ENERGY IN GENERAL- 89 



energy. It is a state of the ether of a peculiar, 

 specific kind, periodically produced (electric oscilla- 

 tion), and propagated with a speed of the order of 

 that of light. 



However that may be, what constitutes the essential 

 peculiarity of electrical energy, and what causes its 

 value, is that it is an incomparable agent of trans- 

 formation. Every known form of energy may be 

 converted into it, and inversely, electrical energy may 

 be changed with the utmost facility into all other 

 energies. This extreme adaptability assigns to it 

 the part of an intermediary between the other less 

 tractable agents. Mechanical energy, for instance, 

 lends itself with difficulty to the production of light, 

 that is to say, to a metamorphosis into photic energy 

 (a variety of thermal energy). A fall of water cannot 

 be directly utilized for lighting purposes. The 

 mechanical work of this fall, which cannot be 

 exploited in its present form, serves to set in 

 motion in industrial lighting the installations, the 

 electric machines, and the dynamos which feed the 

 incandescent lamps. Mechanical work is changed 

 into electrical energy, and it, in its turn, into thermal 

 or photic energy. Electricity has here played the part 

 of a useful intermediary. 



The last part of energetics must be consecrated to 

 the study of the general principles of this science. 

 These principles are two hi number, the principle of 

 the conservation of energy, or Mayer's principle, and 

 the principle of the transformation of energy, or 

 Carnot's principle. The doctrine of energy thus 

 reduces to two fundamental laws the multitude of 

 laws, often known as "general," to which natural 

 science is subject. 



