536 THE INTELLECTUAL RISE IN ELECTRICITY. 



So much for the jar. Now as to the circuit. By mid- 

 summer of 1747, Watson had gained a comprehensive idea 

 of the law of resistance, and states it thus : 



" This circuit, where the non-electrics (conducting sub- 

 stances), which happen to be between the outside of the 

 vial and its hook, conduct electricity equally well, is 

 always described in the shortest route possible ; but if they 

 conduct differently, this circuit is always formed through 

 the best conductor, how great soever its length is, rather 

 than through one which conducts not so well, though of 

 much less extent," in other words, he had established and 

 now announced that the resistance of a conductor to the 

 passage of electricity is proportional to its length, and, 

 other things being equal, depends upon the material of 

 which it is composed. 



