104 SEWER DESIGN 



In the design of sewers for the place, Mr. Hering assumes the 

 future population as 30,000, not stating, however, when this 

 number is to be expected. The actual population by the 1910 

 Census was 14,802. 



The result of this study into methods of forecasting the 

 population of any city at some definite future time is that it 

 is a matter for the judgment of the engineer. That while he 

 may make use of certain auxiliaries, such as census reports 

 for past growth and for the growth of other cities, while he 

 may consult the local reports of growth in various municipal 

 directions, while he may construct diagrams and tables, these 

 are all only aids. The actual determination of the future 

 population must be made by the individual judgment, based 

 and guided by such methods as have been outlined, but modified 

 by an intimate knowledge of the local conditions of situation 

 and enterprise, and of the other often unknown factors which 

 govern the growth of a modern city. 



PROBLEMS 



37. By reference to the publications of the U. S. Census Bureau, 

 find the average numbers of persons per house in five cities of New York 

 State. Choose cities differing in location, size, and kind of industry. 



38. Collect records of population as given by U. S. Census Bureau 

 for years 1860-1910 inclusive for City of Rochester, N. Y., and by plotting 

 the curve of its growth, estimate the probable population for 1950. 



39. Take a city directory for 1900, and by comparing the 



number of names with the census population, get the ratio of names to 

 total population. Multiply the number of names in the 1910 directory 

 by this ratio and compare the result with the census population. 



40. Using census populations for 1900 and 1910 for the city of , 



compute the annual ratios, assuming both an arithmetical and geometrical 

 law of increase. Using both ratios determine the populations for 1005 

 and for 1915. 



41. Find the probable population of Elmira in 1950, by comparing 

 with population of Syracuse, Rochester, Cambridge, Lowell, and Newark, 

 after method of Fig. 20. 



