10 ART. 9.— K. HONDA AND S. SHIMIZU : CHANGE IN LENGTH 



7. Nickfl Sted. Tlie magnetic change of Icngtli under 

 constant tension of tluî annoaUNl nickel steel (45% Ni) whose 

 thickness is 1.44 nini. is shown in Fig. S. The anomaly of the 

 magnetic elongation in nick(4 st('(4 had heen already observed hy 

 Professor Nao-aoka and one of us. The existence of a maximum 

 elongation, Avhich is the characfcrislic for iron, is not observed, but 

 the wire singularly elongates to an asymptotic value, as the held is 

 increased. Apart from otluT ferromagnetics, the effect of tension on 

 the magnetic elongation is considerably large ; the tension diminishes 

 the (4ongation, and by a tension of 1.4 kilograms j)er square milli- 

 meter, the elongation is already diminished to half its value 

 corresponding to no tension. 



To study s])ecially the effect of heavy loadings, a wire O.ôO min. 

 thick was made of the same alloy. After a- moderate annealing, it 

 was subjected to an experiment to see whether it would become 

 shorter than the initi;d length when magnetized under a heavy load- 

 ing. This actually occurred as shown in Fig. I). With a tension of 

 2(!.l) kilograms ])er square millimeter, the lerigth of the wire was 

 decideiUv shortened when maü'netized. Since the deuTee of annealin»;' 

 was different in the iWu-k iVoni the thin wire, the maii'netic chanofe 

 of length f(jr these two wires in the same held and tension did not 

 exactly coincide. 



The curves showing the relation between the change of length 



and the tension under a constant field is shown in Fig. 10. Here we 

 observe that the rate of the diminution of the maofnetic elon^'ation 

 becomes less, as the tension is increased. 



Some of the results of observations are «»'iveu in the followinfif 

 table : — 



