A KINETIC THEORY OF MATTER. 219 



durete des corps depends on petits tourbillons)- 

 These words, embedded in a hopeless mass of 

 unintelligible statements of the physical, meta- 

 physical, and theological philosophies of the day, 

 and unsupported by any explanation, elucidation, 

 or illustration throughout the rest of the three 

 volumes, and only marred by any other single 

 sentence or word to be found in the great book, 

 still do express a distinct conception, which forms 

 a most remarkable step towards the kinetic theory 

 of matter. A little later we have Daniel Bern- 

 oulli's promulgation of what we now accept as 

 a surest article of scientific faith the kinetic 

 theory of gases. He, so far as I know, thought 

 only of the Boyle's and Harriot's law of the 

 " spring of air," as Boyle called it, without reference 

 to change of temperature or the augmentation of 



1 " Preuve de la supposition que j'ay faite : Que la matiere subtile 

 ou etheree est necessairement composee de PETITS TOURBILLONS ; 

 et qu'ils sont les causes naturelles de tous changements qui arrivent 

 a la matiere ; ce que je confirme par 1'explication des effets les plus 

 generaux de la Physique, tels que sont la durete des corps, leur 

 fluidite, leur pesanteur, leur legerete, la lumiere refraction et 

 reflexion de ses rayons." MALEBRANCHE. Recherche de la Vtrite', 

 1712. 



