Dynamical Theories of Gravitation. 149 



On account of the relatively very large dimensions and 

 superior elastic rigidity of the gross molecule, it is scarcely 

 disturbed by the collision of the very minute atom. On the 

 other hand, the minute atom is thrown into strong vibration 

 and rotation by the blow. This vibration or rotation 

 (" internal motion ") cannot evidently be generated out of 

 nothing. The small atom therefore loses at impact a portion 

 of its transiatory motion, by converting the same into internal 

 motion (vibration and rotation). The diminution of the 

 transiatory motion of the small gravity-atoms at their en- 

 counter with gross molecules is therefore rather to be looked 

 upon as a necessary deduction than as an hypothesis. One 

 might, indeed, easily illustrate this fact experimentally. 



If an elementary example be excused, we can consider the 

 case when any small elastic body such as a small polished 

 steel key-ring is thrown against the surface of a polished steel 

 anvil. A key-ring and an anvil (of the same metal) may be 

 equally elastic, but on account of the considerable difference 

 in their dimensions — therefore pliability — only the small ring 

 will be thrown into perceptible vibration by the encounter 

 (or into rotation, for the anvil cannot rotate on account of its 

 mass). The ring rebounds with a diminution of its transiatory 

 motion, by converting the same into vibration and rotation. 



The atom gains its full transiatory motion gradually again 

 by collisions against atoms of its own kind, — from the fact 

 that the proportionality existing between the amount of trans- 

 iatory motion and the amount of internal motion of the atom 

 continually strives to maintain itself constant ; which is a 

 known consequence of the kinetic theory of gases, demon- 

 strated by Clausius. 



So is explained how the aether atoms, in being sifted through 

 gross matter, on the average lose a certain velocity of trans- 

 iatory motion, and that therefore a portion of gross matter 

 " shelters " any other neighbouring portion from the impacts 

 of the aether atoms. 



The penetration of the two masses by the flying aether atoms 

 brings about the fact that on the adjacent sides of the two 

 masses the pressure of the medium is smaller than on the remote 

 sides of the molecular surfaces of the two masses. The remote 

 sides encounter the full or undiminished transiatory velocity 

 of the atoms. Therefore the two masses are naturally driven 

 together, and with a force which obviously, from the nature 

 of the case, must be proportional to the square of the distance 

 of the masses. The further explanation of the gravitation 

 effect is then exactly as by Le Sage's theory. 



The present writer attempted in some papers, of which the 



