264 Dr. J. W. Nicholson on the 



A similar potential H = B'K (t/i/o) leaving the second wire 

 produces secondary potentials 



H = ^- B ' S8 -Jo(fe-) •••• (48) 

 naa , , /, 2 °i°2 



1 + ^°^3 

 „_ B'0 O % J (k'r) r , 9 



M - 1S^-7^8A' • • • ' v"> 



in the first and second respectively, and as 

 B * EJ„'(fa) b } 



phfju OL J v 



so 



F= *' Ej '(^) m m m (50) 



so that the secondaries may be exactly analogous to the first 

 group. 



The value of H in the first wire is therefore, to this order, 



H= {A - ™1% 1 + >«<& *■ ) J„ (kr) (51) 



with a corresponding total current 



->=£'•'<*»). dfe- • • • (52) 



As previously indicated, Aa and Afr are to be supposed very 

 small, so that ha J ' (ha) is of order (lia) 2 . 



Neglecting this order of magnitude, a justification for the 

 process appearing later, 



(53) 



S 2 =-^Jo'(W)J' 

 and therefore 



B -?% B '=if^ ; - • • • < 54 > 



and in the first wire, on reduction, 



