280 KINETIC THEORIES OF GRAVITATION. 



as the main business of natural philosophy is to argue from phenomena 

 without feigning hypotheses, and to deduce causes from effects, till we 

 come to the very first cause, which certainly is not mechanical."* 



It has already been noticed that elasticity has proved a stumbling- 

 block to every kinetic hypothesis. A system of molecular physics 

 without this property would represent a chaos ; but a chaos destitute 

 of energy. As Lame has well observed in his admirable treatise on the 

 subject, " The role of Elasticity in nature is as important as that of 

 Gravitation ! " How then are we to formulate this prime and potent 

 force? Evidently no phase or form of motion can simulate its action. 

 Here all kinetic theory fails: and there is then something in the world 

 beside " inertia and motion." Until some rational analysis be discov- 

 ered, we must accept the fact (in the language of Sir John Herschel) 

 as an "ultimate phenomenon." And as we find that the molecules of 

 all material substance resist compression with a force proportional in 

 some high ratio thereto, we can only conceive that they are separated 

 by an interval through which this repellant resistance is exercised. 

 Here then it seems, we are at once confronted with an "occult quality" 

 or virtue*, a force of repulsion, quite beyond the reach of any explana- 

 tion or relegation. And worse than all, with a quality or virtue which 

 proves to be that ever-dreaded and in fact "impossible" actio in dis- 

 tant! Are we then driven in the last resort to admit that devoid of all 

 perception of propriety, the insignificant physical molecule does pos- 

 itively "act where it is not," and where it ought not ? 



When we endeavor to penetrate into the secrets of molecular physics, 

 again are we borne on the waves of a large induction that the atoms of 

 matter never are and never can be in contact : but that in Seguin's 

 fine conception, they are really circulating in perpetual orbits of vary- 

 ing magnitude, according to the resultants of impulsions received by 

 mutual impacts on their dyuaspheres, or on the mystic boundaries of 

 their elastic repulsions: in orbits whose magnitude determines the 

 character of their aggregation, and which notwithstanding constant 

 perturbation, could be suppressed only by the total absorption of mo- 

 tion, in an absolute zero of temperature. And thus, whether we con- 

 template the infinitely small or the infinitely grand, in every case comes 

 back. upon us the wide induction, that the action of matter in atom, in 

 molecule, or in mass, is ever at a distance! Of actual contact there is 

 probably no instance afforded in nature, excepting in the intimate sub- 

 stance of the ultimate atom. And notwithstanding the petulant sneer 

 of some distinguished physicists, there is nothing to forbid (on the con- 

 trary much to favor) the Newtonian conception of infinitely hard spher- 

 ules of determinate magnitude, as the real substratum of the physical 

 universe. 



The assumption therefore of a material band or bar between bodies, to 

 transmit energy from one to another, whether by a pull or by a push, is 

 * Optics, Book iii, Query 28. 



