ENERGY IN GENERAL. 59 



As for energetics, of which thermodynamics is only 

 a section, it is agreed that even if it cannot forthwith 

 absorb mechanics, astronomy, physics, chemistry, and 

 physiology, and build up that general science which 

 will be in the future the one and only science of 

 nature, it furnishes a preparation for that ideal state, 

 and is a first step in the ascent to definite progress. 



Here I propose to expound these new ideas, in so 

 far as they contain anything universally accessible; 

 and in the second place, I propose to show their 

 application to physiology — that is to say, to point out 

 their role and their influence in the phenomena of 

 life. 



Postulate: the Phenomena of Nature bring into 

 play only two Elements, Matter and Energy. — If we 

 try to account for the phenomena of the universe, 

 we must admit with most physicists that they 

 bring into play two elements, and two elements only 

 namely, matter and energy. All manifestations are 

 exhibited in one or other of these two forms. This, 

 we may say, is the postulate of experimental science. 



Just as gold, lead, oxygen, the metalloids, and the 

 metals are different kinds of matter, so it has been 

 recognized that sound, light, heat, and generally, the 

 imponderable agents of the days of early physics, are 



to set the planetary system on its path when disturbed by ac- 

 cumulated perturbations. On the other hand, Colding claims to 

 have drawn his knowledge of the law of conservation from 

 d'Alembert's principle. Whatever may be the theoretical 

 foundations of this law, we are here dealing with its experi- 

 mental proof. According to Tait, the proof can no more be 

 attributed to R. Mayer than to Seguin. The real modern 

 authors of the principle of the conservation of energy, who gave 

 an experimental proof of it, are Colding, of Copenhagen, and 

 Joule, of Manchester. 



