The Electrical Kite

To Peter Collinson, Esq. F.R.S., London.

致伦敦皇家学会会员彼得·柯林森先生。

Philadelphia, Oct. 19, 1752.

费城，1752年10月19日。

SIR,

先生：

As frequent mention is made in public papers from Europe of the success of the Philadelphia experiment for drawing the electric fire from clouds by means of pointed rods of iron erected on high buildings, &c. it may be agreeable to the curious to be informed that the same experiment has succeeded in Philadelphia, though made in a different and more easy manner, which is as follows:

欧洲的公共报刊上屡屡提到“费城实验”取得了成功，即借助竖立在高大建筑上的尖头铁杆，把电火从云中引下来，等等。好奇的人们或许乐于得知：同样的实验在费城也已成功，只是用了一种不同的、更简便的方法，如下：

Make a small cross of two light strips of cedar, the arms so long as to reach to the four corners of a large thin silk handkerchief when extended; tie the corners of the handkerchief to the extremities of the cross, so you have the body of a kite; which being properly accommodated with a tail, loop, and string, will rise in the air, like those made of paper; but this being of silk is fitter to bear the wet and wind of a thunder-gust without tearing. To the top of the upright stick of the cross is to be fixed a very sharp pointed wire, rising a foot or more above the wood. To the end of the twine, next the hand, is to be tied a silk ribbon, and where the silk and twine join, a key may be fastened. This kite is to be raised when a thunder-gust appears to be coming on, and the person who holds the string must stand within a door or window, or under some cover, so that the silk ribbon may not be wet; and care must be taken that the twine does not touch the frame of the door or window. As soon as any of the thunder clouds come over the kite, the pointed wire will draw the electric fire from them, and the kite, with all the twine, will be electrified, and the loose filaments of the twine will stand out every way, and be attracted by an approaching finger. And when the rain has wetted the kite and twine, so that it can conduct the electric fire freely, you will find it stream out plentifully from the key on the approach of your knuckle. At this key the phial may be charged; and from electric fire thus obtained, spirits may be kindled, and all the other electric experiments be performed, which are usually done by the help of a rubbed glass globe or tube, and thereby the sameness of the electric matter with that of lightning completely demonstrated.

用两根轻的雪松木条做一个十字架，木条的长短以能够到一块展开的大薄丝手帕的四个角为度；把手帕的四个角系在十字架的四个端头上，这样就有了风筝的骨架和面。再给它适当地配上尾巴、提线和放线，它就能像纸风筝一样飞上天；但这只风筝是丝做的，更经得住雷雨天的雨水和大风，不会撕破。在十字架竖木条的顶端，要固定一根非常尖的金属丝，高出木头一英尺或更多。在麻线靠近手的那一端，要系上一条丝带，在丝带与麻线相接的地方，可以拴一把钥匙。要在雷雨眼看就要来临的时候放起这只风筝，牵线的人必须站在门里或窗里，或者某个遮蔽物下面，好让丝带不被淋湿；还要当心不让麻线碰到门框或窗框。一旦有雷雨云飘到风筝上方，尖头金属丝就会把电火从云中引下来，风筝连同全部麻线都会带上电，麻线上松散的纤维会向四面八方竖起来，手指一靠近就被吸过去。等到雨水把风筝和麻线打湿，使它能畅通地传导电火，你会发现，当你的指节靠近钥匙时，电火从钥匙上大量地流泻出来。可以用这把钥匙给莱顿瓶充电；用这样得来的电火，可以点燃酒精，还可以做所有其他通常要靠摩擦玻璃球或玻璃管来做的电学实验；由此，电的物质与闪电的物质是同一种东西，就得到了完全的证明。

B. Franklin.

本·富兰克林