Method of Comparing Inductance with Capacity. 39 



If the telephone is connected between two points P and Q, 

 then balance is attained if 



Bap R AQ (1 + Cnp) 



R' - (R" + Lip)(l + Crip)-r 2 Cip> ' ' {) 



This determines as the frequency at which a continuous 

 balance is possible : 



9 1 Rap .R" — Raq • R' fA \ 



P=LGr K^ ' • • ; (4) 



and we then obtain 



L __ 2 r^ Raq- R' — Rap . R " . ... (5) 



C Rap Rap 



If, as is usually done, a steady balance is first obtained, 

 then an inductive balance can occur only when p = 0, and 

 the method cannot be used with alternating current. When 

 p = 0, equations (4) and (5) give the usual conditions 



Rap R' ((»\ 



AQ J^ 



and L f . 



o= r (7 > 



§ o. In the Maxwell-Rimington arrangement the con- 

 denser is removed to the upper branch circuit, and it is no 



Fig. 2. 



longer impossible to obtain two points, one in each circuit, 

 such that the potential differences between them and A or 

 B are always of the same magnitude and in the same phase, 

 whatever the frequency may be. 



The current in the upper circuit is now 



°R'(l+ryO)-fSpC' * ' ' * K) 



where R' is the total resistance of that branch, and r is that 



