8 



THE ANIMAL AS A MACHINE. 



latent, the sum of which is constant throughout the 

 universe, energy is the source and the basis of all life, 

 of all motion, of all development, of all evolution. It 

 is the mainspring of all physical phenomena ; and the 

 science of Energetics is the foundation of chemistry, 

 as of physics ; of astronomy, as of the mechanics of en^ 

 gineering. Whatever we know of matter, even, is dis- 

 covered to us by these methods of display of energy in 

 connection with it. 



The science of energetics itself is one division of a 

 broader science, that of Mechanics, — that great science 

 which bears more or less directly upon every phenom- 

 enon of nature and the universe, and which is at the 

 foundation of all the applied sciences, of all the arts of 

 construction, of all the exact sciences of physics and 

 chemistry, of astronomy, and of forces and motions. 



4. Mechanics thus includes four principal divisions i"^ 



(1) Statics treats of the relations of forces acting in 

 any system when no motion results from that action. 



(2) Kinematics treats of the relations of motions sim- 

 ply, of their composition and resolution, and of their 

 resultant effects. 



(3) Dynamics or Kinetics treats of the motions pro- 

 duced in ponderable bodies by the action of forces. 



(4) Energetics treats of the measurement, the trans- 

 fer, and the transformations of energy under the action 

 of forces, and of their result in the variation of the 

 method of its manifestation. 



5. Energetics is defined, therefore, as that science 

 which treats of all natural phenomena which, through 



* Several pages are here taken mainly from "The Manual of the 

 Steam Engine," vol. i, by R. H. Thurston ; N. Y., J. Wiley & Sons. 



