of the Coefficients of Induction. 457 



coil in secohms, and A is the current in amperes flowing 

 through it. The experiments are in fair accordance with the 

 relation 



L 2 =-2A + -0425. 



Since A is proportional to «£), and L 3 is proportional to 33/«£), 

 the above experiments tend to show that the part of the curve 

 of magnetization between the points corresponding with the 

 currents "047 and "107 ampere is a parabola of the form 



5. It was, however, desirable to see whether this relation 

 would still hold good for smaller magnetizing forces. With 

 this view the experiments were repeated some months after- 

 wards in a somewhat different way. The coefficient was 

 determined by comparing it with the capacity of a standard 

 condenser. Two arms,p, q, of a Wheatstone bridge (see fig. 2) 

 consisted of doubly wound resistance-coils of 10,000 ohms each. 

 The resistance g of the galvanometer used was also about 



Fig. 2. 



To the coil q was shunted a condenser of 

 ^ microfarad capacity. The opposite branch r of the bridge 

 contained the electromagnet whose self-induction was re- 

 quired. The resistance of the arm s was 5 ohms, and that of 

 r was adjusted till there was balance. The battery used was 



