OX TRANSIENT ELECTRIC CURRENTS. ; > S 1 



for r= 0.50 r-70°, 



„ r=0.65 r-45°, 



„ r=0.84 r-3G°, 



„ r-1.00 r=30°. 



The curves also resemble those obtained in similar experiments 

 with iron. 



When the nickel wire is loaded and then subjected to varying 

 twists, the curves of transient current present a peculiar aspect, 

 especially when the field is weak. To test this for thick 

 wires, experiments were performed with wires 1.68 mm. and 

 2.00 mm. thick respectively. The curves (see Fig. XVI.) thus 

 obtained show the same characteristics as before noticed. After pass- 

 ing the maximum point, the decrease of the transient current takes 

 place very rapidly. The current, a little while after, becomes 

 insisrniticantly small, so that for large twists, it is insensible to the 

 galvanometer. Thus the peculiarity seems not to be due to the thick- 

 ness of the wire. 



In niv former paper. I had occasion to remark that the transient 

 current curve resembles the curve of the Wiedemann effect. In the 

 latter, the twist due to superposed circular and longitudinal mag- 

 netization of the wire increases at first with increase of the magnetiz- 

 ing force, but ultimately reaches a maximum. According to the 

 researches of Professor Knott, the twist in nickel takes place in the 

 opposite sense to that in iron, and the maximum twist in the former 

 occurs in much higher magnetizing fields than in the latter. These 

 facts are in every way similar to those observed in the transient cur- 

 rent. Following the close analogy between the Wiedemann effect and 

 the transient current, experiments were made in order to find if the 

 similarity can be pushed even to very strong magnetizing fields. Ac- 

 cording to Mr. Bidwell, the Wiedemann effect in iron is reversed when 



