26 



GENERAL SCIENCE 



activities and labors are performed. Energy is often denned 

 as that by use of which work is done. Any machine such as 

 an engine, is only a means employed for using energy to do 

 work. The human body comes under this definition, and 

 this conception of the body includes brain activities as well 

 as muscular effort. 



The human body as a living organism possesses, however, 

 the power of repairing itself under right conditions of liv- 

 ing. If properly cared for, it should 

 neither break down nor wear out till long 

 past the allotted "three score years and 

 ten." As with any other engine the 

 character and quantity of work it can do 

 depends in large measure upon the care it 

 has, and the good judgment exercised 

 in its use. Folly, ignorance, and inex- 

 perience all combine to impair its use- 

 fulness or to wreck it altogether. It is 

 one of the purposes of schools to give in- 

 struction and training in the right uses 

 as a machine may of both body and mind. Success in living 



break down rather ... 



than wear out. even as success in business requires the 



best use of all the means and machinery 

 of life. It is necessary for the well-being of an individual that 

 the bodily processes be under as intelligent control and as 

 constant care as that exercised by an engineer with a locomo- 

 tive, or by a chemist in laboratory experiments. 



The body like the steam engine depends upon energy lib- 

 erated within it by chemical changes. A considerable por- 

 tion of this energy is used in keeping up the bodily processes. 

 The activities of the heart, digestive organs, brain," and other 

 organs require an expenditure of energy. Deficiency in 

 its amount means imperfect performance or complete ces- 

 sation in their activities. It is chiefly the starchy foods, 



FIG. 12. The body 



