Corpuscules of Le Sage. 323 



une latitude, que les rendoit egalement compatibles avec plusieurs 

 autres hypotheses ; qu'aussi, Ton ne manqua pasde lui opposer : 

 au lieu que, les consequences du choc des Atoms • auroient ete 

 absolument univoques en faveur du seul principe veritable (des 

 Accelerations egales en Tempuscules egaux)." 



If Le Sage had but excepted Kepler's third law, it must be 

 admitted that his case, as stated above, would have been 

 thoroughly established by the arguments of his " memoire ; " 

 for the Epicurean assumption of parallelism adopted to suit the 

 false idea of the earth being flat, prevented the discovery of the 

 law of the inverse square of the distance, which the mathema- 

 ticians of that day were quite competent to make, if the hypothesis 

 of atoms moving in all directions through space, and rarely coming 

 into collision with one another, had been set before them, with 

 the problem of determining the force with which the impacts 

 would press together two spherical bodies, such as the earth and 

 moon were held to be by some of the contemporary philosophers 

 to whom the Epicureans " would not listen." But nothing less 

 than direct observation, proving Kepler's third law — Galileo's 

 experiment on bodies falling from the tower of Pisa, Boyle's 

 guinea-and-feather experiment, and Newton's experiment of the 

 vibrations of pendulums composed of different kinds of substance 

 — could either give the idea that gravity is proportional to mass, 

 or prove that it is so to a high degree of accuracy for large 

 bodies and small bodies, and for bodies of different kinds of 

 substance. Le Sage sums up his theory in an appendix to the 

 " Lucrece Newtonien," part of which, translated (literally, except 

 a few sentences which I have paraphrased), is as follows : — 



Constitution of Heavy Bodies, 



1st. Their indivisible particles are cages- — for example, empty 

 cubes or octahedrons vacant of matter except along the twelve 

 edges. 



2nd. The diameters of the bars of these cages, supposed in- 

 creased each by an amount equal to the diameter of one of the 

 gravific corpuscles, are so small relatively to the mutual distance 

 of the parallel bars of each cage, that the terrestrial globe does 

 not intercept even so much as a ten-thousandth part of the cor- 

 puscles which offer to traverse it. 



3rd. These diameters are all equal ; or if they are unequal, their 

 inequalities sensibly compensate one another [in averages] . 



Constitution of Gravific Corpuscules, 



1st. Conformably to the second of the preceding suppositions, 

 their diameters added to that of the bars is so small relatively to 



Y2 



