138 Dr. J. Moser on the Division of Induction in the 



Let us call b the distance of the sole from the positive sur- 

 face, and d the distance of the cover from the negative layer. 



If c is the thickness of the ebonite plate, a layer of air 

 thinner in the ratio of the inductive capacity of the ebonite 

 (2*2) would correspond to it, L e. of the thickness 



/ c 



so that in our scheme the four metal plates would stand at the 

 distances 



b, c f , d. 



The rubbed side may contain the quantity of electricity 



-E; 



and from the sole the part 



+ «E 



of the induced quantity may have passed on the unrubbed 

 surface : 



| b \ c> | d |. 

 Sole. +*E. -E. Cover. 



Then, according to the equations (1), (3), and (4), the quan- 

 tity — E induces a total amount of + E, viz.: — 



In the sole. In the cover. 



+ d E. 



b + c' + d 



+ b + c' E 

 b + c' + d 



In the same manner the quantity of the lower side + «E in- 

 duces a total of — aE, viz.: — 



In the sole 

 — etc' —ad 



In the cover. 

 -*b 



b + c' + d 



E. 



In the cover. 

 + b + c' — ah -™ 

 b + c' + d 



b + c' + d 

 So that all together is induced : 



In the sole. 

 + d — ac' — ud 

 b + c' + d 



The numerator of the electric quantity in the cover 



+ b + c' — ab 



is always positive. That is, there is always induced in the 

 metallic covering on the side of the rubbed surface positive elec- 

 tricity; and we get, on removing the plate, a positive spark. 



On the other hand, we recognize that the numerator of the 

 electric quantity in the sole 



+ d— etc' — ad = d(l — a) — etc', 



