230 POPULAR LECTURES AND ADDRESSES. 



cule has the requisite properties, we might rest 

 happy for a while in the contemplation of the 

 kinetic theory of gases, and its explanation of 

 the gaseous properties, which is not only stupend- 

 ously important as a step towards a more thorough- 

 going theory of matter, but is undoubtedly 

 the expression of a perfectly intelligible and 

 definite set of facts in nature. But, alas, for our 

 mechanical model, consisting of the cloud of 

 little elastic solids flying about amongst one 

 another. Though each particle have absolutely 

 perfect elasticity, the end must be pretty much 

 the same as if it were but imperfectly elastic. 

 The average effect of repeated and repeated 

 mutual collisions must be to gradually convert 

 all the translational energy into energy of shriller 

 and shriller vibrations of the molecule. It seems 

 certain that each collision must leave something 

 more of energy in vibrations of very finely 

 divided nodal parts than there was of energy 

 of such vibrations before the impact. The more 

 minute this nodal subdivision, the less must be 

 the tendency to give up part of the vibrational 



