164 



ELEMENTS OF STATIC ELECTRICITY. 



sighted position : and, in this way, the constancy of the 

 potential J^is tested. 



This constancy of potential is maintained by the 

 replenisher seen at JS, which is practically a small To- 

 pler machine ; and is shown separately in Fig. 54. A 

 and B are two insulated metal inductors, to which are 

 attached two receiver springs a and b. C and D are 

 two contact springs, in electric connection with each 

 other, but insulated from the other parts. 



P and Q are two metal 

 carriers, attached to an eb- 

 onite cross-piece, through 

 which passes the ebonite 

 axis T, which can be ro- 

 tated by the milled head 

 E: so that the carriers 

 P and $, revolving inside 

 the inductors A and B, 

 shall successively touch 

 the springs a, J>, b, 0. 



When the replenisher 

 is in its place, as shown 



in Fig. 52, the inductor A is put in electric connection 

 with the disc A ; which is supported in connection with 

 the inner coating of the Leyden jar : while the inductor 

 B, being in contact with the cover, is in electric con- 

 nection with the outer coating. And since the replen- 

 isher operates on the principle of the Topler machine, 

 already described, its rotation, either direct or reversed, 

 will raise or lower the potential of the jar : and so keep 

 the potential of the plate A, and of the idiostatic gauge, 

 connected with it, at the constant potential F", as 

 shown by the gauge. 



Fig. 54 The Replenisher. 



