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IOWA ACADEMY OF SCIENCE Vol. XXVII, 1920 
gallons capacity at the Women’s Gymnasium, the other of 89,100 
gallons capacity at the Armory. Both are lined with white tile 
and located in light rooms. The women’s pool has a scum gutter 
entirely around the pool, while at the men’s pool the gutter is on 
the two sides and not on the ends. The water of both pools is 
continuously purified by passage through a filter. At the women’s 
pool the filter is a single-unit, open, gravity installation with a 
capacity of 138,240 gallons per 24 hours; at the men’s the ap- 
paratus is a two-unit, enclosed pressure filter of a capacity of 
116,000 gallons per day. Both plants employ aluminum sulphate 
as a coagulant. Filtered water is treated with 0.34 to 1.0 parts 
per million copper sulphate and 0.3 to 2.0 parts per million 
calcium hypochlorite. The dosage is varied according to the 
condition of the water in the pools. When the plants were in- 
stalled it was intended to use liquid chlorine for disinfection, 
but the apparatus secured did not give good results and finally 
had to be discarded on account of the difficulty of keeping it 
in repair. The men’s pool is kept at a temperature of 76° F., 
while the women’s pool runs up to 84° F. 
From the foregoing brief statement some idea of the operation 
of the pools may be obtained. More complete descriptions of the 
chemical equipment have been given elsewhere.^ 
Since the commencement of operations in January, 1916, samples 
have been taken every day that the pools have been in use. 
Sundays and holidays have been omitted as the pools have been 
closed at such times. 
Table No. 1, which summarizes the results from January 27, 
1916, to March 31, 1920, is the longest series of consecutive 
swimming pool results with which the writer is 'familiar. Table 
No. 2 gives the periods varying from 12 to 136 days elapsing 
between the times of filling and emptying. While some of these 
periods have been terminated by the failure of the water to 
respond to treatment, most of them have been determined by 
external factors, such as vacations, shortage of coal, need for the 
pool room for an S. A. T. C. dormitory and so on. 
Table No. 1 is a sort of frequency chart showing the number 
of days on which the bacterial counts fell within certain limits, 
and also showing the number of times gas-forming organisms 
were found in lactose broth and acid colonies on lactose agar. 
1 Hinman, Engineering and Contracting 46, 135 (Aug. 9, 1916). 
Hinman, Journal of the American Water Works Association, 4, 86 (March 1917). 
Hinman, American City (City Edition) 16, No. 4, 305 (April, 1918). 
Hinman, American Physical Education Review, December, 1920. 
