60 PUBLIC HEALTH 



that the proper care and right use of the individual human mechan- 

 ism reacts favorably and fundamentally upon the public health 

 no less truly or effectively than an improved condition of the en- 

 vironment or of the public health tends to promote the welfare 

 and long life of the individual. 



The sphere of hygiene may be divided, as it often is, into the 

 two hemispheres, public hygiene and personal hygiene, or it may 

 be cut into one portion dealing chiefly with the human mechanism 

 and its operation (personal hygiene), and another portion dealing 

 chiefly with the environment of that mechanism (sanitation). The 

 time has gone by when any one person can safely undertake to deal 

 with the whole sphere of hygiene. The physiologist and the phy- 

 sician must in the future leave to the architect and the sanitary 

 engineer such subjects as housing, heating and ventilation, water- 

 supply and sewerage, precisely as the sanitary engineer has never 

 presumed to deal with foods and feeding, vaccines and antitoxins, 

 exercise, sleep, and rest. The former subjects deal chiefly with the 

 control of the environment, the latter subjects chiefly with the con- 

 trol of the individual, and sanitation and hygiene must hencefor- 

 ward be regarded as separate hemispheres of the science of health. 



The science of architecture, if under this head we include the 

 principles of building construction, and the heating and ventila- 

 tion of buildings, has done and is doing much of interest and im- 

 portance to the student of public health science. For my own part, 

 I am continually more and more impressed with the fact that the 

 air-supply, especially for the modern civilized and too often seden- 

 tary form of mankind, is in the long run quite as important as the 

 water-supply, the milk-supply, or any other supply. Surely, we can- 

 not be too careful of the purity of a substance which we take into 

 our bodies oftener, and in larger volume, than any other, and which 

 has come, rightly, no doubt, and as the result of long and painful 

 experience, to be known as the very breath of life. I am well aware 

 that human beings may survive and seemingly thrive, even for long 

 periods, in bad air, but I am certain that for the best work, the 

 highest efficiency, the greatest happiness, and the largest life, as well 

 as for perfect health, the very best atmosphere is none too good. 

 Hence I believe that the permeability of the walls of houses and 

 other buildings, and the heating and ventilation of dwellings, 

 school-houses, churches, halls, and other public places, require, 

 and in the near future will receive, a much larger share of our 

 attention than they have to-day. 



In an age characterized by urban life and possessing sky-scrapers, 

 tenement-houses, and other huge beehives, in which human beings 

 aggregating vast numbers spend a large part of their lives, build- 

 ings require for their proper construction, lighting, heating, air- 



