102 Messrs. K. Honda arid T. Terada on the 



\§Vb = fe kf, 9 W )h + w)b*(st)h + (^)h,/(bt)h 



= Wh/,Abt)e +2 w)h a A5t)h' • • • • ( 3 ) 



since we may put/=^. 

 If H is zero, we have 



"de _ m "df m—n 



§T " n(3m-n)' BT "~ 2«(3m— n) ; 



hence, neglecting the change of elastic constants by mag- 

 netization, we have, from (3), 



(bl\ _ « (bl\ rn-n /gl\ 



Hence, by (2) and (4), we get 



biV3hAa""vbt; h - 



But 



fewlsH/x^vdaXf,, 5 



+ 



hence finally we get 



As to the twist, J. J. Thomson obtained a relation which r 

 strictly speaking, holds in the case of a thin tube, i.e., 



^.-m(S).{'- h (I).}- • • <*> 



Here again in his original work, the factor J is dropped ; c 

 is not the twist t per unit-length, but it is connected with r 

 by the relation c — tt, where r is the radius of the thin 

 tube. As in the former case, we have 



xdnh 



