Infiiienci' of Stress on Mdancl'ic CJiamje of Iles'istance. (JD3 



Substitutino for .r ami // their values, we get in the expres- 

 sion for 7 terms of the types 



QOs[imt±{)i-l)ht), (.'0^(iiwt±(n — \\)ht), .... 



the h\st term is cos nayt if n is odd, cos (wa)/ + 8/) if n is even. 

 Thus at rioht-anoles to the direction of the magnetic force 

 tlie effect is much more comi)lieated than along that direc- 

 tion. At riorht-anoles to the maonetic force the line whose 

 frequency is nw is split u}) into lines whose frequencies are 

 nw^^nh^ 71(0 + (n — 2) S, 7iq) + {ii-'4:)S . . : the last term being 

 7i(t}±'28, or wa) + S, as n is even or odd; all these lines are 

 })olarized in the plane parallel to the magnetic force : 

 besides these we have lines whose frequencies are nw +{n — 1)3, 

 7/Q)+(w — 3)8, the last term being 7ico or 7ia) + S as 7i is odd or 

 even ; all these lines are polarized in the plane at right-angles 

 to the magnetic force. Thus while the original line is, 

 looking in the direction of the magnetic force, only split 

 into two whose frequencies are ?ift) + 8 ; in the direction at 

 right-angles to the force it is split into 2n or 2n+l lines 

 according as 7i is even or odd, wdiile the maximum change of 

 frequency is n times that for the radiation along the lines of 

 force. 



LXXXV. yitf hifluence of Stress and of Temperature on the 

 Mafjnetic Chamje of Resistance in Iron^ JSickel^ and Nickel- 

 Stetl. By W.'E. Williams, B.Sc."^ 



[Plate XXVII.] 



rj'^HE influence of stress on the magnetic change of resist- 

 X ance in iron and nickel has been investigated by 

 Tomlinsonf; and in a paper previously communicated to the 

 l^hilosophical Magazine J the present writer described some 

 experiments on the same subject. The results obtained 

 seemed to indicate that a further investigation of this effect 

 both in nickel and in iron would be desirable ; and the expe- 

 riments described below were undertaken with that object. 



The present paper also contains an account of experiments 

 on the effects of variations of temperature on the magnetic 

 change of resistance. This effect has been investigated for 

 the case of nickel by Dr. Knott §. As, how^ever, his expe- 

 riments were confined to fields below 60 c.C4.s. units^ while 



* Communicated by Prof. E. Taylor Jones. 



t Phil. Trans. Roy. Soc. 1883, Pt. 1. 



t Phil. Ma?. Oct. 1902. 



§ Xrans. Roy. Soc. Edinburgh, xl. pt. iii. ^'o. 23. 



