Effect of Rotatory Inertia on the Vibrations of Bars. 35 



simple to attack. Physiological chemistry, which ultimately 

 concerns itself mostly with complex solutions, will also be 

 •considerably simplified. It is interesting to find the attempt, 

 which I made to give a dynamical account of conductivity in 

 metals through a theory of their rigidity, supplemented by a 

 theory of electrolytic conduction in which temporary rigidity 

 •and its associated viscosity play a fundamental part. I have 

 sought to show also that nerve impulse is propagated by 

 rigidity of electric origin, and that the luminiferous aether, 

 if it contains electric doublets, must have a rigidity and a 

 density so related as to give the velocity of light through it. 

 If ever viscosity is discovered in the sether, it will be of 

 similar origin to that of the two types discussed here. The 

 ions of a solution give just such a distribution of polarity as 

 I have assumed to be at the basis of all rigidity. Hence the 

 deduction of the two new types of viscosity in electrolytic 

 solutions is a sort of confirmation of the electric origin of all 

 rigidity. A solution is in many respects a perfect model of 

 a polar medium interpenetrating another. 



Melbourne, April 1907. 



II. The Effect of Rotatory Inertia on the Vibrations of Bars. 

 'By J. H. C. Seaele, B.Sc* 



I. TT is well known that the rotatory inertia of a rod 

 JL modifies the notes emitted when transverse vibra- 

 tions are excited. The matter is referred to by Lord Rayleigh 

 in his ' Theory of Sound,' and the correction calculated for 

 a special case by the method of assuming normal functions 

 •of unchanged type. I have not been able, however, to find 

 any complete treatment of the subject in the usual biblio- 

 graphical authorities ; and it seemed worth while deducing 

 the exact and special formulae for the several cases, as well as 

 discussing the chief properties of the new normal functions. 



If it be suggested that the work will not repay the labour 

 involved as there are other corrections arising from the dis- 

 tortion and change of size of the cross-sections which are of 

 the same order, i.e. (width of bar /length of bar) 2 , the answer 

 must be that this is fully admitted. But all such corrections 

 are to a first order additive, and they can thus bs inde- 

 pendently found and allowed for. I shall hope to return to 

 the subject of what may be termed the elastic theory cor- 

 rections on another occasion. The present paper attempts to 

 deal fairly completely with the rotatory inertia terms and 



* Communicated by Prof. Karl Pearson, F.R.S. 

 D2 



