104: Messrs. K. Honda and T. Terada on the 



Rensing experimentally tested relation (9) in the case of 

 iron and nickel, and showed a fair agreement between the 

 theory and the experiment. 



R. Gans criticised Heydweiller's equations and proposed 

 his own, i. e., 



dH 4*r3T ' 4ttE "V/* 



" 4tt 3T ^ 4ttE Vo'BH A 



If the medium surrounding the magnet be air, we may put 

 /jl = 1 ; hence 



a«_ai , 1(1-2*) 27tbp nm 



BH ~ BT E + E BH * * ' • K - V) 



Thus, Gans's equation differs from that of Heydweiller by 



the term w ^= 9 which generally is not very small, but in 



weak fields it sometimes overweighs the first term. As in 

 the case of Heydweiller, differentiating the above relation 

 with respect to T, Gans obtained an expression for the change 

 of elasticity which differs from that of Heydweiller by the 



term — ^ ^ r ,^ rr . Here again, it was assumed that cr and 



E are independent of T, a supposition not admissible in a 

 magnetized wire. 



By a similar consideration as Heydweiller, A. Kolacek 

 obtained equation (8), and also a relation between magnetism 

 and twist, i. e., 



(11) 



where s is the cross-section of the wire. Since 



L=|RVn, 



the above equation becomes 



~dr_ 2 BI 

 BH~7iR 2 Bt' ' * ' * 



which coincides with equation (9). 



M. Cantone obtained two relations by equating the change 

 of magnetic energy due to a tension or a twist to the change 

 of elastic energy caused by magnetization, i. e., 



(12) 



= -rrn 1 Hdl and t»i = s ^-y- I Hdl, 



