CH. xxix. BENJAMIN FRANKLIN. 253 



he learnt many of the newest improvements in printing. 

 After a time he went back to Philadelphia, and from that 

 time he began to succeed as a printer, and became a well- 

 known and respected man. 



It was in the year 1746 that he first began to pay atten- 

 tion to the experiments in electricity which were being made 

 in England and France. A great deal had been learnt 

 about this science since the time when Otto Guericke made 

 the first electrical machine in 1672, and a Frenchman 

 named Du Faye had shown that two different kinds of 

 electricity could be produced by rubbing different sub- 

 stances. You will remember that a pith-ball, when charged 

 with electricity from a stick of electrified sealing-wax, draws 

 back, and will not approach the sealing-wax again (see p. 

 122). But Du Faye discovered that if you rub the end of 

 a glass rod with silk, and bring it near to this ball, it will 

 draw the ball towards itself, showing that the electricity in 

 the glass rod has exactly the opposite effect to that in the 

 sealing-wax. In other words, while Guericke had shown 

 that substances charged with the same kind of electricity 

 repel each other, Du Faye showed that substances charged 

 with different kinds of electricity attract each other. Both 

 these men thought that electricity was a fluid which was 

 created by the rubbing, and which was not in bodies at 

 other times ; when Franklin, however, began to make his 

 experiments, he came to the conclusion that this was not as 

 they had supposed, but that all bodies have more or less 

 electricity in them, which the rubbing only brings out. 



The way in which he proved this is very interesting ; 

 but to understand it you must first know that any body 

 which is to be electrified requires to be so placed that the 

 electricity cannot pass away from it into the earth. The 

 best \vay to do this is to place it upon a stool with glass 



