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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 III.

Let a tin tube, of four or five feet in length, and about two inches in diameter, be insulated by silk; and from one end of it let the cork-balls be suspended by linen threads. Electrify it, by bringing the excited glass tube near the other end, so as that the balls may stand an inch and a half, or two inches apart: then, at the approach of the excited tube, they will by degrees, lose their repelling power, and come into contact; and as the tube is brought still nearer, they will separate again to as great a distance as before: in the return of the tube they will approach each other till they touch, and then repel as at first. If the tin tube be electrified by wax, or the wire of a charged phial, the balls will be affected in the same manner at the approach of excited wax, or the wire of the phial.

EXPERIMENT IV.

Electrify the cork-balls as in the last experiment by glass, and at the approach of an excited stick of wax their repulsion will be increased. The effect will be the same, if the excited glass be brought towards them, when they have been electrified by wax.

The bringing the excited glass to the end, or edge of the tin tube, in the third experiment, is supposed to electrify it positively, or to add to the electrical fire it before contained; and therefore some will be running off through the balls, and they will repel each other. But at the approach of excited glass, which likewise emits the electrical fluid, the discharge of it from the balls will be diminished; or part will be driven back, by a force acting in a contrary direction: and they will come nearer together. If the tube be held at such a distance from the balls, that the excess of the density of the fluid round about them, above the common quantity in air, be equal to the excess of the density of that within them, above the common quantity contained in cork; their repulsion will be quite destroyed. But if the tube be brought nearer; the fluid without being more dense than within the balls, it will be attracted by them, and they will recede from each other again.

When the apparatus has lost part of its natural share of this fluid, by the approach of excited wax to one end of it, or is electrified negatively; the electrical fire is attracted

EXPERIMENT V.

When the insulated tin tube is not electri

fied, bring the excited glass tube towards the middle of it, so as to be nearly at right angles with it, and the balls at the end will repel each other; and the more so, as the excited tube is brought nearer. When it has been held a few seconds, at the distance of about six inches, withdraw it, and the balls will approach each other till they touch; and then separating again, as the tube is moved farther off, will continue to repel when it is taken quite away. And this repulsion between the balls will be increased by the approach of excited glass, but diminished by excited wax; just as if the apparatus had been electrified by wax, after the manner described in the third experiment.

EXPERIMENT VI.

Insulate two tin tubes, distinguished by A and B, so as to be in a line with each other, and about half an inch apart; and at the remote end of each, let a pair of cork balls be suspended. Towards the middle of A, bring the excited glass tube, and holding it a short time, at the distance of a few inches, each pair of balls will be observed to separate: withdraw the tube, and the balls of A will come together, and then repel each other again; but those of B will hardly be affected. By the approach of the excited glass tube, held under the balls of A, their repulsion will be increased: but if the tube be brought, in the same manner, towards the balls of B, their repulsion will be diminished.

In the fifth experiment, the common stock of electrical matter in the tin tube is supposed to be attenuated about the middle, and to be condensed at the ends, by the repelling power of the atmosphere of the excited glass tube, when held near it. And perhaps the tin tube may lose some of its natural quantity of the electrical fluid, before it receives any from the glass; as that fluid will more readily run off from the ends and edges of it, than enter at the middle: and accordingly, when the glass tube is withdrawn, and the fluid is again equally diffused through the apparatus, it is found to be electrified negatively: for excited glass brought under the balls will increase their repulsion.

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.

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 sometimes till they appear more than half-way towards the horizon. Rain, especially when the electrical fire; and hail, in summer, I bethe drops are large, generally brings down

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.

EXPERIMENT VIII.

Having made the Torricellian vacuum about five feet long, after the manner described in the Philosophical Transactions, vol. xlvii. P. 370, if the excited tube be brought within a small distance of it, a light will be seen through more than half its length; which soon vanishes, if the tube be not brought nearer; but will appear again, as that is moved farther offThis may be repeated several times, without exciting the tube afresh.

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; but as the tube is withdrawn, the fire is supposed

to return.

EXPERIMENT IX.

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.

lieve never fails.

last electrified, it was by the fall of thawing When the apparatus was snow, which happened so lately, as on the 12th of November; that being the twentysixth day, and sixty-first time it has been. electrified, since it was first set up; which 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.

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?

Experiments made in pursuance of those made by Mr. Canton, dated December 6, 1753; with explanations, by Benjamin Franklin.-Read at the Royal Society, Dec 18, 1755.

PHILADELPHIA, March 14, 1755. PRINCIPLES.

I. ELECTRIC atmospheres, that flow round non-electric bodies, being brought near each other, do not readily mix and unite into one atmosphere, but remain separate, and repel each other.

This is plainly seen in suspended cork-balls, and other bodies electrified.

II. An electric atmosphere not only repels another electric atmosphere, but will also repel the electric matter contained in the substance of a body approaching it; and without joining or mixing with it, force it to other parts of the body that contained it.

This is shown by some of the following experiments.

the atmosphere of the glass tube not having mixed with the atmosphere of the prime conductor, is withdrawn entire, having made no addition to, or diminution from it.

Bring the excited tube under the tuft of threads, and they will close a little. They close, because the atmosphere of the glass tube repels their atmosphere, and drives part of them back on the prime conductor. Withdraw it, and they will diverge as much. For the portion of atmosphere which they had lost returns to them again.

EXPERIMENT II.

Excite the glass tube, and approach the prime conductor with it, holding it across, near the end opposite to that on which the threads hang, at the distance of five or six inches. Keep it there a few seconds, and the threads of the tassels will diverge. Withdraw it, and they will close.

