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satisfaction, and met with many articles, especially from the foreign publications, which were new to me. It is indeed a most noble collection of every thing relating to that science.

In my last I ventured to mention a little slip concerning the satellites of Saturn. It would be miraculous, if, in so large a work collected from such a number of books and on such a variety of matters, there should not be many such. I noted the few that occurred to me in the chapters taken from those authors I was most acquainted with, and beg leave to enclose a list of the principal of them. There are not above two or three of them that are of any consequence; however, such as it is, the list is at Dr. Priestley's service, if you think it worth sending to him. It may help to remove a few trifling inaccuracies from that valuable work.

I have enclosed the newspaper you mention, that gave an account of the thunder-storm we had here a few years ago. As you are collecting facts on this subject, I looked over my old Almanacs where I had made some memoranda relating to your admirable lightning bells. I think it would not be worth while to transcribe them all, nor can I collect any thing from them but what is commonly known. In general, it seems that the bells hardly ever ring in the summer without a shower; they sometimes ring when there is no thunder or lightning, but do not always ring when there is. When there is a thunder shower, they generally ring most briskly while the cloud is yet at some distance, and cease as soon as it rains hard. In winter they frequently ring briskly in snow-storms, and twice they have done so after the weather was cleared up, and while the new-fallen snow was driving about with the wind, as you have done me the honor already to publish.


In looking for the newspaper before mentioned, I met with another, which gives an account of damage done by lightning in some places in Connecticut in 1771. As perhaps you have not seen it, I enclose it with the other; also, a letter sent me with another account. In my Almanacs I found also a few minutes relating to some uncommon appearances of the Aurora Borealis. I do not know that they can be of any use, but if they will afford you the least amusement I will readily transcribe them.

In addition to my newspaper account, I would mention that besides the strokes of lightning on the College and the elm tree, July 2d, 1768, there was another discharge that afternoon on a cornfield, at a little distance from the College towards the southeast. It spoiled the corn,* which was of some height, in a circle of about twenty feet diameter. That near the centre was burnt down to the roots, as I was informed by the owner. I did not hear of it till some days after, and when I saw the place it had been replanted with cabbages. The corn near the circumference of the circle was only scorched, and I saw the leaves withered and drooping. The place struck was about midway between a tree on one side, and the well-pole and chimney of the house on the other, and, as I judge, about eighty feet distant from each; and there was nothing near so high on the other sides for a considerable distance. Hence, their protection did not extend eighty feet. If a person had been standing in that corn, I suppose there is no doubt that he would have been killed. And therefore a person in the midst of an open plain is by no means secure from the stroke

* Indian corn, or maize, which is most commonly planted in this neighbourhood.-Note by Dr. Franklin. VOL. VI.




of lightning. The best security seems to be to have something high, as a tree for example, near him, but not too near; perhaps from thirty or forty to ten or fifteen feet, or rather to be near two such trees.

I am, &c.



On the Causes of Colds.

10 March, 1773. I shall not attempt to explain why damp clothes occasion colds, rather than wet ones, because I doubt the fact; I imagine that neither the one nor the other contribute to this effect, and that the causes of colds are totally independent of wet and even of cold. I

propose writing a short paper on this subject, the first moment of leisure I have at my disposal. In the mean time I can only say, that, having some suspicions that the common notion, which attributes to cold the property of stopping the pores and obstructing perspiration, was ill founded, I engaged a young physician, who is making some experiments with Sanctorius's balance, to estimate the different proportions of his perspiration, when remaining one hour quite naked, and another warmly clothed. He pursued the experiment in this alternate manner for eight hours successively, and found his perspiration almost double during those hours in which he was naked.


* Translated from M. Dubourg's edition of Franklin's Works, Vol. II. p. 311.- EDITOR.


Mr. Wilson's Opposition to Pointed Conductors. — M.

Le Roy Chosen a Member of the American Philosophical Society.

London, 30 March, 1773. DEAR SIR, You punish my delay of writing to you very properly, by.not writing to me. It is long since I have had the pleasure of hearing from you. But it is my fault, and I must for my own sake write to you oftener, though I have little to say, or you will quite forget me.

I thank you for your advice to send an English copy of my writings to the Academy, and shall do it as soon as the new edition now in hand here is finished.

I am glad you see some weight in the experiments I sent you concerning pointed rods. Mr. Wilson is grown angry, that his advice was not followed in making them 'blunt for the public magazines of gunpowder, and has published a pamphlet reflecting on the Royal Society, the committee, and myself, with some asperity, and endeavouring to alarm the city with the supposed danger of pointed rods drawing the lightning into them, and blowing them up. I find it is expected from me that I make some answer to it, and I shall do so, though I have an extreme aversion to public altercation on philosophic points, and have never yet disputed with any one, who thought fit to attack my opinions. I am obliged to you for the experiment of the point and ring.

There is no being sure of any thing before it happens; but, considering the weight of your reputation, I think there is little reason to doubt the success of your friends' endeavours to procure from our Society here the honor of adding you to their number at the next election. In the mean time will


sake confer the same kind of honor on our young Society at Philadelphia. When I found that our first volume of American Transactions was favorably received in Europe, and had procured us some reputation, I took the liberty of nominating you for a member, and you were accordingly chosen at a full meeting in Philadelphia on the 15th of January last. I sent a copy of that volume to the Academy of Sciences at Paris, when it first came out, but I do not remember to have heard that they ever received it. I think it was Mr. Magalhaens,* who undertook to convey it. If it miscarried, I will send another, and by the first opportunity one for yourself.

Two ships are now fitting out here by the Admiralty, at the request of the Royal Society, to make a voyage to the north pole, or to go as near to it as the ice will permit. If they return safe we shall probably obtain some new geographical knowledge, and some addition to natural history. With the greatest esteem and respect, I am, &c.


* John Hyacinth de Magalhaens, a Portuguese by birth, who resided a large part of his life in England. His name frequently occurs in Franklin's letters. He is said to have been “an able linguist, and well versed in chemistry and natural philosophy," and to have published respectable treatises on mineralogy, and some other branches of science. He was a member of the Royal Society. This is the same person (whose name is sometimes printed Magellan) that gave to the American Philosophical Society a donation of two hundred guineas, which was to be invested in a secure fund, and the interest disposed of annually in premiums to the author of the best discovery, or most useful invention, relating to navigation, astronomy, or natural philosophy. -EDITOR.

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