second experiment, must be in a much more and imbibed by the balls to supply the defidense part of the atmosphere of the tube, be- ciency; and that more plentifully at the apfore they will repel each other. At the approach of excited glass; or a body positively proach of an excited stick of wax to the balls, electrified, than before; whence the distance in the first experiment, the electrical fire is between the balls will be increased, as the supposed to come through the threads into the fluid surrounding them is augmented. And balls, and be condensed there, in its passage in general, whether by the approach or recess towards the wax; for, according to Mr. of any body; if the difference between the Franklin, excited glass emits the electrical density of the internal and external fluid be fluid, but excited wax receives it. increased or diminished; the repulsion of the balls will be increased or diminished accordingly.

EXPERIMENT VII.

Let the tin tube, with a pair of balls at one end, be placed three feet at least from any part of the room, and the air rendered very dry by means of a fire: electrify the apparatus to a considerable degree; then touch the tin tube with a finger, or any other conductor, and the balls will, notwithstanding, continue to repel each other; though not at so great a distance as before...

The air surrrounding the apparatus to the distance of two or three feet, is supposed to contain more or less of the electrical fire, than its common share, as the tin tube is electrified positively, or negatively: and when very dry, may not part with its overplus, or have its deficiency supplied so suddenly, as the tin; but may continue to be electrified, after that has been touched for a considerable time.

In the sixth experiment, part of the fluid | tively. And it is probable, that all bodies driven out of one tin tube enters the other; whatsoever may have the quantity they conwhich is found to be electrified positively, by tain of the electrical fluid increased or dimithe decreasing of the repulsion of its balls, at nished. The clouds, I have observed, by a the approach of excited glass. great number of experiments, to be some in a positive, and others in a negative state of electricity. For the cork balls, electrified by them, will sometimes close at the approach of excited glass; and at other times be separated to a greater distance. And this change I have known to happen five or six times in less than half an hour; the balls coming together each time, and remaining in contact a few seconds, before they repel each other again. It may likewise easily be discovered, by a charged phial, whether the electrical fire be drawn out of the apparatus by the negative cloud, or forced into it by a positive one: and by which soever it be electrified, should that cloud either part with its overplus, or have its deficiency supplied suddenly, the apparatus will lose its electricity: which is frequently observed to be the case, immediately after a flash of lightning. Yet when the air is very dry, the apparatus will continue to be electrified for ten minutes, or a quarter of an hour, after the clouds have passed the zenith; and Having made the Torricellian vacuum about towards the horizon. Rain, especially when sometimes till they appear more than half-way five feet long, after the manner described in the drops are large, generally brings down the Philosophical Transactions, vol. xlvii. P.the electrical fire; and hail, in summer, I be370, if the excited tube be brought within a lieve never fails. When the apparatus was small distance of it, a light will be seen through last electrified, it was by the fall of thawing more than half its length; which soon vanishes, if the tube be not brought nearer; but will snow, which happened so lately, as on the 12th of November; that being the twentyappear again, as that is moved farther off-sixth day, and sixty-first time it has been This may be repeated several times, without electrified, since it was first set up; which exciting the tube afresh. renheit's thermometer was but seven degrees was about the middle of May. And as Fahabove freezing, it is supposed the winter will not entirely put a stop to observations of this sort. At London no more than two thunder storms have happened during the whole summer; and the apparatus was sometimes so strongly electrified in one of them, that the bells, which have been frequently rung by the clouds, so loud as to be heard in every room of the house (the doors being open) were silenced by the almost constant stream of dense electrical fire, between each bell and the brass ball, which would not suffer it to strike.

EXPERIMENT VIII.

This experiment may be considered as a kind of ocular demonstration of the truth of Mr. Franklin's hypothesis; that when the electrical fluid is condensed on one side of thin glass, it will be repelled from the other, if it meets with no resistance. According to which, at the approach of the excited tube, the fire is supposed to be repelled from the inside of the glass surrounding the vacuum, and to be carried through the columns of mercury; as the tube is withdrawn, the fire is supposed to return.

EXPERIMENT IX.

but

Let an excited stick of wax, of two feet and a half in length, and about an inch in diamater, be held near its middle. Excite the glass tube, and draw it over one half of it; then, turning a little about its axis, let the tube be excited again, and drawn over the same half; and let this operation be repeated several times; then will that half destroy the repelling power of balls electrified by glass, and the other half will increase it.

