Читать книгу The Works of Benjamin Franklin, Volume 9 - Бенджамин Франклин - Страница 18

Passy, 2 October, 1781.

It is a long time, my dear friend, since I have had the pleasure of writing to you. I have postponed it too often from a desire of writing a good deal on various subjects, which I could not find sufficient time to think of properly. Your experiments on the conducting of heat was one subject; the finishing my remarks on the stroke of lightning in Italy was another. Then I was taken ill with a severe fit of the gout soon after you left us, which held me near three months, and put my business and correspondence so far behindhand that I was long in getting it up again. Add to this, that I find indolence increases with age, and that I have not near the activity I formerly had. But I cannot afford to lose your correspondence, in which I have always found so much pleasure and instruction. I now force myself to write, and I fancy this letter will be long.

I have now before me your several favors of December 5th, 1780, February 7th, April 7th, May 23d, and August 29th, 1781. I was glad to find by the first that you enjoyed a good state of health, and that you had leisure to pursue your philosophical inquiries. I wish you that continued success, which so much industry, sagacity, and exactness in making experiments have a right to expect. You will have much immediate pleasure by that success, and in time great reputation. But for the present the reputation will be given grudgingly, and in as small a quantity as possible, mixed, too, with some mortification. One would think that a man so laboring disinterestedly for the good of his fellow-creatures, could not possibly by such means make himself enemies; but there are minds who cannot bear that another should distinguish himself even by greater usefulness; and, though he demands no profit, nor any thing in return but the good-will of those he is serving, they will endeavor to deprive him of that, first, by disputing the truth of his experiments, then their utility; and, being defeated there, they finally dispute his right to them, and would give the credit of them to a man that lived three thousand years ago, or at three thousand leagues’ distance, rather than to a neighbor, or even a friend. Go on, however, and never be discouraged. Others have met with the same treatment before you, and will after you. And, whatever some may think and say, it is worth while to do men good, for the self-satisfaction one has in the reflection.

Your account of the experiments you made with the wires gave me a great deal of pleasure. I have shown it to several persons here, who think it exceedingly curious. If you should ever repeat those experiments, I wish your attention to one circumstance. I think it possible that, in dipping them into the wax, and taking them out suddenly, the metal which attracts heat most readily may chill and draw out with it a thicker coat of wax; and this thicker coat might, in the progress of the experiment, be longer melting. They should therefore be kept so long in the wax, as to be all and equally heated. Perhaps you may thus find the progress of heat in the silver quicker and greater. I think, also, that, if the hot oil in which you dipped the ends was not stagnant, but in motion, the experiment would be more complete, because the wire which quickest diminishes the heat of the oil next to it, finds soonest the difficulty of getting more heat from the oil farther distant, which depends on the nature of the oil as a conductor of heat, that which is already cooled interfering between the hotter oil and the wire. In reversing the experiment also, to try which of the metals cools fastest, I think the wires should be dipped in running cold water; for, when stagnant, the hot wires, by communicating heat to the water that is near them, will make it less capable of receiving more heat; and, as the metals which communicate their heat most freely and readily will soonest warm the water round them, the operation of such metals may therefore soonest stop; not because they naturally longer withhold their heat, but because the water near them is not in a state to receive it. I do not know that these hints are founded; I suggest them only as meriting a little consideration. Every one is surprised that the progress of the heat seems to have no connection with the gravity or the levity of the metals.

B. Franklin.