270 Prof. J. J. Thomson. The Resistance of [Jan. 17, 



is situated; F 2 , G 2 , H 2 their values in the conductor, and F 3 , G 3 , H 3 

 their values on the side of the slab remote from the primary system. 

 Let be the electrostatic potential, and let us suppose that all the 

 quantities vary as e 1 ^, then 



p -fi"_i_ " d $ 

 r = JJ H --- :-, 



ip ax 



TT _TI'_J_ 



1 11 H -- , 



ip dz 



F' dG' cZH' 



where v is a constant which depends on the theory of electricity 

 we adopt. If we assume Maxwell's theory, v = 1, and as we shall see 

 reason later on for believing that v has always this value, we shall 

 henceforth in this investigation assume this value for it. F', G', H' 

 represent transverse disturbances propagated in a dielectric with the 

 velocity of propagation of electrodynamic action. 



Let 



where the terms of the type B 1 e t ( a - r+6 2 /+cz+ ^) represent the disturbance 

 proceeding from the primary, and those of the type B 1 'e l 

 the disturbance reflected from the plate. 



Let F 3 



ip 



1 , 



Go = , 9 > 



ipdy 



--, 

 ip dz 



F., = Boe l ( a: +^+ C3+ ^) + ^ , 

 ip dx 



-^ , 



ip dy 



H = .> 



ip dz 



