362 



Mr. H. Tomlinson. The Influence of [June 16, 



deeply furrowed in a plane parallel to the axis of rotation, so as to be 

 shaped like a dumb-bell, and although this result can only be taken 

 to represent the truth very roughly, yet it cannot be entirely explained 

 by the imperfection of the analytical method employed. It appears 

 then as if the smaller body were on the point of separating into two 

 masses, in the same sort of way that the Jacobian ellipsoid may be 

 traced through the dumb-bell shape until it becomes two masses. 



M. Poincare has commented in his paper on the possibility of the 

 application of his results, so as to throw light on the genesis of a 

 satellite according to the nebular hypothesis, and this investigation 

 was undertaken with such an expectation. He remarks, however, 

 that the conditions for the separation from a mass, which is strongly 

 concentrated at its centre, are necessarily very different from those 

 which he has treated mathematically. 



However, both his investigation and the considerations adduced 

 here seem to show that, when a portion of the central body becomes 

 detached through increasing angular velocity, the portion should bear 

 a far larger ratio to the remainder than is observed in our satellites, 

 as compared with their planets ; and it is hardly probable that the 

 heterogeneity of the central body can make so great a difference in 

 the results as would be necessary, if we are to make an application of 

 these ideas. 



It seems then at present necessary to suppose that after the birth 

 of a satellite, if it takes place at all in this way, a series of changes 

 occur which are still quite unknown. 



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

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

 Velocity of Sound in Metals, and a Comparison of their 

 Moduli of Torsional and Longitudinal Elasticities as 

 determined by Statical and Kinetical Methods." By 

 Herbert Tomlinson, B.A. Communicated by Professor 

 W. Grylls Adams, M.A., F.R.S. Received April 29, 1887. 



(Abstract.) 



The principal object of the investigation was to ascertain whether 

 the values of the moduli of torsional and longitudinal elasticities, as 

 determined by statical methods, would be the same as when deter- 

 mined by kinetical methods, provided the deformations produced were 

 very small. 



The method of determining the modulus of longitudinal elasticity 

 statically has been already described.* This method was applied with 



* ' Phil. Trans.,' 1883, Part I. 



