A HISTORY OF SCIENCE 



Franklin made his silk kite, with which he finally 

 demonstrated to his own and the world's satisfaction 

 that his theory was correct. 



Taking his kite out into an open common on the 

 approach of a thunder-storm, he flew it well up into 

 the threatening clouds, and then, touching the sus- 

 pended key with his knuckle, received the electric 

 spark ; and a little later he charegd a Ley den jar from 

 the electricity drawn from the clouds with his kite. 



In a brief but direct letter, he sent an account of his 

 kite and his experiment to England: 



" Make a small cross of two light strips of cedar," he 

 wrote, "the arms so long as to reach to the four cor- 

 ners 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 wind and wet of a 

 thunder-gust without tearing. To the top of the up- 

 right stick of the cross is to be fixed a very sharp-point- 

 ed wire, rising a foot or more above the wood. To the 

 end of the twine, next the hand, is to be tied a silk rib- 

 bon ; where the silk and twine join a key may be fasten- 

 ed. This kite is to be raised when a thunder-gust ap- 

 pears 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, 



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