AMOUNT OF SEWAGE PER CAPITA 137 



be called nothing, and the flow for the rest of the day reduced 

 correspondingly. 



Fig. 42 shows three curves based on gagings made of the 

 two main sewers of the small city of Cadillac, Mich. The lower 

 curve is for the 1 2-inch main, serving 475 persons. The middle 

 curve is for the i8-inch main, serving 2517 persons. The 

 upper curve is the result of adding together the measurements 

 in these two sewers but correcting for the discharge of thirteen 

 flush-tanks. The 1 2-inch pipe, without flush- tank water, had 

 a minimum flow of 221 gallons, an average of 318 and a max- 

 imum of 558, the latter being 75 per cent greater than the 

 average even with the high minimum flow. For the 1 8-inch 

 pipe the minimum rate was 138 gallons, the average, 178, 

 and the maximum, 239, or 34 per cent above the average. 

 The large flow is said to be due almost wholly to defective 

 plumbing, and the results are interesting as indicating the large 

 amount of waste in a relatively small place. 



Fig. 43* shows a long-time measurement of the flow of 

 sewage in the intercepting sewer at Gloversville. The large 

 flows in the spring of both years is undoubtedly due to ground- 

 water entering the pipes, although the system is intended 

 strictly for house sewage only. The minor variations from day 

 to day are very marked and the excess in March is plainly 

 responsible for a flow more than double the average. 



Fig. 44, also of Gloversville, shows the hourly variation for 

 a typical day. The effect of the mill wastes is most striking 

 and serves, in this city at any rate, to show that the high night 

 flow of sewage is not due to manufacturing use. 



For the sewage alone, the average hourly rate was 62,000 

 gallons and the maximum 78,000, or 26 per cent increase. 

 With the mill wastes added, the average flow is 84,000 gallons 

 and the maximum 119,000, an excess of 42 per cent. 



It follows from a study of the tables and diagrams given 

 above that while the amount of flow or the per capita flow 

 varies between wide limits, affected largely by the amount of 



* Report of Harrison P. Eddy and Morrell Vrooman to Mayor of Gloversville. 



