116 ELEMENTS OF STATIC ELECTRICITY. 



Fig. 37, page 111, represents the machine with the 

 sliding electrodes P and R separated. Suppose the 

 switch AS' to be closed and the machine put in operation. 

 It will be seen that as the plate A revolves, the raised 

 centers of the six carriers are brought into contact with 

 the wire brushes attached to the holders E and F; each 

 opposite pair touching opposite brushes, successively, 

 at the same instant. The friction generates electricity, 

 which diffuses itself over the carriers on A, and the in- 

 ductors on J5, with which they are, at the instant of 

 contact, in electric connection. The potential of car- 

 rier and inductor, during contact, will be the same ; at 

 the next instant the carrier passes on, and is insulated 

 from the inductor, and carrier and inductor now act in- 

 ductively on each other, and multiply the initial charge 

 given by the friction of contact. As it accumulates, it 

 spreads over the paper inductors ; these act on the 

 opposite surfaces of the glass, till both surfaces of both 

 plates become charged ; the initial charge being still 

 continued by the constant friction of the carriers and 

 brushes. 



But, since both sides of the machine are of similar 

 construction, and since the mode of action on both 

 sides is apparently the same, the question arises, how 

 any difference of potential, or electric charge can be 

 accounted for. 



And first, it will be noticed, that the position of the 

 plates being vertical, their lower halves are nearer to 

 the earth, by their semi diameter, than the upper halves, 

 and consequently, more under the influence of its in- 

 ductive action, by the square of that distance. The 

 lower halves are also in close proximity to the Leyden 

 jars, the driving wheel, and the belt, and subject to their 



