mr. Franklin's hypothesis, it may be thought extraordinary, that no accounts have been yet laid before you, of our success here from the same experiments. That no want of attention, therefore, may be attributed to those here, who have been hitherto conversant in these inquiries, I thought proper to apprize you, that, though several members of the Royal Society, as well as myself, did, upon the first advices from France, prepare and set up the necessary apparatus for this purpose, we were defeated in our expectations, from the uncommon coolness and dampness of the air here, during the whole summer. We had only at London one thunder-storm, namely, on July 20th; and then the thunder was accompanied with rain, so that, by wetting the apparatus, the electricity was dissipated too soon to be perceived upon touching those parts of the apparatus which served to conduct it. This, I say, in general prevented our verifying Mr. Franklin's hypothesis ; but our worthy brother, Mr. Canton, was more fortunate. I take the liberty, therefore, of laying before you an extract of a letter, which I received from that gentleman, dated from Spital Square, July 21st, 1752.
A member of the Royal Society, and afterwards Sir William Wat
He was distinguished for his great acquirements in botany, and other natural sciences, and particularly for his experiments and discoveries in electricity. – EDITOR.
“I had yesterday, about five in the afternoon, an opportunity of trying Mr. Franklin's experiment of extracting the electrical fire from the clouds, and succeeded, by means of a tin tube, between three and four feet in length, fixed to the top of a glass one, of about eighteen inches. To the upper end of the tin tube, which was not so high as a stack of chimneys on the same house, I fastened three needles with some wire; and to the lower end was soldered a tin cover to keep the rain from the glass tube, which was set upright in a block of wood. I attended this apparatus as soon after the thunder began as possible, but did not find it in the least electrified, till between the third and fourth clap; when, applying my knuckle to the edge of the cover, I felt and heard an electrical spark; and,
approaching it a second time, I received the spark at the distance of about half an inch, and saw it distinctly. This I repeated four or five times in the space of a minute, but the sparks grew weaker and weaker; and in less than two minutes the tin tube did not appear to be electrified at all. The rain continued during the thunder, but was considerably abated at the time of making the experiment.” Thus far Mr. Canton.
Mr. Wilson likewise of the Society, to whom we are much obliged for the trouble he has taken in these pursuits, had an opportunity of verifying Mr. Franklin's hypothesis. He informed me, by a letter from near Chelmsford, in Essex, dated August 12th, 1752, that, on that day about noon, he perceived several electrical snaps, during, or rather at the end of a thunder-storm, from no other apparatus than an iron curtain-rod, one end of which he put into the neck of a glass phial, and held this phial in his hand. To the other end of the iron he fastened three needles with some silk. This phial, supporting the rod, he held in one hand, and drew snaps from the rod with a finger of his other. This experiment was not made upon any eminence, but in the garden of a gentleman, at whose house he
Dr. Bevis observed, at Mr. Cave's, at St. John's Gate, nearly the same phenomena as Mr. Canton, of which an account has been already laid before the public.
Trifling as the effects here mentioned are, when compared with those which we have received from Paris and Berlin, they are the only ones that the last summer here has produced ; and, as they were made by persons worthy of credit, they tend to establish the authenticity of those transmitted from our correspondents.
I flatter myself, that this short account of these matters will not be disagreeable to you; and am, With the most profound respect, Your most obedient humble servant,
TO JAMES BOW DOIN.
On the Mode of coating Electrical Jars.
Philadelphia, 12 April, 1753. SIR, I have shipped eighteen glass jars in casks well packed, on board Captain Branscombe for Boston ; six of them are for you, the rest I understand are for the College. Leaf tin, such as they use in silvering lookingglasses, is best- to coat them with ; they should be coated to within about four or five inches of the brim. Cut the tin into pieces of the form here represented, and they will comply better with the bellying of the glass; one piece only should be round to cover the bottom; the same shapes will serve the inside. I had not conveniency to coat them for you, and feared to trust anybody else, Mr. Kinnersley being abroad in the West Indies. To make the pieces comply the better, they may be cut in two where the cross lines are. They reach from the top to the edge of the round piece which covers the bottom. I place them in loose rims of scabboard, something like a small sieve, in which they stand very well. If you charge more than one or two together, pray take care how you expose your head to an accidental stroke; for, I can assure you from experience, one is