5r»6 Prof. T. R. Lyle : Preliminary Account of 



galvanometer in one complete period is given by 



If (j){t) be the expression in the brackets we see that 



T 

 so that <^(^) is periodic, of period - , and contains only odd 



harmonics. 



Hence, if Ct^SpCP sin [poit^ Op) where ft)T = 27r, only 



those terms whose arguments are nwt, ^ticot, bncot, &c. need be 



considered in determining the value of (l>{t). Neglecting 



the other terms we find that the remainders of 



C<, -C,^T,C,^,I-, &c. -C,^<,„.,, 



are all equal to one another, and to the ?ith component of 

 Q, and as there are 2n of them 



<^(f) = 2n (?ith component) 



= 2nN say 



and the steady galvanometer deflexion jn will be the same as 

 that produced by a continuous current 



Sor '^nm. 



T or ,.^ 



X being the galvanometer factor, we find that 



rT 

 nNt=Xj^yny hence, &c. 



Similarly, when magnetic flux is under examination, if 

 ^,1 be the galvanometer deflexion when commutation occurs 

 '2n times per period, then n times the instantaneous value of 

 its nth component at alternate times of commutation is 



