40 Dr. J. P. Dalton on a New Continuous-Balance 



part of it which is across the condenser terminals ; while in 

 the lower circuit the current is 



E ° (9) 



n"+Li> 



In Rimington's method the indicator is placed between Q 

 and a point X between A and P, so that the voltages which 

 must be equal in order to obtain a balance are 



¥L'(l + ripQ)-rHp(? 



across AX -Eo- p//-, , JLn\ ^Ln ? . . . . (1U) 



and across AQ 



n AQ .+~Lip nn 



and there is, in general, but one (real) frequency for which 

 these are equal. For that we find 



2 _ Raq . R ; — Rax ■ R ' / 1 o\ 



p ~ LCr(RxB-r) ^ } 



And then L = _^_ { ^ aq _ (Raq . U '-K ax . r» )} . ( i 3) 



Here again, i£ a steady balance is first arranged an in- 

 ductive balance cannot be obtained with alternating current. 

 With/>=0 (12) and (13) become the usual 



Rax R' 



Raq R 



s S7"' ' 



C " Rr- { } 



..... (14) 

 and L ^ 2 Raq 



kxb 



In Maxwell's original method the indicator was placed 

 between Q and P ; the points X and P are then coincident, 

 and r = R X B- Continuous balance is then possible at all 

 frequencies, and the second relation becomes 



ti=RxbRaq. ..... (16) 



§ 4. In the Rimington method the phase difference between 

 the voltages across the arms AX and AQ and the applied 



e.m.f. are of the form tan" 1 , P , ,, where a, b, and c are 



b + cp 2 



constants, so that, in general, these phases can be the same 



for one particular frequency only. But let us look for a 



moment at the conditions obtaining along the branch PB. 



