12 W.N. Mill—Electro-Dynamometer for Large Currents. 
When the current passes, the suspended coil is powerfully 
deflected but its actual movement is limited by a vertical wire 
stop. There are two of these stops, one on each side of the 
pointer-rod of the suspended coil; They are about 15™ apart, 
so that the rod can move but 75™™ on either side the center. 
To the pointer-rod are attached on opposite sides, two silk 
threads which lead over pulleys on the side bars to small pans, 
one on each side of the instrument. (Fig. 1). The pulleys are 
62™ in diam. and have scores for the threads. They are light, 
nicely balanced and turn on hardened steel pivots. When de- 
flection has occurred, weights are added to the pan on the side 
opposite until the pointer-rod returns to the starting point. 
iP the weight added is too great, the pointer-rod is drawn 
against the other wire stop. Weights may then be removed 
or put into the opposite pan, until the right point is attained. 
