Unity of the General Forces of Nature. lYl 



into any one of these pbeiiomeua of motion. Being wliolly 

 internal, it is ineapable of passing out into the spaces beyond 

 the volnme of the atom whose existence it preserves. It 

 exists unchanged throngh motion and rest alike, and, posses- 

 sing uo relation to motion, is inconvertible into any form 

 of it, either molecular or mechanical. Its sole function is 

 to maintain the existence and reality of the atom which it 

 permeates, as a permanent, indestructible and, therefore, 

 inconvertible thino". 



That form of force, then, which has for its exclusive func- 

 tion to guarantee the indestructibility of matter, must be 

 conceived as sid generis, — as wholly peculiar, incommuni- 

 cable to anything else, and inconvertible with any other 

 form of force in the universe. We must, therefore, recog- 

 nize the reality of one force, at least, which is incapable of 

 transmutation into any other. 



Moreover, this peculiar and inconvertible force is also in- 

 capable of correlation. It cannot be converted, cither into 

 any other force directly, or into that mechanical motion 

 Avhich is the common measure of all the others. We cannot 

 express this resistance in terms of any other denomination. 

 We cannot say that it is equivalent to a given amount of heat, 

 nor can we assign the number of foot-pounds which will 

 measure the ultimate resistance of an atom to compression. 

 As destitute of all relation to motion, it is out of all relation 

 to those forces which express and measure themselves by 

 motion. It simply cannot take the form of light, or heat, or 

 electricity ; a greater degree of heat is as incapable of ex- 

 pressing the intensity of this force, as a less would be. It 

 stands outside of the sphere within which the correlation of 

 the forces finds its scope ; and being necessarily out of all 

 relation with the others, it is of course incapable of corre- 

 lation with them. 



It follows that the doctrine of the convertibility of the 

 forces relates properly only to those general and diffused 

 forces of nature which impart motion; and not, so to speak, 



