358 Mr. Faraday [Feb. 27, 



denying, it opposes a dogmatic barrier to improvement ; by ignoring, 

 it becomes in many respects an inert thing, often much in the way ; 

 by admitting, it rises to the dignity of a stimulus to investigation, a 

 pilot to human science. 



The principle of the conservation of force would lead us to 

 assume, that when A and B attract each other less because of in- 

 creasing distance, then some other exertion of power, either within 

 or without them, is proportionately growing up ; and again, that 

 when their distance is diminished, as from 10 to 1, the power of 

 attraction, now increased a hundred-fold, has been produced out of 

 some other form of power which has been equivalently reduced. 

 This enlarged assumption of the nature of gravity is not more 

 metaphysical than the half assumption ; and is, I believe, more 

 philosophical, and more in accordance with all physical considera- 

 tions. The half assumption is, in my view of the matter, more 

 dogmatic and irrational than the whole, because it leaves it to be 

 understood, that power can be created and destroyed almost at 

 pleasure. 



When the equivalents of the various forms of force, as far as 

 they are known, are considered, their differences appear very great ; 

 thus, a grain of water is known to have electric relations equivalent 

 to a very powerful flash of lightning. It may therefore be supposed 

 that a very large apparent amount of the force causing the pheno- 

 mena of gravitation, may be the equivalent of a very small change 

 in some unknown condition of the bodies, whose attraction is 

 varying by change of distance. For my own part, many consider- 

 ations urge my mind toward the idea of a cause of gravity, which 

 is not resident in the particles of matter merely, but constantly in 

 them, and all space. I have already put forth considerations re- 

 garding gravity which partake of this idea,* and it seems to have 

 been unhesitatingly accepted by Newton.f 



There is one wonderful condition of matter, perhaps its only 

 true indication, namely inertia; but in relation to the ordinary 

 definition of gravity, it only adds to the difficulty. For if we con- 

 sider two particles of matter at a certain distance apart, attracting 

 each other under the power of gravity and free to approach, they 

 will approach ; and when at only half the distance each will have had 

 stored up in it, because of its inertia^ a certain amount of mechani- 

 cal force. This must be due to the force exerted, and, if the con- 



* Proceedings of the Royal Institution, 1855, Vol. ii., p. 10, &c. 



t " That gravity should be innate, inherent, and essential to matter, so that 

 one body may act upon another at a distance, through a vacuum, without the 

 mediation of any thing else, by and through which their action and force may 

 be conveyed from one to another, is to me so great an absurdity that I believe 

 no man who has in philosophical matters a competent faculty of thinking, can 

 ever fall into it. Gravity must be caused by an agent, acting constantly accord- 

 ing to certain laws ; but whether this agent be material or immaterial I have 

 left to the consideration of my readers."-»SeeiVcM>/on'« Third Letter to BentUy. 



