256 EIGHTEENTH CENTURY. PT. HI. 



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, and from 

 this come the terms positive and negative electricity, which 

 are now used. 



I should tell you here that it is now believed that 

 electricity is composed of two different kinds existing to- 

 gether in all substances. These two kinds are supposed to 

 remain at rest as long as they are equally balanced, but 

 when a body contains too much of one kind, it is always 

 trying either to give it up or to get some of the other kind 

 to balance it. This theory explains some facts which 

 Franklin's theory does not ; but it is not yet really known 

 what electricity is, only it is certain that Franklin was right 

 in saying that it is not created when we see its effects, but 

 only drawn out of bodies which contain it. 



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. 



