250 



MEASUREMENT OF CURRENTS. 



circuit R alone, Ij its intensity in the resistance R + s of the circuit 

 and the shunt, I 2 in the resistance R and the galvanometer, and I 

 when a shunt of multiplying power m is added to the galvanometer. 

 The equations 



(34) E-I R = 



will enable us to calculate the different intensities I , I 15 and I 2 as a 

 function of the total intensity I, and therefore as a function of the 

 observed intensity z. 



In order that the intensity in the external circuit shall be the 

 same, whatever shunt is added to the galvanometer, a resistance p 

 must be inserted at the same time in the undivided circuit, such 

 that 



(35) 



With this object the arrangement represented in Fig. 167 is 



Fig. 167. 

 used, which explains itself: s, s', s" are the various shunts of 



cr 



, ^ , and p, p', p" resistances which 



resistances . 



m- i m - i m - i 



satisfy equations 



P=< 



