COMPARISON OF SELF-INDUCTION AND RESISTANCE. 513 



Further, since no electricity passes in the branch CD, we have 



also 



'=/?'. 



Eliminating a, /?, /5', and V, we get 



. 



dt a a b 



The second member is zero if the bridge is in equilibrium for 



a permanent state. The first member will also be zero, and there 

 will be equilibrium for the variable state, provided 



The adjustment can only be made by trials. It requires three 

 variable resistances, two of which, a and , are standardised in the 

 two branches which are free. 



The formulae of electrical oscillations, reduced, as in 1056, to 



give also a ^relation between the duration, the capacity, and the 

 coefficient of self-induction, which might be utilised in practice. 



1100. COMPARISON OF A COEFFICIENT OF SELF-INDUCTION 

 WITH A RESISTANCE. Let us suppose the coil placed in the 



VOL. II. L L 



