344 K. Honda and S. Sliimizu on Change of Length of 



decrease the contraction o£ length, and the amount of dimi- 

 nution increases with tension. In strong fields the con- 

 trary is the case. The tension increases the magnetic change 

 of length by an amount which increases with tension. 



Each curve in fig. 9, showing the relation between the 



Fig. 9. 



£000 4000 







\\~ 



20 





^-* 























"*V ( 



>o 









«irr^ 







260 — 























II 

 I 



change of length and the tension under constant field, has a 

 minimum point except in weak fields. This minimum occurs 

 at a greater load as the field is increased. These results 

 generally agree with those of Bidwell. 



7. Nickel- Steels. — The change of length under constant 

 tension of the annealed nickel-steel (45 per cent. Ni) is shown 

 in fig. 10. The change of length under ordinary conditions 



Fig. 10. 



SI 



I 































.~-6 













1--0 





1 













T~ 







du 



*te — 



/ 











T=463 













































T= I9S 



a 













ID 











I 





t2 



! 













i 



)0 



2( 



)0 





3( 



)0 



A- 



)0 



5 k 



6< 



10 H 



was already observed by Prof. Nagaoka and one of us. The 

 maximum elongation, which is characteristic for iron, is not 

 observed, but the wire simply elongates to an asymptotic 

 value as the field is increased . Compared with other ferro- 

 magnetics the effect of tension is comparatively large. It 

 diminishes elongation ; by a tension of 1*4 kilograms per 