I shall conclude this paper, already too long, with the following queries:

1. May not air, suddenly rarified, give electrical fire to, and air suddenly condensed, receive electrical fire from, clouds and vapours passing through it?

2. Is not the aurora borealis, the flashing of electrical fire from positive, towards negative clouds at a great distance, through the By this experiment it appears, that wax upper part of the atmosphere, where the realso may be electrified positively and nega-sistance is least?

Then withdraw the tube, and they will open again.

For now the electric matter in the prime conductor, returning to its equilibrium, or equal diffusion, in all parts of its substance, and the prime conductor having lost some of its natural quantity, the threads connected with it lose part of theirs, and so are elec trised negatively, and therefore repel each other, by Pr. III.

Approach the prime conductor with the tube near the same place as at first, and they will close again.

Because the part of their natural quantity of electric fluid, which they had lost, is now restored to them again, by the repulsion of the glass tube forcing that fluid to them from other parts of the prime conductor; so they are now again in their natural state.

Withdraw it, and they will open again. For what had been restored to them, is now taken from them again, flowing back into the prime conductor and leaving them once more electrised negatively.

Bring the excited tube under the threads,

and they will diverge more.

Because more of their natural quantity is driven from them into the prime conductor, and thereby their negative electricity increased.

EXPERIMENT III.

The prime conductor not being electrified, bring the excited tube under the tassel, and the threads will diverge.

did from the finger; which demonstrates the finger to be negatively electrised, as well as the lock of cotton so situated.

Turkey killed by Electricity.—Effect of a shock on the Operator in making the Experiment.

As Mr. Franklin, in a former letter to Mr.

Collinson, mentioned his intending to try the power of a very strong electrical shock upon a turkey, that gentleman accordingly has been so very obliging as to send an account of it, which is to the following purpose.

fowls, and found, that two large thin glass He made first several experiments on jars gilt, holding each about six gallons, were sufficient, when fully charged, to kill common hens outright; but the turkeys, though thrown into violent convulsions, and then lying as dead for some minutes, would recover in less than a quarter of an hour. However, having added three other such to the former two, though not fully charged, he killed a turkey of about ten pounds weight, and believes that they would have killed a much larger. He conceited, as himself says, that the birds killed in this manner eat uncommonly tender.

In making these experiments, he found, that a man could, without great detriment, bear a much greater shock than he had imagined: for he inadvertently received the stroke of when they were very near fully charged. It two of these jars through his arms and body, seemed to him an universal blow throughout the body, from head to foot, and was followed by a violent quick trembling in the trunk, which went off gradually, in a few seconds. It was some minutes before he could recollect his thoughts, so as to know what was the Keeping the tube in the same place with one matter; for he did not see the flash, though hand, attempt to touch the threads with the his eye was on the spot of the prime conductor, finger of the other hand, and they will re-from whence it struck the back of his hand; cede from the finger.

Part of their natural quantity is thereby driven out of them into the prime conductor, and they become negatively electrised, and therefore repel each other.

nor did he hear the crack, though the bystanders said it was a loud one; nor did he particularly feel the stroke on his hand, though he afterwards found it had raised a swelling His arms and the back of the neck felt somethere. of the bigness of half a pistol-bullet. what numbed the remainder of the evening, and his breast was sore for a week after,

Because the finger being plunged into the atmosphere of the glass tube, as well as the threads, part of its natural quantity is driven back through the hand and body, by that atmosphere, and the finger becomes, as well as the threads, negatively electrised, and so repels, and is repelled by them. To confirm this, hold a slender light lock of cotton, two as if it had been bruised. From this experior three inches long, near a prime conductor, ment may be seen the danger, even under that is electrified by a glass globe, or tube. the greatest caution, to the operator, when You will see the cotton stretch itself out to- making these experiments with large jars; wards the prime conductor. Attempt to touch for it is not to be doubted, but several of these it with the finger of the other hand, and it will fully charged would as certainly, by increas be repelled by the finger. Approach it with ing them, in proportion to the size, kill a man, a positively charged wire of a bottle, and it as they before did a turkey.

will fly to the wire. Bring it near a nega- N. B. The original of this letter, which tively charged wire of a bottle, it will recede was read at the Royal Society, has been misfrom that wire in the same manner that it laid.

