526 



Mr. A. 0. Allen on 



respectively. This is easily seen, because T is equivalent 

 to T. — -~ — and T . — p— in parallel ; these are proportional 



to E. and S, and non-inductive, so that it makes no difference 

 whether they are joined at both ends or only at the battery 



P+Q 



end ; and in the latter case T . — ^r— '■ is thrown into B, and 



P + Q ^ 



T . — p-^ into S. All the results of § 2 then apply. (I am 



indebted to Prof. Stroud for this characteristically neat 

 explanation.) 



§ 6. Anderson's method is the correlative of the preceding, 

 but interposes T in the conjugate position, i. e. between the 

 condenser and galvanometer on one side, and the arms Q and 

 S on the other. The balance is continuous ; the method of 



04- S 

 last paragraph may be used, i. e. we may split T into T . — ^— - 



O 4- S ^ 



and T. — ~ — , and then throw these into Q and S respectively, 



and apply all the results of § 2. 



§ 7. Maxwell's method for comparing two inductances 

 gives a continuous balance, as would be expected, from the 

 symmetry of the arrangement. Just as in § 2, we may 



show that short-circuiting isolates the action of the respective 



halves; L discharges through P and R, 1/ through Q and S, 



L L/ 



the two time-constants p — p- and ~ ~ being equal. 



§ 8. Niven, avoiding the double adjustment, sacrifices the 

 continuous balance again. The equations at short-circuiting 

 the battery include the following : — 



R#-Sy-(?D + G+R+S)s-(R+S)w=0; 



