Researches on Magnetostriction 



By 

 H. Nagaoka, Rigakuhakushl, 



Professor of Applied Mathematics, 

 and 



K. Honda, Rigakushi, 

 Post-graduate in Physics. 



With Plates XVIII Sç XIX. 



The object of the present investigation is two-fold ; firstly, to 

 determine the effect of hydrostatic pressure on the magnetization of 

 iron and nickel and to find whether there exist reciprocal relations 

 between the effects of compression and the volume change of ferro- 

 magnetics by magnetization ; secondly, to examine Kirchhoff's 

 theory of magnetostriction from the measurement of strains produced 

 by magnetization, and from the effects of stress on the magnetization 

 of iron and nickel. 



Both experiments and theory show that physical changes are 

 mostly reciprocal. In magnetism, the fact is markedly brought out 

 by the mutual relation of twist and magnetization 2) as well as by the 

 change of length by magnetization and the effect of longitudinal 

 pull applied to the magnetized wire. The theoretical exposition of 



1). Kirclihoff, Sitzber. d. Acad. d. Wits, zu Berlin, p. 137, 1884; IVied. Ann. 24, 52. 1885; 

 Gesammelte Abhandlungen, Nachtrag, p. 91, Leipzig (1891) ; See also Pearson's History of 

 elasticity, II, §§ 1313-1321. 



2). See Wiedemann's Electricität, III (1895). 



