PHILOSOPHICAL TRANSACTIONS. 



I. Hie Influence of Stress and Strain on the Physical Properties of Matter. 

 Part I. Elasticity (continued). The Effect of Magnetisation on the Elasticity 

 and the Internal Fi-i<-ti,,,, of Metals. 



By HERBERT TOMLINSON, B.A. 

 Communicated by Pro/;.-..-..-/ W. GRYLLS ADAMS, M.A., F.R.S. 



Received May 18, Read May 27, 1886. 

 (Recast, with additions, December 16, 1887.) 



< h-iifin inut I'lir/ii'*' 1 i >f tin' Ii; xti, /< 



ACCORDING to Professor G. WIEDEMANN,* the main part of the internal friction which 

 occurs in a torsionally vibrating wire is due to the rotation of the molecules about 

 their axes, first to this side and then to that, as the wire vibrates to and fro. With 

 this view the author's own experimentst on the internal friction of metals had been 

 so far in accordance that he wished still further to test the matter by investigating 

 the effect of magnetisation on the internal friction. 



The author has already made some experiments on the effect of magnetisation on 

 the torsional elasticity of metals,! but the results of these experiments did not entirely 

 satisfy him, inasmuch as the means of eliminating the heating effect of the magnetising 

 solenoid were imperfect. It is true that the observed changes of temperature wrought 

 by the solenoid were comparatively small, but so also was the apparent alteration of 

 torsional elasticity due to magnetisation ; and it seemed, therefore, advisable to reopen 

 the inquiry, and to devise more perfect apparatus, whereby the heating effect above 

 mentioned might be entirely done away with. 



Description of Apparattis. 



The wire was clamped at its upper extremity, a, into a T-shaped block of brass 

 resting on the top of the air-chamber, A (see figure). The air-chamber consisted of two 



* ' WIEDBMANN'S Annalen,' 1879, vol. 6, p. 485. 

 t ' Phil. Trans.,' 1886 (vol. 177, Part II.). 



* ' Phil. Trans.,' 1883 (vol. 174, pp. 34, 35). 

 MDCCCLXXXVIII. A. B 31.1.88 



