DIELECTRIC MACHINE. 



211 



prime conductor or turned away from it. The rubbers and the 



lower comb are to be in 

 electrical communication 

 with the earth. The gene- 

 ral arrangement is clearly 

 set forth in the figure. 



348. Operation 

 of the Dielectric 

 Machine. The plate 

 B is turned directly by 

 the handle, and the plate 

 A indirectly by the aid 

 of the pulley. The plate 

 B is negatively electri- 

 fied by friction with the 

 rubber, and thus acts 

 by induction upon the 

 lower part of A, which 

 is thus polarized. The -f of this part of A is bound by the 

 attraction of the of B, while the of A is repelled, 

 escapes by the lower comb, and is replaced by -f from the 

 earth through the lower comb and its ground connection. 

 This part of A, thus positively charged, is soon removed 

 from the inducing body, and the + charge bound by B is 

 set free. It then comes to the upper comb, polarizes it and 

 the prime conductor by induction, exchanges some of its 

 own + for an equal amount of from the prime con- 

 ductor. This neutralizes that part of the upper plate, and 

 leaves the prime conductor positively charged. As each 

 successive part of A passes the lower comb it gives off 

 electricity and takes an equal amount of -f- ; as it passes 

 the upper comb it gives off -j- electricity and receives an 

 equal amount of . The charge of B is continually 



FIG. 147. 



