268 Messrs. H. Nagaoka and K. Honda on Magnetostriction. 

 Ovoid. Cylinder. 



H. 



I. 



*?xl0*. 



V 



2 



155 



0-1 



3 



340 



0-3 



4 



540 



0-4 



6 



800 



0-6 



12 



1100 



09 



17 



1200 



1-1 



29 



1270 



1-3 



49 



1340 



1-6 



113 



1470 



1-7 



151 



1510 



1-8 



203 



1560 



2-0 



251 



1630 



1-1 



H. 



I. 



*- y Xl0 7 . 



V 



5 



186 



01 



8 



308 



02 



14 



598 



0-3 



23 



804 



0-5 



34 



912 



0-6 



51 



998 



0-8 



85 



1109 



09 



102 



1143 



10 



155 



1220 



1-1 



207 



1280 



12 



These numbers plotted against H, I, and I s are shown in 

 figs. 1, 2, 3 (PI. 1.). Fig. 1 shows that iron increases in 

 volume very rapidly with the magnetizing-force ; but it soon 

 reaches the u Wendepunkt," whence to increase asymptotically 

 with further increase of the field-strength. Fig. 2 shows that 

 the increase of volume takes place very slowly with increase 

 of magnetization, but goes on rapidly as the magnetization 

 becomes stronger. It will be seen from fig. 3 that the increase 

 of volume is approximately proportional to the square of the 

 intensity of magnetization. 



Bidwell* found from measurement of the change of di- 

 mension of iron rings that there is diminution of volume in 

 weak field ; and experiments by Dr. Knott on the change of 

 internal volume seem to confirm the result. In the present 

 experiment with ovoid or with cylinder we found no such 

 diminution, but always increase of volume in iron. The 

 behaviour of iron, as regards the change of volume, is in 

 rough agreement with the result obtained by Dr. Knott with 

 tubes of wide bore. 



The following table gives the determination of the change 

 of volume in nickel. 



H. 



I. 



^XlO^. 



V 



55 



320 



-06 



74 



360 



-0-8 



101 



396 



-11 



127 



416 



-1-4 



152 



432 



-1-9 



188 



450 



-2-2 



288 



476 



-2-7 



391 



484 



-31 



640 



490 



-3-4 



Bidwell, Proc. Roy. Soc. vol. lvi. p. 94 (1894). 



