PERMANENCE OF ENERGY 



knowledge and science rest. By their help only can 

 the Path of Evolution ever be more fully known. 

 These results have been obtained, not through 

 deductive reasoning from a-priori ideas or assumed 

 premises, but by careful observation and repeated 

 experiment. They have shown that when any 

 form of energy, such as the motion of translation 

 of a mass of molecular matter, or when that motion 

 which constitutes heat, light, electricity or chemical 

 action disappears, it is not lost, but reappears in one 

 or more other forms, bearing an exact and definite 

 ratio to the quantity of the force expended. Thus, 

 when a mass of 772 pounds falls to the earth from 

 the height of one foot, its arrest evolves as much heat 

 as would raise the temperature of one pound of water 

 one degree F. ; conversely, one pound of water in 

 falling one degree in temperature will give off heat 

 enough to raise 772 pounds one foot high. This 

 relation of heat, height and weight is used as the con- 

 stant under the name of " foot-pounds " with which 

 to measure not only heat, weight and motion, but 

 also as the standard with which to compare all other 

 changes of energy. 



It has been shown that all energy, or the mani- 

 festation of all physical force on the globe is derived 

 directly or indirectly from the radiation of heat and 

 of light from the sun. All physical motion, for 

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