Dr. Lining at Charleston.

to support himself chiefly by electricity. A Differences in the Qualities of the Glass.--Ac-strange project! But he was, as you observe, count of Domien, an Electrician and Travel-a very singular character. I was sorry the ler.-Conjectures respecting the pores of tubes did not get to the Havanna in time for Glass-Origin of the author's idea of draw him. If they are still in being, please to ing down Lightning.-No satisfactory Hypo- send for them, and accept of them. What thesis respecting the manner in which Clouds became of him afterwards I have never become electrified.-Six men knocked down at once by an electrical shock.-Reflections on the heard. He promised to write to me as often as he could on his journey, and as soon as he spirit of invention. should get home after finishing his tour. It is still in New Spain, as you imagine from is now seven years since he was here. If he that loose report, I suppose it must be that they confine him there, and prevent his writing but I think it more likely that he may

PHILADELPHIA, March 18, 1755.

I SEND you enclosed a paper containing some new experiments I have made, in pursuance of those by Mr. Canton that are printed with my last letters. I hope these, with my explanation of them, will afford you some

entertainment.*

be dead.

The questions you ask about the pores of know nothing of their nature; and supposiglass, I cannot answer otherwise, than that I tions, however ingenious, are often mere mistakes. My hypothesis, that they were smaller mit the passage of electricity, which could near the middle of the glass, too small to adpass through the surface till it came near the had written that letter, I did, in order to conmiddle, was certainly wrong; for soon after I have done before I wrote it) make an experifirm the hypothesis (which indeed I ought to

In answer to your several inquiries. The tubes and globes we use here, are chiefly made here. The glass has a greenish cast, but is clear and hard, and, I think, better for electrical experiments than the white glass of London, which is not so hard. There are certainly great differences in glass. A white globe I had made here some years since, would never, by any means, be excited. Two of my friends tried it, as well as myself, without success. At length, putting it on an electric stand, a chain from the prime conductor being in contact with it, I found it had ment. I ground away five sixths of the thickthe properties of a non-electric; for I couldness of the glass, from the side of one of my draw sparks from any part of it, though it was very clean and dry.

All I know of Domien, is, that by his own account he was a native of Transylvania, of Tartar descent, but a priest of the Greek church: he spoke and wrote Latin very readily and correctly. He set out from his own country with an intention of going round the world, as much as possible by land. He travelled through Germany, France, and Holland, to England. Resided some time at Oxford. From England he came to Maryland; thence went to New England; returned by land to Philadelphia; and from hence travelled through Maryland, Virginia, and North Carolina to you. He thought it might be of service to him in his travels to know something of electricity. I taught him the use of the tube; how to charge the Leyden phial, and some other experiments. He wrote to me from Charleston, that he had lived eight hundred miles upon electricity, it had been meat, drink, and clothing to him. His last letter to me was, I think, from Jamaica, desiring me to send the tubes you mention, to meet him at the Havanna, from whence he expected to get a passage to La Vera Cruz; designed travelling over land through Mexico to Acapulco; thence to get a passage to Manilla, and so through China, India, Persia, and Turkey, home to his own country; proposing

* See the preceding article, page 252, for the here referred to.

paper

phials, expecting that the supposed denser part being so removed, the electric fluid might come through the remainder of the glass, which I had imagined more open; but ed as well after the grinding as before. I am I found myself mistaken. The bottle chargnow, as much as ever, at a loss to know how or where the quantity of electric fluid, on the positive side of the glass, is disposed of.

As to the difference of conductors, there

is not only this, that some will conduct elecduct it fast enough to produce the shock; but tricity in small quantities, and yet do not coneven among those that will conduct a shock, there are some that do it better than others. Mr. Kinnersley has found, by a very good experiment, that when the charge of a bottle hath an opportunity of passing two ways, i. e. straight through a trough of water ten feet long, and six inches square; or round about the wire, and not through the water, though through twenty feet of wire, it passes through that is the shortest course; the wire being the better conductor. When the wire is taken away, it passes through the water, as may be felt by a hand plunged in the water; but it cannot be felt in the water when the wire is used at the same time. Thus, though a small phial containing water will give a of mercury will give one much stronger, the smart shock, one containing the same quantity mercury being the better conductor; while one containing oil only, will scarce give any shock at all.