On the Magnetization and Retentiveness 



of Nickel Wire under combined Torsional and 



Longitudinal Stresses. 



By 



H. Nagaoka, Rié^kushi, 



of the 

 Impc'iial University. 



Witli Plates XX -XXIV. 



Ill the experiment described in the jireceding paper, the maii-nctiz- 

 ing field around the nickel wire was kept constant, while the wire 

 itself was subjected to varying twists. The quite mtexpected re.sult.s 

 thus obtained suggested to ine the advisability of examining carefully 

 the maonetizatitin of nickel Avire at constant twists iimler tlie influ- 

 ence of gradually increasing and decreasing magnetizing fields. The 

 distinct lines of research presented themselves ; and the experiments 

 naturally fall to be discussed under two heads. 



(1.) There is the determination of the induced magnetism due 

 to various magnetizing forces in a twisted nickel wire subjected at 

 the same time to longitudinal stress. 



(2.) There is the investigation of the relation between the induced 

 and residual magnetisms under the conditions just specified. 



I. Relation between Magnetization and Magnetizing Force. 



The experiments to be described are concerned witli the peculi- 

 arities of magnetization of nickel wire suljject to comliined torsional 

 and longitudinal stres.ses. The wire under exainination was first 

 demagnetized by successive reversals of a current of gradually di- 

 minishing strength. A definite load was then appUed, and the wire 



