THE CONTROL OF HEALTH 385 



It is secured by keeping surface water away from foundation 

 walls by tight bottom construction, and by a drainage exit 

 for any water which may enter in unanticipated ways. 



The side walls of a building are much warmer if made in at 

 least two thicknesses (preferably three) with an air space 

 between. This same method of insulation against a tempera- 

 ture change is used in the construction of refrigerators and 

 incubators, where maximum uniformity in temperature is 

 wanted. Windows should be numerous, both for purposes of 

 light entrance and for ventilation. The doors as well as the 

 windows should be fitted with screens so that insects may be 

 kept out, as some of these are now well known carriers of 

 numerous kinds of disease ' 'germs" (bacteria). 



Walls and floors of rooms should be so finished as to be 

 easily kept free from dirt and dust. Fancy wood-work in 

 which dust collects and which is cleaned with difficulty, is 

 unhygienic. 



Location with Reference to Light and Air. - - Whether 

 in city or country, one should keep in mind the need of adequate 

 light and the vital necessity of plenty of pure air when deciding 

 on a place of residence. Dense shade from trees or an environ- 

 ment of high buildings makes the eyes work under difficulties, 

 necessitates the expense of artificial light, and constitutes a 

 condition of general unwholesomeness. This is because sun- 

 light is one of the most effective agents in the destruction of 

 bacteria. Sunny rooms are not merely well lighted, but are 

 healthful. This germicidal action of light should be utilized 

 by putting clothing, rugs, and house-furnishings in the open 

 air on sunny days. 



Artificial Light. Of the modern methods of artificial 

 lighting, electricity is by far the most convenient and hygienic. 

 Its convenience is obvious, and its use is hygienic because 

 there is no leakage or odor as with gas or oil lighting. Electric 

 lighting systems have now been developed so that a home in 

 the country may be lighted by electricity. 



