Moving Force. 135 
city is taken in a sense quite different from 
that in which it appears to have been under- 
stood by every other author I have had an 
opportunity of consulting, he proceeds :— 
_ Parmi toutes les fonctions mathématiquement 
possibles, examinons quelle est celle de la na- 
” 
ture. 
various effects of force he concludes, “ Voila 
And after reasoning at some length on 
donc deux lois du mouvement, savoir, la lois 
d’inertie et celle de la force proportionnelle a 
la vitesse, qui sont données par l’observation. 
Elles sont les plus naturelles et les plus simples 
que l’on puisse imaginer, et. sans doute, elles 
dérivent de la nature meme de la matiére ; 
mais: cette nature étant inconnue, ces lois ne 
sont: pour nous, que des faits observés, les 
seuls, au ai Bs la mécanique emprounte 
de l’expérience.’’* 
It appears then to be the opinion of this dis- 
tinguished philosopher, that, although it may 
be mathematically possible for the force of a 
body in motion to be-proportional to the square 
of its velocity, yet such a principle is incon- 
sistent with the phenomena of nature; but 
that the law of imertia, and the law of force 
proportional to the velocity, are the most natu- 
tural and the most simple principles imagin- 
able, that they are derived from the very 
* Systéme du Monde, p. 144. 
