ENERGY AND ITS TRANSFORMATIONS. 9 



the action of force upon matter, result in the produc- 

 tion of motion ; whether it be a relative motion of 

 atoms, of molecules, or of masses. It is that science 

 ''whose subjects are material bodies and physical phe- 

 nomena." We may here repeat : 



Energetics thus treats of modifications of energy 

 under the action of forces, and of its transformation 

 from one mode of manifestation to another, and from 

 one body to another ; and within this broader science 

 is comprehended that latest of the minor sciences — of 

 which the heat-engines and especially the steam-engine 

 illustrate the most important applications — Thermo- 

 dynamics. The science of energetics is simply a wider 

 generalization of principles which have been established 

 one at a time, and by philosophers widely separated, 

 both geographically and historically, by both space 

 and time, and which have been slowly aggregated, to 

 form one after another of the physical sciences, and 

 out of which we are slowly evolving wider generaliza- 

 tions ; thus tending toward a condition of scientific 

 knowledge which renders more and more probable the 

 truth of a principle, still broader than this science, 

 even, and which was enunciated before Science had a 

 birthplace or a name ; i.e. : 



All that exists^ whether matter or force y and in what- 

 ever form, is indestructible by any finite power. 



As already remarked, that matter is indestructible 

 by finite power became admitted as soon as the chem- 

 ists, led by Lavoisier, began to apply the balance, and 

 were thus able to show that in all chemical change there 

 occurs only a modification of form or of combination 



* Rankine ; Proc. Phil. Soc. Glasgow ; vol. iii. No. 6. 



