126 H. Nagaoka on Transient Electric Current produced 



changed by loading, the maximum current is increased. 

 At the same time, the point at which the current passes a 

 maximum is shifted towards stronger field. The loading does 

 not produce any remarkable change in the transient current. 

 Similar series of experiments were performed on an iron 

 wire 1*02 millim. thick and 30 centim. long (July 8, 1888). 

 The following Table gives the readings taken in different 

 magnetizing fields : — 



Iron wire {r = *51 millim., I = 30 centim., r = + 60°). 

 With no load on. Loaded 6*4 kgs. 





Reading of 



$. 



ballistic 





galvanometer. 



•34 



18 



1-1 



55 



1-8 



92 



36 



109 



4-7 



114 



6-8 



108 



100 



103 



20-1 



74 



31-8 



53 



410 



44 





Reading of 



£• 



ballistic 





galvanometer. 



•34 



45 



1-0 



21 



2-1 



36 



2-8 



40 



4-7 



47 



7-9 



50 



100 



49 



192 



39 



31-0 



30 



410 



24 





These and two others are shown graphically in fig. 2. A 

 glance at these curves will show that the transient current 

 at first increases rapidly as the field is increased, but soon 

 reaches a maximum and then begins to diminish gradually. 

 The application of longitudinal stress diminishes the current, 

 while at the same time the maximum point is transferred 

 towards higher magnetizing field. 



Comparing the results obtained for nickel and iron, we 

 notice a peculiar difference in the behaviour of these two 

 metals. The current which is produced by suddenly twisting 

 the wire in the magnetizing field is, in the first place, 

 opposite in direction. The direction* of the current in nickel 

 is such that, the twist being applied like a right-handed 

 screw, the current flows from south to north. In iron it is 

 from north to south. This singular fact was also noticed 

 later by Herr Zehnder. 



In the experiments hitherto described the magnetizing 

 force was gradually increased, and the transient current pro- 

 duced by suddenly twisting the wire at different magnetizing 



* See Note by Sir W. Thomson appended to this paper. 





