CH. xxix. EXPERIMENTS IN ELECTRICITY. 255 



This Franklin believed to be the case with all electricity, 

 namely, that every body contains its own amount of it, but 

 that when for any reason it is distributed unequally, those 

 which have no more than they can well carry, give some up 

 to those which have less, till they have each their right 

 quantity. And this explained at once why a man cannot 

 electrify himself, for so long as he has no one else from 

 whom he can procure electricity, he is only taking back with 

 one hand what he gives out with the other. Those who 

 had too much electricity were called by Franklin positively 

 electrified, and those who had too little, negatively electrified, 

 but the terms positive and negative are now used differently, 

 the one for vitreous the other for resinous electricity. 



Franklin draws down Lightning from the Sky. It 

 was in 1749, when he had already made most of his experi- 

 ments upon electricity, that Dr. Franklin began to consider 

 how many of the effects of thunder and lightning were the 

 same as those which he could produce with his electrical 

 machines. Lightning travels in a zigzag line, said he, and 

 so does an electric spark ; electricity sets things on fire, so 

 does lightning ; electricity melts metals, so does lightning. 

 Animals can be killed by both, and both cause blindness ; 

 electricity always finds its way along the best conductor, or 

 the substance which carries it most easily, so does lightning ; 

 pointed bodies attract the electric spark, and in the same 

 way lightning strikes spires, and trees, and mountain tops. 

 Is it not most likely that lightning is nothing more than 

 electricity passing from one cloud to another just as an 

 electric spark passes from one substance to another ? 



Franklin communicated these ideas to the Royal Society 

 in London, suggesting at the same time that, if he was right, 

 it would be possible to prevent a great deal of the harm 

 done by lightning by fixing upright rods of iron near high 



