264 H. NAGAOKA AND K. HONDA : 



as we are aware, no attemi^t lias yet been made to place all of 

 these difierent phenomena on a, common footing. Some time ago^\ 

 we hinted at the probable connections which exist between 

 the twist caused by passing an electric current through a longi- 

 tudinally magnetized wire and the change of volume and of 

 length in ferromagnetic metals produced by magnetization. The 

 said relation can also be extended to the explanation of other 

 phenomena ; namely, the transient current produced by twisting a 

 magnetized wire and the longitudinal magnetization caused by 

 twisting a circularly magnetized wire. It is our object in the 

 present paper to show that these different phenomena can be 

 linked together in a common bond. 



§ 1. Twist produced by the interaction of circular 

 and longitudinal magnetizations. 



The subject was first studied by G. Wiedemann'-'^ who esta- 

 blished remarkable reciprocal relations with the longitudinal 

 magnetization produced by twisting a circularly magnetized wire. 

 Dr. Knott"^ found that the direction of twist in iron is opposite 

 to that in nickel ; BidwelP' afterwards discovered that the twist 

 in iron is reversed in high fields and takes place in the same 

 direction as in nickel. Unfortunately some of the experiments 

 were undertaken with wires which were longer than that of the 

 coil, so that the magnetization was far from being uniform. It 

 will suffice for qualitative tests, but we can not hojDe for any 



l)Nagaoka and Honda, this Journ. 13, p. 57, 1900; Phil. mag. 49, p. 341, 1900. 

 2)G. Wiedemann, Pugg. Ann. 103, p. 571, 1858; 106, P- 1<J1, 1859; Elcktridtäi, 3. 

 :]) Knott, Trans. Koy. Sue. Edinb., 32 Ü), p. 193, 1882/8;]; 35(2), p. 377, 1889; 36 (2), 

 p. 485, 1891. 



