JOURNAL OF THE COLLEGE OF SCIENCE, IMPERIAL UNIVERSITY, 

 TOKYO, JAPAN. 



VOL. XVI, ARTICLE 9. 



Change in Length of Ferromagnetic Wires under 

 Constant Tension by Magnetization. 



By 



K. Honda, Rigakushi, 



and 

 S. Shimizu, Rlgakushi. 



With Plates I— 11. 



1. In his earliest experiment on the change in length by 

 magnetization of iron and steel rods, Joule^^ noticed that the effect of 

 tension is to diminish the magnetic elongation, and that if the 

 tension exceeds a certain limit, the magnetization causes contraction 

 instead of elongation. Repeating the same experiment, S. BidwelP^ 

 made special investigations on this point. His results can be stated 

 in the following words : Tension diminishes the magnetic elongation 

 of iron, and causes the magnetic contraction to take place with a 

 smaller magnetizing force ; it increases the contraction in strong fields. 

 These chano;es become o-reater as the tension is increased. For 

 nickel, the magnetic contraction is diminished by tension in weak 

 fields ; but it is increased in strono; fields. These chano;es also 



1) Joule, Phil. Mag. 30. 76, 225, 1847. 



2) Bidwell, Pro. Eoy. Soc. 40, 109, 257, 1886; Pro. Eoy. Soc. 47, 469, 1890 ; Ewing's 

 Magnetic Induction p. 240. 



