206 H. NAGAOKA. 



strength of the magnetizing force is varied, we find gradual trans- 

 formations taking place. The magnetization curves in nickel for 

 small twists and weak longitudinal stresses are opposite in charac- 

 ter to those in iron for moderate twists. When the twist in 

 nickel exceeds l c .5 per cm., and the magnetizing force is sufficiently 

 strong, the magnetization curve loses its opposite character to that 

 of iron under moderate twists, and acquires a form similar to that for 

 iron subject to very large twist, as the comparison of Figs. 25 and 

 39 shews. 



Summary. — \ shall in conclusion summarise the results obtained 

 in the present experiment. 



In nickel under feeble longitudinal stress, there is reversal of 

 hysteresis when the range of twist is moderate. This phenomenon 

 takes place in lower magnetizing fields as the twist is increased. 

 When the amount of twist exceeds 3° per cm., nothing of this nature 

 is observed. The reversal of polarity, on the contrary, is a phenome- 

 non common to all twists, provided the longitudinal stress applied 

 be sufficiently great. 



In iron, so far as my experiments go, the magnetizing force does 

 not alter the character of hysteresis, but reversal of hysteresis takes 

 place when the twist exceeds 10° per cm., and the magnetization curve 

 bears a close resemblance to that of nickel in strong ma^netizim«' 

 fields for moderate twists. 



The effects of twist in iron and nickel, and especially in the lat- 

 ter, are so complicated that it is impossible to give anything like a 

 true explanation coordinating all these facts. The magnetic qualities 

 of these two metals with regard to stress are generally opposite. Not 

 only do twist and. longitudinal stress produce opposite effects in mag- 

 netization, but by twisting the wire in the magnetizing field we ob- 

 tain transient currents in opposite directions for these two metals and 



