168 Prof. Faraday on the Conservation of Force. 



amount at all these periods, though varying in their results. A 

 part may at the active moment be thrown otf as mechanical force, 

 a part as radiant force, a part disposed of we know not how ; 

 but believing, by the principle of conservation, that it is not 

 increased or destroyed, our thoughts are directed to search out 

 what at all and every period it is doing, and how it is to be 

 recognized and measured. A problem, founded on the physical 

 truth of nature, is stated, and, being stated, is on the way to its 

 solution. 



Those who admit the possibility of the common origin of all 

 physical force, and also acknowledge the principle of conserva- 

 tion, apply that principle to the sum total of the force. Though 

 the amount of mechanical force (using habitual language for 

 convenience sake) may remain unchanged and definite in its 

 character for a long time, yet when, as in the collision of two 

 equal inelastic bodies, it appears to be lost, they find it in the 

 form of heat ; and whether they admit that heat to be a con- 

 tinued mechanical action (as is most probable), or assume some 

 other idea, as that of electricity, or action of a heat-fluid, still 

 they hold to the principle of conservation by admitting that the 

 sum of force, i. e. of the " cause of action,'^ is the same, whatever 

 character the eflfects assume. With them the convertibility of 

 heat, electricity, magnetism, chemical action and motion is a 

 familiar thought ; neither can I perceive any reason why they 

 should be led to exclude, a priori, the cause of gravitation from 

 association with the cause of these other phsenomena respectively. 

 All that they are limited by in their various investigations, 

 ■whatever directions they may take, is the necessity of making 

 no assumption directly contradictory of the conservation of force 

 applied to the sum of all the forces concerned, and to endeavour 

 to discover the different directions in which the various parts of 

 the total force have been exerted. 



Those who admit separate forces inter-unchangeable, have to 

 show that each of these forces is separately subject to the 

 principle of conservation. If gravitation be such a separate 

 force, and yet its power in the action of two particles be sup- 

 posed to be diminished fourfold by doubling the distance, surely 

 some new action, having true gravitation character, and that 

 alone, ought to appear, for how else can the totality of the force 

 remain unchanged ? To define the force as " a simple attractive 

 force exerted between any two or all the ])articles of matter, 

 ■with a strength varying inversely as the square of the distance," 

 is not to answer the question ; nor does it indicate or even 

 assume what are the other complementary results which occur ; 

 or allow the supposition that such are necessary : it is simply, 

 as it appears to me, to deny the conservation of force. 



