128 H. Nagaoka on Transient Electric Current produced 



is in opposite sense to that of nickel. Moreover the 

 maximum twist in iron occurs in lower magnetizing field than 

 that in nickel. These facts closely resemble the transient 

 current produced by twisting nickel and iron wires. In fact 

 Professor J. J. Thomson* has shown that the existence of 

 the Wiedemann effect necessarily leads to the production of 

 electromotive force by twisting a longitudinally magnetized 

 wire. According to Shelford Bidwellt the Wiedemann effect 

 in iron comes out in the same sense as in nickel when the 

 magnetizing force is sufficiently increased. In order to see 

 if there is any such similarity in these two phenomena, the 

 transient current produced in high magnetizing field was 

 examined. 



Using the dynamo current, a magnetizing force of 300 or 

 400 units was easily obtained, and observations made with 

 nickel wire are as follows (July 11, 1888) : — 



Nickel wire (r = '5 millim., I = 30 centim.). 



$. 



Eeading of 



ballistic 

 galvanometer. 



Twist. 





333 



55 



o 



±60 



Under no load. 



409 



43 



±60 



„ 



333 



66 



±60 



Loaded 3 kgs. 



321 



81 



±60 



„ 6 „ 



333 



91 



±90 



.. 6 „ 



The transient current in nickel wire diminishes with the 

 increase of the magnetizing force, as will be seen from the 

 readiugs given above. Even in a field of 300 units, the load- 

 ing produces increase of the current- strength. 



With an iron wire 1*46 millim. thick and 30 centim. long, 

 and twisted through 60°, the following readings were taken: — 



©■ 



Reading. 



Twist. 



202 



3-5 



o 



±60 



338 



Inappreciable. 



±60 



404 



j> 



±60 



550 



» 



±60 



* See ' Application of Dynamics to Physics and Chemistry/ d. 70. 

 t Phil. Mag. September 1886. 



