The Works of Benjamin Franklin, Volume 5. Бенджамин Франклин

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СКАЧАТЬ by informing you that as the ordinary method of swimming is reduced to the act of rowing with the arms and legs, and is consequently a laborious and fatiguing operation when the space of water to be crossed is considerable, there is a method in which a swimmer may pass to a great distance with much facility, by means of a sail. This discovery I fortunately made by accident, and in the following manner:

      When I was a boy I amused myself one day with flying a paper kite; and approaching the bank of a pond, which was near a mile broad, I tied the string to a stake and the kite ascended to a very considerable height above the pond while I was swimming. In a little time, being desirous of amusing myself with my kite, and enjoying at the same time the pleasure of swimming, I returned, and loosing from the stake the string with the little stick which was fastened to it, went again into the water, where I found that, lying on my back and holding the stick in my hands, I was drawn along the surface of the water in a very agreeable manner. Having then engaged another boy to carry my clothes round the pond, to a place which I pointed out to him on the other side, I began to cross the pond with my kite, which carried me quite over without the least fatigue, and with the greatest pleasure imaginable. I was only obliged occasionally to halt a little in my course and resist its progress when it appeared that, by following too quick, I lowered the kite too much; by doing which occasionally I made it rise again. I have never since that time practised this singular mode of swimming, though I think it not impossible to cross in this manner from Dover to Calais. The packet-boat, however, is still preferable.

       B. Franklin.

      

      CCCXXXV. TO JOHN WINTHROP

      London, 2 July, 1768.

      Dear Sir:—

      You must needs think the time long that your instruments have been in hand. Sundry circumstances have occasioned the delay. Mr. Short, who undertook to make the telescope, was long in a bad state of health, and much in the country for the benefit of the air. He however at length finished the material parts that required his own hand, and waited only for something about the mounting that was to have been done by another workman, when he was removed by death. I have put in my claim to the instrument, and shall obtain it from the executors as soon as his affairs can be settled. It is now become much more valuable than it would have been if he had lived, as he excelled all others in that branch. The price agreed for was one hundred pounds.

      The equal altitudes and transit instrument was undertaken by Mr. Bird, who doing all his work with his own hands for the sake of greater truth and exactness, one must have patience that expects any thing from him. He is so singularly eminent in his way, that the commissioners of longitude have lately given him five hundred pounds merely to discover and make public his method of dividing instruments. I send it you herewith. But what has made him longer in producing your instrument is the great and hasty demand on him from France and Russia, and our Society here, for instruments to go to different parts of the world for observing the next transit of Venus; some to be used in Siberia, some for the observers that go to the South Seas, some for those that go to Hudson’s Bay. These are now all completed and mostly gone, it being necessary, on account of the distance, that they should go this year to be ready on the spot in time. And now he tells me he can finish yours, and that I shall have it next week. Possibly he may keep his word. But we are not to wonder if he does not.

      Mr. Martin, when I called to see his panopticon, had not one ready; but was to let me know when he should have one to show me. I have not since heard from him, but will call again.

      Mr. Maskelyne wishes much that some of the governments in North America would send an astronomer to Lake Superior to observe this transit. I know no one of them likely to have a spirit for such an undertaking, unless it be the Massachusetts, or that have a person and instruments suitable. He presents you one of his pamphlets, which I now send you, together with two letters from him to me relating to that observation. If your health and strength were sufficient for such an expedition, I should be glad to hear you had taken it. Possibly you may have an élève that is capable. The fitting you out to observe the former transit, was a public act for the benefit of science, that did your province great honor.

      We expect soon a new volume of the Transactions, in which your piece will be printed. I have not yet got the separate ones which I ordered.

      It is perhaps not so extraordinary that unlearned men, such as commonly compose our church vestries, should not yet be acquainted with, and sensible of the benefits of metal conductors in averting the stroke of lightning, and preserving our houses from its violent effects, or that they should be still prejudiced against the use of such conductors, when we see how long even philosophers, men of extensive science and great ingenuity, can hold out against the evidence of new knowledge that does not square with their preconceptions ^{Ref. 003}; and how long men can retain a practice that is conformable to their prejudices, and expect a benefit from such practice though constant experience shows its inutility. A late piece of the Abbé Nollet, printed last year in the Memoirs of the French Academy of Sciences, affords strong instances of this; for, though the very relations he gives of the effects of lightning in several churches and other buildings show clearly that it was conducted from one part to another by wires, gildings, and other pieces of metal that were within or connected with the building, yet in the same paper he objects to the providing metalline conductors without the building, as useless or dangerous. ^{Ref. 004} He cautions people not to ring the church bells during a thunder-storm, lest the lightning, in its way to the earth, should be conducted down to them by the bell-ropes, ^{Ref. 005} which are but bad conductors, and yet is against fixing metal rods on the outside of the steeple, which are known to be much better conductors, and which it would certainly choose to pass in, rather than in dry hemp. And, though for a thousand years past bells have been solemnly consecrated by the Romish Church, ^{Ref. 006} in expectation that the sound of such blessed bells would drive away the storms, and secure our buildings from the stroke of lightning; and during so long a period, it has not been found by experience that places within the reach of such blessed sound are safer than others where it is never heard; but that, on the contrary, the lightning seems to strike steeples of choice, and that at the very time the bells are ringing ^{Ref. 007}; yet still they continue to bless the new bells, and jangle the old ones whenever it thunders. One would think it was now time to try some other trick; and ours is recommended (whatever this able philosopher may have been told to the contrary) by more than twelve years’ experience, wherein, among the great number of houses furnished with iron rods in North America, not one so guarded has been materially hurt with lightning, and several have evidently been preserved by their means; while a number of houses, churches, barns, ships, &c., in different places, unprovided with rods, have been struck and greatly damaged, demolished, or burnt. Probably the vestries of our English churches are not generally well acquainted with these facts; otherwise, since as good Protestants they have no faith in the blessing of bells, they would be less excusable in not providing this other security for their respective churches, and for the good people that may happen to be assembled in them during a tempest, especially as those buildings from their greater height, are more exposed to the stroke of lightning than our common dwellings.

      I have nothing new in the philosophical way to communicate to you, except what follows. When I was last year in Germany, I met with a singular kind of glass, being a tube about eight inches long, half an inch in diameter, with a hollow ball of near an inch diameter at one end, and one of an inch and a half at the other, hermetically sealed, and half filled with water. If one end is held in the hand, and the other a little elevated above the level, a constant succession of large bubbles proceeds from the end in the hand to the other end, making an appearance that puzzled me much, till I found that the space not filled with water was also free from air, and either filled with a subtile, invisible vapor continually rising from the water, and extremely rarefiable by the least heat at one end, and condensable again by the least coolness at the other; or it is the very fluid of СКАЧАТЬ