AT OUR HOMES 219 



pensable in the industries and in commerce. The heat liberated from 

 it may be considered solar energy stored during the centuries of a 

 remote past. 



It was not till about 1880 that the "incandescent" light with its 

 carbon filaments within an exhausted glass bulb, perfected by Thomas 

 A. Edison (1847 )> became a commercial success. The extended 

 use of the powerful arc lights for out-of-door illumination waited upon 

 the development of the dynamo to maintain sufficient strength of 

 current through long periods of time at relatively low cost. 



SOME FOODSTUFFS 



There is much more to any consideration of what one shall 

 eat and what one shall drink than is involved in its market 

 price as part of the cost of living, and its purity and whole- 

 someness as these affect one's health. How much to eat 

 (or how little), and the relative amounts of the different 

 foods 1 in order to give a balanced ration, are too often given 

 scant attention till ill-health and its limitations make orders 

 from the physician imperative. 



A person's appetite naturally is not only nature's warning 

 of need- for food by the body, but under normal conditions 

 it should serve as a guide in choice of the foods best suited 

 to meet these body needs. That which is appetizing, and 

 for which one has great relish, is in general good for one. 

 Unfortunately the appetite may become perverted or dulled, 

 and its guidance alone is always unsafe. The use of any 

 food or drink that creates a craving, and which demands more 

 and more use of it (any " habit- forming " substance), is 

 always to be shunned. One should never eat beyond his 

 ability to fully digest what is eaten. Any meal is sufficient 



1 The term food as used here and later is to be distinguished from "food- 

 stuffs" as sold in the market, and the various " dishes" served at table for our 

 meals. It has reference to the groups of chemical compounds named on 

 page 222. 



