196 COMMISSION ON BUILDING DISTRICTS 



well as physical. The inherent difficulty at the present time is the absence of 

 scientific methods of measuring this positive element in health. Yet the 

 world knows as a matter of human experience that it is real and vital. The 

 expression, " health and comfort of the people," is centuries old, and these 

 two ideas are inseparable. 



Public health, of course, is the sum total of the health of the con- 

 stituent individuals. We measure public health inversely in terms of 

 death-rates because at present we have no means of measuring- health-rates. 

 We take a part as an index of the whole. 



Fundamental concepts 



Light, air, water, food and shelter are essential to life. Modern sani- 

 tarians would perhaps qualify this statement by adding the idea of cleanli- 

 ness, and say tbat clean air, clean water, clean food and clean human beings 

 are essential to healthy life. 



The regulation of buildings is intimately connected with the factors 

 mentioned — light, air, water, food, sanitation — and is therefore itself a 

 factor in public health. 

 Relation between internal and external conditions 



In cities people live an indoor life to a greater extent than they live 

 out-of-doors. During the last fifty years cities have increased greatly in 

 size and indoor life has become correspondingly more common and more 

 important. The advent of steel construction has changed the shape of 

 many buildings, increasing height and producing congestion. It has also 

 had a tendency to reduce the size of rooms and lias led to what is termed 

 a cellular type of housing for dwellings and offices. 



As far as health is concerned indoor conditions are on the whole more, 

 important than outdoor conditions in a city like New York. Indoor con- 

 ditions are dependent largely upon the plan and construction of buildings 

 and upon occupancy, all of which are well recognized as coming within 

 the control of the police power. But indoor conditions are also and to a 

 large extent controlled by the conditions out-of-doors. It is the outside en- 

 vironmental conditions to which the tentative regulations of the Commis- 

 sion are chiefly directed. The amount of daylight which enters a building 

 depends upon the amount of sunlight which falls upon the exterior, and 

 upon the proximity of other buildings, their height, and their bulk. The 

 amount of air which enters a building is also influenced, and sometimes very 

 greatly, by the surrounding buildings. The purity of the air is likewise 

 affected by outside conditions. Thus while spoken of, and properly so, 

 as the regulation of buildings it is the regulation of the space between 

 buildings which is the object in view, a system of regulations designed to 

 prevent one lot owner from interfering with the light and air required by 

 his neighbor. While in general rights in the use of land are bounded by 

 vertical planes, it must not be forgotten that the sun's ravs fall slantingly 

 upon the land while the wind movements are chiefly horizontal. These 

 natural elements are interfered with by excessive high and crowded build- 

 ings, hence there are rights in land ownership which extend beyond the 

 vertical planes. 



The following are some of the points to be considered in connection with 

 this subject. 



Sunlight 



The rays of the sun bring light and heat to the earth and both are 

 absolutely necessary to man's existence. Considered from the standpoint 



