founded on Induction and Convection. 



67 



earth, and the other (the receiver-spring) with an insulated 

 piece of metal called the receiver, which is analogous to the 

 " prime conductor " of an ordinary electric machine. The point 

 of contact of the earth-spring with the carriers is exposed to the 

 influence of an electrified body (generally an insulated piece of 

 metal) called the inductor. When this is negatively electrified, 

 each carrier comes away from contact with the earth-spring,- 

 carrying positive electricity, which it gives up, through the re- 

 ceiver-spring, to the receiver. The receiver and inductor are 

 each hollowed out to a proper shape, and are properly placed to 

 surround, each as nearly as may be, the point of contact of the 

 corresponding spring. 



The inductor, for the good working of the machine, should be 

 kept electrified to a constant potential. This is effected by an 

 adjunct called the replenisher, which may be applied to the main 

 wheel, but which, for a large instrument, ought to be worked by 

 a much smaller carrier- wheel, attached either to the same or to 

 another turning-shaft. 



The replenisher consists chiefly of two properly shaped pieces 

 of metal called inductors, which are fixed in the neighbourhood 

 of a carrier- wheel, such as that described above, and four fixed 



Fig. 1. 



Secti on.. 



Elevation. 



springs touching the carriers at the ends of two diameters. Two 

 of these springs (called receiver-springs) are connected respect- 



F2 



