ENERGY AND ITS TRANSFORMATIONS. 



31 



the movement of electro-dynamic mechanism, this 

 energy is communicated to other machinery, and thus 

 caused to do work. 



Machinery of Transmission is used in the trans- 

 formation of energy suppHed by the prime mover into 

 available form, for the performance of special kinds of 

 work, or for simple transmission of power from the 

 prime mover to machines doing that work. 



II. The Sources of Energy, applied by man, 

 through the prime movers, to the economic purposes of 

 life, are six in number : 



(1) The potential energy of fuel, coming of the stor- 

 age, in early geological periods, of the actual energy of 

 the heat, light, and chemical forces of the sun's rays, 

 and the energy of the dispersing internal heat of the 

 earth, gathered up by the vegetation, and, in case of 

 the mineral oils, possibly, by the animal life, of those 

 primitive ages, reduced to this potential form and stored 

 in the depths of the earth for use in modern times. 

 Very possibly a still earlier history of this energy 

 may be traced in the gradual transformation of the 

 potential dynamic energy of a chaotic universe, in- 

 finitely dispersed, into the heat-energy of collision of 

 particle with particle, and of globe with globe, as the 

 existing systems of worlds took form. The potential 

 energy of fuel is converted by combustion into active 

 form. 



(2) The dynamic, the kinetic, energy of falling water, 

 transferred through water-wheels without transforma- 

 tion, to do useful work. 



This has a similar origin to the preceding ; the water 

 being raised from the seas, lakes, and streams to the 

 clouds by the action of the heat of the sun, thus carried 



