Notices respecting Neiv Books. 291 



Lecons sur la Theorie des Gaz. Par L. Boltzmann, Professeur d 

 V Univer site de Leipzig. Traduites par A. GrALLOTTi. Avec une 

 Introduction et des Notes de M. Brillouiin", Professeur au 

 College de France. Premiere Partie. Paris : Grauthier-Villars, 

 1902. Pp. xix+204. 



The kinetic theory of gases is a subject possessing a peculiar 

 fascination for the mathematical physicist : almost every dis- 

 tinguished member of that body has, at one time or another, 

 devoted a good deal of attention to it. The fascination seems to 

 be largely due to the difficulty of the subject, and to the extremely 

 wary manner in which an investigator must tread on this ground 

 if he is to avoid falling into countless pitfalls. Then, again, a 

 subject so full of delicate and debateable points is sure to be fruitful 

 of controversy ; and controversy is always stimulating, and ministers 

 to that lust of battle which, in some form or another, has always 

 dominated the human race. 



The results arrived at in the kinetic theory of gases are, however, 

 of much more than purely mathematical interest. As is the case 

 with all really important theories, the kinetic theory has powerfully 

 reacted on experimental science, and stimulated research. To the 

 experimenter, as well as the mathematician, it has yielded a rich 

 harvest of results. 



Those students who have neither the time nor the mathematical 

 equipment necessary for a full study of this important yet difficult 

 subject, will probably find the best account of it in a simple form 

 in Meyer's ' Kinetic Theory of Gases,' recently translated by 

 Mr. Baynes. To the advanced student, we can heartily commend 

 the work under review — the first part of a comprehensive treatise 

 on the subject by Professor L. Boltzmann. Pew authors could 

 speak with greater authority on this subject, and still fewer could 

 handle it in a manner at once so clear and cautious as that which 

 characterizes Prof. Boltzmann's treatment of it. 



The three chapters into which the present volume is divided 

 correspond to three hypotheses regarding the gaseous molecules: — ■ 

 (1) The molecules are elastic spheres ; there are no external forces, 

 and no sensible molar movements. (2) The molecules are centres 

 of force ; external forces and sensible molar displacements are 

 assumed to exist. (3) The molecules repel one another with a force 

 which varies inversely as the fifth power of the distance. 



One cannot help being struck by the evident care which the 

 author has taken to make the reasoning as clear as the nature of 

 the subject will permit, and to point out the exact limitations of 

 the results arrived at, and their connexion with the fundamental 

 assumptions on which they are based. 



M. Brillouin contributes an interesting introduction dealing 

 with the historical aspect of the subject, and some valuable 

 notes at the end which embody the results of the most recent 

 investigations. 



