368 Sir W. Snow Harris on the Laws and Operation [June 16, 



according to Cavendish it is as 1 : 1*15, which is not far different. It is 

 not unworthy of remark that the electrical relation of a square to a circular 

 plate of the same diameter, as determined by Cavendish nearly a century 

 since, is in near accordance with the formulse C= \/S above deduced. 



11. The author enumerates the following formulae as embracing the 

 general laws of quantity, surface, boundary extension, and intensity, prac- 

 tically useful in deducing the laws of statical electrical force. 



Symbols. 



Let C= electrical charge ; Q= quantity ; E= intensity, or electrometer 

 indication ; S= surface, B= boundary extension, or perimeter; A= direct 

 induction ; 1= reflected induction ; F= force ; D= distance. 



Fo7inulcB, 

 C a S, when S and B vary together. 

 C oc Q, E being constant, or equal 1 . 

 C Qc /y/S, B being constant, or equal 1 . 

 C a y^B, S being constant, or equal 1 . 

 C oc . B, when S and B vary together. 



E a — L- (Q being constant), for all plane rectangular surfaces. 

 o.B 



E a S being constant, or equal 1. 

 B 



E a 2, B being constant, or equal 1. 

 S 



E a J_, when S and B vary together. 



g2 







E oc Q,^ S being constant, or equal 1. 



C oc ^ 



In square plates, C a with side of square. 

 In circular plates, C oc with diameter. 

 In globes, C oc with diameter. 



A, or induction a S, all other things remaining the same. 



The same for 3, or reflected induction. 



In circular plates, globes, and closed and open surfaces, 



17 1 1 

 Ea_; or as-. 



F (=E) oc Q^ 



F or E a S being constant. 

 Generally we -have F a 



