CHAPTER XV 



THE SOURCE AND NATURE OF VITAL ENERGY 

 MATTER AND ENERGY 



PHYSICAL science teaches that the universe consists of twc* 

 great factors, matter and energy. 



MATTER 



By matter is meant the substance of the objects found in 

 nature, such as earth, stones, etc. One of the fundamental laws 

 of physics is that, while matter may be changed from one form 

 to another, it can neither be created nor destroyed. The amount 

 of matter in the universe at the present time is thus exactly 

 the same as it has been in all previous ages. 



ENERGY 



By energy is meant the force or power that exists in nature. 

 Energy is the power of doing work, and may best be explained 

 by illustrations. 



Active Energy. A cannon ball flying through the air is said 

 to possess energy. It is flying with such force and momentum 

 that it requires great resistance to stop it; and if the ball could 

 be received upon properly devised machinery, its motion might 

 be made to turn wheels or do any other kind of work. The 

 revolving flywheel of an engine also possesses energy of the 

 same type, its motion and its great momentum enabling it, if 

 connected with machines, to move them and make them do 

 work. In the same way, any form of motion is energy. In 

 another type of energy the motion is not so evident. Heat, 

 liberated from burning coal, is energy, since, when it is properly- 

 applied to an engine, it may be made to do work. In this case 

 the heat may be applied to water, which it vaporizes into steam, 

 and this eventually may produce motion in an engine; but it 



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