224 ELEMENTS OF STATIC ELECTRICITY. 



NOTE REFERRED TO ON PAGE 118. 



The brush from K makes its appearance first, and 

 increases in length till the brush from V appears; after 

 which it decreases in the same ratio as the brush from 

 V increases, till the discharge occurs, when both dis- 

 appear. This is sufficiently explained by increase and 

 decrease of difference of potential at different points. 

 As the potential of the revolving plate A increases, the 

 difference of potential between the inside coating of the 

 jar (7, and that part of A which receives the charge 

 from it through the comb K, decreases, as indicated by 

 the decrease in brush-length, till the potential of both 

 is the same, when the brush disappears. 



In like manner the potential of that part of the plate 

 A, passing the comb L, continues to increase till it 

 equals the potential of the inside coating of the jar D; 

 and this charged surface, passing on to the comb H, the 

 surplus of charge which D, from increase of potential 

 rejects, escapes through II to the comb V, and from V 

 to that part of the plate A between V and K, as indi- 

 cated by the increase of brush-length from V. 



This process is greatly intensified by the inductive 

 effect of the high potential of the lower part of inductor 

 T, and low potential of the upper part of inductor Jf, 

 by which electricity is repelled from the corresponding 

 lower part of the plate A to its corresponding upper 

 part. 



