452 On the Conservation of Force. [1857. 



gential balance as to act independent of the gravitating force. 

 It has the like strict relation to force communicated by im- 

 pact, pull, or in any other way. It enables a body to take up 

 and conserve a given amount of force until that force is trans- 

 ferred to other bodies, or changed into an equivalent of some 

 other form ; that is all that we perceive in it : and we cannot 

 find a more striking instance amongst natural or possible phe- 

 nomena of the necessity of the conservation of force as a law 

 of nature ; or one more in contrast with the assumed variable 

 condition of the gravitating force supposed to reside in the 

 particles of matter. 



Even gravity itself furnishes the strictest proof of the con- 

 servation of force in this, that its power is unchangeable for 

 the same distance ; and is by that in striking contrast with the 

 variation which we assume in regard to the cause of gravity, 

 to account for the results at different distances. 



It will not be imagined for a moment that I am opposed to 

 what may be called the law of gravitating action, that is, the 

 law by which all the known effects of gravity are governed ; 

 what I am considering, is the definition of the force of gravi- 

 tation. That the result of one exercise of a power may be 

 inversely as the square of the distance, I believe and admit ; 

 and I know that it is so in the case of gravity, and has been 

 verified to an extent that could hardly have been within the 

 conception even of Newton himself when he gave utterance to 

 the law : but that the totality of an inherent force can be em- 

 ployed according to that law I do not believe, either in rela- 

 tion to gravitation, or electricity, or magnetism, or any other 

 supposed form of power. 



I might have drawn reasons for urging a continual recollec- 

 tion of, and reference to, the principle of the conservation of 

 force from other forms of power than that of gravitation ; but 

 I think that when founded on gravitating phenomena, they 

 appear in their greatest simplicity ; and precisely for this rea- 

 son, that gravitation has not yet been connected by any degree 

 of convertibility with the other forms of force. If I refer for a 

 few minutes to these other forms, it is only to point in their 

 variations, to the proofs of the value of the principle laid down, 

 the consistency of the known phenomena with it, and the sug- 



