20 ELEMENTARY LESSONS ON [CHAP. i. 



tricity. It appears then that positive electricity attracts 

 negative and repels positive, and that this influence can 

 be exerted at a distance from a body. If we had begun 

 with a charge of negative electricity upon a stick of seal- 

 ing-wax, the presence of the negative electricity near the 

 conductor would have induced positive electricity on the 

 near end, and negative on the far end. This action, 

 discovered in 1753 by John Canton, is spoken of as 

 electric induction, or influence. It will take place 

 across a considerable distance. Even if a large sheet 

 of glass be placed between, the same effect will be 

 produced. When the electrified body is removed both 

 the electricities disappear and leave no trace behind, and 

 the glass ball is found to be just as much electrified as 

 before ; it has parted with none of its own charge. It 

 will be remembered that on one theory a body charged 

 with + electricity is regarded as having more electricity 

 than the things round it, while one charged with 

 electricity is regarded as having less. According to 

 this view it would appear that when a body (such as the 

 + electrified glass ball) having more electricity than 

 things around it is placed near an insulated conductor, 

 the uniform distribution of electricity in that conductor 

 is disturbed, the electricity flowing away from that end 

 which is near the + body, leaving less than usual at 

 that end, and producing more than usual at the other 

 end. This view of things will account for the disappear- 

 ance of all signs of electrification when the electrified 

 body is removed, for then the conductor returns to its 

 former condition ; and being neither more nor less elec- 

 ^ trifled than all the objects around on the surface of the 

 earth, will show neither positive nor negative electricity. 

 19. If the conductor be made in two parts, so that 

 while under the inductive influence of the electrified 

 body they can be separated, then on the removal of the 

 electrified body the two electricities can no longer return 

 to neutralise one another, but remain each on their own 



