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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 rarefied, give electrical fire to, and air, suddenly condensed, receive electrical fire from, clouds and vapors 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 upper part of the atmosphere, where the resistance is least?

• TO JAMES BOWDOIN.

Concerning the Light emitted by Salt Water. The Abbe Nollefs Letters on Electricity.

Philadelphia, 13 December, 175a

Dear Sir,

I received your favor of the 12th ultimo, with the law of your province for regulating the Indian trade, for which I thank you, and for the remarks that accompany it, which clearly evince the usefulness of the law, and I hope will be sufficient to induce our Assembly to follow your example,

I have yet received no particulars of the unhappy gentleman's death at Petersburg, (whose fate I lament.)

Vol. v. 43 cc

One of the papers says, that all the letters from thence confirm the account, and mentions his name, (Professor Richmann,) but nothing farther. No doubt we shall have a minute account of the accident with all its circumstances, in some of the magazines or the Transactions of the Royal Society.*

The observation you made of the sea water emitting more and less light, in different tracts passed through by your boat, is new; and your manner of accounting for it ingenious. It is indeed very possible, that an extremely small animalcule, too small to be visible even by the best glasses, may yet give a visible light. I remember to have taken notice, in a drop of kennel water, magnified by the solar microscope to the bigness of a cart-wheel, there were numbers of visible animalcules of various sizes swimming about; but I was sure there were likewise some which I could not see, even with that magnifier; for the wake they made in swimming to and fro was very visible, though the body that made it was not so. Now, if I could see the wake of an invisible animalcule, I imagine I might much more easily see its light, if it were of the luminous kind. For how small is the extent of a ship's wake, compared with that of the light of her lantern.

My barometer will not show the luminous appearance by agitating the mercury in the dark, but I think yours does. Please to try whether it will, when agitated, attract a fine thread hung near the top of the tube.

As to the answer to Nollet, if I were going on with

• Professor Richmann was killed at Petersburg, on the 26th of July, 1753, while repeating Franklin's experiment for bringing electricity from the clouds. He received a shock, which caused instantaneous death. A full account of the circumstances attending his death is contained in the Philosophical Transaction!, Vol. XLVIII. p. 765; and Vol. XLIX. p. 61. — Editor.

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it, I should be extremely glad of your peeping into it (as you say) now and then, that I might correct it by your advice. The materials in short hints have been long collected and methodized; they only want to be clothed with expression. But, soon after my return from New England, I received the enclosed from Monsieur Dalibard, wherein he tells me, that he is preparing an answer, not only to the Abbe, but to some others that have wrote against my doctrine, which will be published the beginning of this winter. This, with a good deal of business, and a little natural indolence, has made me neglect finishing my answer, till I shall see what is done by him. Perhaps it may then appear unnecessary for me to do any thing farther in it. And will not one's vanity be more gratified in seeing one's adversary confuted by a disciple, than even by one's self? I am, however, a little concerned for Dalibard, when I find by his letter, that he has been so far imposed on by the Abbe's confident assertion, that a charged bottle placed on an electric per se loses its electricity, as to attempt to account for it, when the thing is absolutely not fact. I have in answer wrote him my sentiments on that and some other particulars of the Abbe's book, which I hope will get to hand before his answer is published.

I am, with the greatest esteem and regard,
Dear Sir, your most obliged humble servant,

B. Franklin.

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TO PETER COLLINSON.

Additional Proofs of the Positive and Negative State of Electricity in the Clouds. New Method of ascertaining it.

Philadelphia, 18 April, 1754.

Sir,

Since September last, having been abroad on two long journeys, and otherwise much engaged} I have made but few observations on the positive and negative state of electricity in the clouds. But Mr. Kinnersley kept his rod and bells in good order, and has made many.

Once this winter the bells rang a long time during a fall of snow, though no thunder was heard, or lightning seen. Sometimes the flashes and cracks of the electric matter between bell and bell were so large and loud as to be heard all over the house; but, by all his observations, the clouds were constantly'in a negative State, till about six weeks ago, when he found them once to change in a few minutes from the negative to the positive. About a fortnight after that, he made another observation of the same kind; and last Monday afternoon, the wind blowing hard at southeast, and veering round to northeast, with many thick, driving clbuds, there were five or six successive changes from negative to positive, and from positive to negative, the bells stopping a minute or two between every change. Besides the methods mentioned in my paper of September last, of discovering the electrical state of the clouds, the following may be used. When your bells are ringing, pass a rubbed tube by the edge of the bell, connected with your pointed rod; if the cloud is then in a negative state, the ringing will stop; if in a positive state, it will continue, and perhaps be quicker. Or, suspend a very small cork ball by a fine silk thread, so that it may hang close to the edge of the rod-bell; then, whenever the bell is electrified, whether positively or negatively, the little ball will be repelled, and continue at some distance from the bell. Have ready a round-headed glass stopper of a decanter, rub it on your side till it is electrified, then present it to the cork ball. If the electricity in the ball is positive, it will be repelled from the glass stopper, as well as from the bell; if negative, it will fly to the stopper.

B. Franklin.

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