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Mr. H. Tomlinson. The Influence of [Mar. 11, 



March 11, 1886. 



Professor STOKES, D.C.L., President, in the Chair. 



The Presents received were laid on the table, and thanks ordered 

 for them. 



The following Papers were read : — 



I. "The Influence of Stress and Strain on the Physical 

 Properties of Matter. Part I. Elasticity — continued. The 

 Internal Friction of Metals." By Herbert Tomlinson, B.A. 

 Communicated by Professor W. Grylls Adams, M.A., 

 F.R.S. Received February 18, 1886. 



(Abstract.) 



An abstract of a paper on this subject has been already published,* 

 but the paper itself was withdrawn for the purpose of revision. The 

 fresh experiments which have been for this purpose instituted during 

 the last year were made with improved apparatus, and the coefficient 

 of viscosity of air redetermined, with a view of enabling the author 

 to make more accurate correction for the effect of the resistance of the 

 air.f These more recent experiments on the loss of energy of a 

 torsionally vibrating wire, besides confirming the results of the older 

 ones, as far as the latter have been published, have furnished, more or 

 less in addition, the following facts relating to the internal molecular 

 friction of metals : — 



The proportionate diminution of amplitude is independent of the 

 amplitude, provided the deformations produced do not exceed a certain 

 limit. This limit varies with the nature of the metal, and is for 

 nickel very low. 



The logarithmic decrement of amplitude increases with the length 

 of the vibration-period, bat in a less proportion than the latter, and 

 in a diminishing ratio. The amount of increase of the logarithmic 

 decrement, attending on a given increase through a given range of 

 the vibration-period, varies with the nature of the metal, and with 

 those metals which possess comparatively small internal friction 

 becomes almost insensible. It follows as a consequence that the 



* "Proc. Roy. Soc," vol. 38, p. 42. 



t An abstracted account of this redetermination was read before the Royal 

 Society, January 14, 1886. 



