EFFECT OF STRESS ON MAGNETIZATION. ^5 



Among till tlie specimens tested, nickel allbrds the best 

 evidence in favonr of the theories above tested. The 

 discrepancies due to the diH'erence of the orders of a})plying 

 the stress and the field, are generally small, when com- 

 pared with those in the case of other specimens. The agreement 

 is especially good in the case of tension eifect, if the term 'y'TTT 

 be suj^pressed ; the difference between the values -7^.7 and 

 —Typ is of such orders of magnitude that they may be explained 

 by the errors introduced in estimating these values from the corre- 

 sponding diagrams. P'or the rest of the specimens, the agreement 

 is tolerably good in many cases, except a few cases in which it 



completely fails. Generally speaking, the tension effect shows a 



.fig 

 better agreement between theory and experiment, if -^rr be 



fi/ 



0/ 



compared with -r^ ; while —^ deduced from the {I,H)r 

 curve is often of a different order of magnitude, as in the case of 

 2S.74Yo Ni. As for the comparison between —"m "yT/ ^^^^ 

 YFpT » the agreement is less remarkable, but the discrepancies 

 may in many cases be due to the errors introduced in estimating 

 the curvature of the curves for obtaining -^tiw • ~^jw de- 

 duced from (/, H)j. curve is often of a different order of magnitude, 

 as in the case of Swedish iron. For torsion effect, things 

 are much more complicated, except in the case of nickel and 

 nickel steels of 28.74 and 70.32 per cent of nickel, in which the 

 agreement is fairly good. For the last two specimens, -^ -r-j- 

 generally agrees with -- — q^ or -^^ -^-^ , while in the 

 case of 50.729^ Ni., the former is of a different sign from the 

 latter for small twist. In all cases, the discrepancies become less 

 in high fields. 



As to the term -^- .^rr obtained by Grans and Sano, it 

 may be noticed that its introduction makes the agreement between 



