268 Mr KELLAND, ON THE MOTION OF 



and by what has been shewn in (4), 



4P p _ /- ^ef . 



the quantity — r<r.^-— ,- sm'-r^ is positive: 

 let it be equal to 2««-, and we shall have 



On examining the investigation for light, we perceive that the 

 solution of the last two equations was suggested by that of the 

 approximate ones 



Cpy U- id'y 



df k* Xdx"' 



and applying the same suggestion to this case, we should have to 

 solve the equation 



d' a 2ir d'a _ 



W ^ If d^ " ' 



which would arise from supposing the extent of influence of the par- 

 ticles small, or the length of a wave large. 



This equation is nearly identical, in form, with that, which Fourier 

 has so amply discussed in his treatise on Heat. 



35. It may not be uninteresting to compare the results in the 

 case of inelastic fluids with ours. I shall adopt the usual notation, and 

 suppose the motion to take place in the following manner. A series 

 of waves is transmitted along the axis of x, whilst the motion of an 



