144 JAMES CLERK MAXWELL 



theorem appears to give a unique solution, and the 

 Maxwell law of the distribution of tho energy to be 

 in fair accordance with tho results of observation.* 



If we can never go further and it must bo 

 admitted that tho difficulties in tho way of further 

 advanca are enormous it may, I think, bo claimed 

 for Maxwell that tho progress already made is greatly 

 due to him. Both these laws, for the case of clastic 

 spheres, are contained in his first paper of I860; 

 and while it is to the genius of Boltzmann that we owe 

 their earliest generalisation, and in particular tho 

 proof of tho uniqueness of the solution under proper 

 restrictions, Maxwell's last paper contributed in no 

 small degree to tho security of tho position. Not 

 merely the foundations, but much of tho super- 

 structure of molecular science is his work. 



Tho difficulties in tho way of advance are, as wo 

 have said, enormous. Boltzmann, in one of his papers, 

 has considered the properties of a complex molecule 

 of a gas, consisting maybe of a number of atoms 

 and possibly of ether atoms bound with them, and ho 

 concludes that such a molecule will behave in its 

 progressive motion, and in its collisions with other 

 molecules, nearly like a rigid body. Hut to quote 

 from Mr. Bryan: "The case of a polyatomic mole- 

 cule, whose atoms are capable of vibrating relative 

 to one another, affords an interesting Held for investi- 

 gation and speculation. Is the Boltzmann distribu- 

 tion still unique, or do other permanent distribu- 

 tions exist in which tho kinetic energy is unequally 

 divided ? " 



Sec papers l.y Mr. Caps-tick, Tint. Tran , vo!s. 185-180, 



