THE PHENOMENA OF ELECTROSTATICS. 



197 



by means of which it can be brought into contact with the point 

 / and then pushed into the interior of BB and brought into 

 contact with BB, repeatedly. Each time the carrier touches the 

 point p it receives a certain amount of charge from the battery 

 b, or in other words, a bundle of lines of force comes into exist- 

 ence between C and A A as shown in Fig. 1 1 8. As the car- 



Fig. 120. 



Fig. 121. 



rier is moved into the hollow vessel BB, the bundle of lines of 

 force trends as shown in Fig 119, and work has to be done to 

 move the carrier against the pull of these lines of force. As the 

 carrier is moved into BB the lines of force from C to AA 

 are cut in two, as it were, one after another, by the metal wall at 

 w, the portions of the lines of force which pass from C to AA, 

 as shown in Fig. 1 20, are then obliterated by bringing C into 

 contact with B, and the carrier C is left entirely neutral as 

 shown in Fig. 121. Each repetition of the above movements of 

 the carrier C " strings " an additional bundle of lines of force 

 from A to B and thus increases the intensity of the electrical 

 field between A and B. 



The production of a very large electromotive force between 

 A and B in Figs. 118 to 121 by the to and fro motion of the 



