lO 



THE ANIMAL AS A MACHINE. 



of elements, and no loss of matter ever takes place. 

 The persistence " of energy was a later discovery, con- 

 sequent largely upon the experimental determination of 

 the convertibility of heat-energy into other forms and 

 into mechanical work, for which we are indebted to 

 Rumford and Davy, and to the determination of the 

 quantivalence anticipated by Newton, shown and com- 

 puted approximately by Colding and Mayer, measured 

 with great accuracy by Joule and Rowland. 



It is now generally understood that all forms 

 of energy are mutually convertible with a definite 

 quantivalence ; and it is not certain that even vital 

 and mental energy do not fall within the same cate- 

 gory. 



The essentially important, as well as interesting, fact, 

 in this connection, to the engineer as well as to the 

 physicist, it should be noted, is that the laws of ener- 

 getics apply unqualifiedly to atomic and molecular 

 phenomena, as well as to energies of masses, and to all 

 transformations of energy in either class and of any 

 kind. There is, dynamically, absolutely no distinction, 

 in this respect, between the methods and processes of 

 chemistry, of physics, and of the mechanics of masses. 

 All illustrate phases of one science, and all are ener- 

 gies of matter in motion. 



6. Matter, Force, and Energy are the only quan- 

 tities known to the departments of natural science. 

 The science of Chemistry deals with the forms which 

 matter assumes under the action of measurable atomic 

 molecular forces affecting dissimilar kinds of matter ; 

 Physics is that science which deals with all the other 

 forms of sensible force and their effects. The science 

 of Energetics treats of the action of forces producing 



