1855.] on Gravity. 11 



Newton's law, but go with him no further, that matter attracts 

 matter with a strength whicJi is inversely as the square of the 

 distance. Consider, then, a mass of matter (or a particle), for 

 which present purpose the sun will serve, and consider a globe like 

 one of the planets, as our earth, either created or taken from distant 

 space and placed near the sun as our earth is ; — the attraction of 

 gravity is then exerted, and we say that the sun attracts the earth, 

 and, also, that the earth attracts the sun. But if the sun attracts 

 the earth, that force of attraction must either arise because of the 

 presence of the earth near the sun ; or it must have pre-existed 

 in the sun when the earth was not there. If we consider the first 

 case, I think it will be exceedingly difficult to conceive that the 

 sudden presence of an earth, 95 millions of miles from the sun, and 

 having no previous physical connexion with it, nor any physical 

 connexion caused by the mere circumstance of juxtaposition, should 

 be able to raise up in the sun a power having no previous existence. 

 As respects gravity, the earth must be considered as inert, pre- 

 viously, as the sun ; and can have no more inducing or affecting 

 power over the sun than the sun over it : both are assumed to be 

 without power in the beginning of the case ; — how then can that 

 power arise by their mere approximation or co-existence ? That a 

 body without force should raise up force in a body at a distance 

 from it, is too hard to imagine ; but it is harder still, if that can 

 be possible, to accept the idea when we consider that it includes the 

 creation ofjorce. Force may be opposed by force, may be diverted, 

 directed partially or exclusively, may even be converted, as far as 

 we understand the matter, disappearing in one form to reappear in 

 another ; but it cannot be created or annihilated, or truly suspend- 

 ed, i.e. rendered existent without action or without its equivalent 

 action. The conservation of power is now a thought deeply im- 

 pressed upon the minds of philosophic men ; and I think that, as 

 a body, they admit that the creation or annihilation of force is 

 equally impossible with the creation or annihilation of matter. But 

 if we conceive the sun existing alone in space, exerting no force of 

 gravitation exterior to it ; and then conceive another sphere in 

 space having like conditions, and that the two are brought towards 

 each other ; if we assume, that by their mutual presence each 

 causes the other to act, — this is to assume not merely a creation 

 of power but a double creation, for both are supposed to rise from 

 a previously inert to a powerful state. On their dissociation they, 

 by the assumption, pass into the powerless slate again, and this 

 would be equivalent to the annihilation of force. It will be easily 

 understood, that the case of the sun or the earth, or of any one of 

 two or more acting bodies, is reciprocal ; — and also that the varia- 

 tion of attraction, with any degree of approach or separation of the 

 bodies, involves the same result of creation or annihilation of 

 power as the creation or annihilation (which latter is only the total 

 removal) of either of the acting bodies would do. 