III. Bodies electrified negatively, or deprived of their natural quantity of electricity, They diverge, because they have received repel each other, (or at least appear to do so, electric atmospheres from the electric matter by a mutual receding) as well as those elec- before contained in the substance of the prime trified positively, or which have electric at-conductor; but which is now repelled and mospheres.

This is shown by applying the negatively charged wire of a phial to two cork-balls, suspended by silk threads, and many other experiments.

PREPARATION.

Fix a tassel of fifteen or twenty threads, three inches long, at one end of a tin prime conductor (mine is about five feet long, and four inches diameter) supported by silk lines. Let the threads be a little damp, but not wet.

EXPERIMENT I.

Pass an excited glass tube near the other end of the prime conductor, so as to give it some sparks, and the threads will diverge. Because each thread, as well as the prime conductor, has acquired an electric atmosphere, which repels and is repelled by the atmospheres of the other threads: if those several atmospheres would readily mix, the threads might unite and hang in the middle of one atmosphere, common to them all.

Rub the tube afresh, and approach the prime conductor therewith, crossways, near that end, but not nigh enough to give sparks; and the threads will diverge a little more. Because the atmosphere of the prime conductor is pressed by the atmosphere of the excited tube, and driven towards the end where the threads are, by which each thread acquires more atmosphere.

Withdraw the tube, and they will close as much.

They close as much, and no more; because

driven away, by the atmosphere of the glass tube, from the parts of the prime conductor opposite and nearest to that atmosphere, and forced out upon the surface of the prime conductor at its other end, and upon the threads hanging thereto. Were it any part of the atmosphere of the glass tube that flowed over and along the prime conductor to the threads, and gave them atmospheres (as is the case when a spark is given to the prime conductor from the glass tube) such part of the tube's atmosphere would have remained, and the threads drawing the tube, because the tube takes continue to diverge; but they close on withwith it all its own atmosphere, and the electric matter, which had been driven out of the substance of the prime conductor, and formed atmospheres round the threads, is thereby permitted to return to its place.

Take a spark from the prime conductor near the threads when they are diverged as before, and they will close.

For by so doing you take away their atmospheres, composed of the electric matter driven out of the substance of the prime conductor, as aforesaid, by the repellency of the atmosphere of the glass tube. By taking this spark you rob the prime conductor of part of its natural quantity of the electric matter, which part so taken is not supplied by the glass tube, for when that is aferwards withdrawn, it takes with it its whole atmosphere, and leaves the prime conductor electrised negatively, as appears by the next operation.

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.

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.

Keeping the tube in the same place with one hand, attempt to touch the threads with the finger of the other hand, and they will recede from the finger.

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.

He made first several experiments on fowls, and found, that two large thin glass 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 matter; for he did not see the flash, though his eye was on the spot of the prime conductor, from whence it struck the back of his hand; nor did he hear the crack, though the byBecause the finger being plunged into the standers said it was a loud one; nor did he atmosphere of the glass tube, as well as the particularly feel the stroke on his hand, though threads, part of its natural quantity is driven he afterwards found it had raised a swelling back through the hand and body, by that at- there, of the bigness of half a pistol-bullet. mosphere, and the finger becomes, as well as what numbed the remainder of the evening, the threads, negatively electrised, and so re- and his breast was sore for a week after, pels, 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 for it is not to be doubted, but several of these making these experiments with large jars; wards the prime conductor. Attempt to touch 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.

His arms and the back of the neck felt some

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. Differences in the Qualities of the Glass.--Account of Domien, an Electrician and Traveller.-Conjectures respecting the pores of Glass.-Origin of the author's idea of drawing down Lightning.—No satisfactory Hypothesis respecting the manner in which Clouds become electrified.-Six men knocked down at once by an electrical shock.-Reflections on the spirit of invention.

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.*

to support himself chiefly by electricity. A
strange project! But he was, as you observe,
a very singular character. I was sorry the
tubes did not get to the Havanna in time for
him. If they are still in being, please to
What
send for them, and accept of them.
became of him afterwards I have never
heard. He promised to write to me as often
as he could on his journey, and as soon as he
should get home after finishing his tour. It
is now seven years since he was here. If he
is still in New Spain, as you imagine from
that loose report, I suppose it must be that
they confine him there, and prevent his writ-
ing but I think it more likely that he may
be dead.

The questions you ask about the pores of In answer to your several inquiries. The glass, I cannot answer otherwise, than that I tubes and globes we use here, are chiefly know nothing of their nature; and supposimade here. The glass has a greenish cast, tions, however ingenious, are often mere misbut is clear and hard, and, I think, better for takes. My hypothesis, that they were smaller clectrical experiments than the white glass near the middle of the glass, too small to adof London, which is not so hard. There are mit the passage of electricity, which could certainly great differences in glass. A white globe I had made here some years since, pass through the surface till it came near the middle, was certainly wrong; for soon after I would never, by any means, be excited. Two had written that letter, I did, in order to conof my friends tried it, as well as myself, with- firm the hypothesis (which indeed I ought to out success. At length, putting it on an have done before I wrote it) make an experielectric stand, a chain from the prime con-ment. I ground away five sixths of the thickductor being in contact with it, I found it had ness of the glass, from the side of one of my the properties of a non-electric; for I could 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 292, for the paper bere referred to.

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 I found myself mistaken. The bottle charged as well after the grinding as before. I am now, 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 electricity in small quantities, and yet do not conduct it fast enough to produce the shock; but even 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 through twenty feet of wire, it passes through the wire, and not through the water, though 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 smart shock, one containing the same quantity of mercury will give one much stronger, the mercury being the better conductor; while one containing oil only, will scarce give any shock at all.

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