MEASUREMENT OF POTENTIAL DIFFERENCE 285 



the e.m.f. of the standard cell; Rh is the regulating rheostat; Si 

 is a reversing switch in the main circuit. 



The current entering at T l divides, the resistances being so 

 arranged that ten-elevenths of the total current flows to the left 



^ *tf^ J,N^I^*,'*^Jf^ I ^S2k* 



FIG. 164. Thermokraftfrei potentiometer. 



and one-eleventh to the right. The design is such that these 



relative values are maintained for all positions of the switches. 



Each coil in the decade I and in the group of compensating 



