Vienna | 1,365,000 | 20 St. Petersburg | 960,000 | 40 Bombay | 810,000 | 61 Sidney | 423,600 | 38 Buenos Ayres | 680,000 | 34 ---------------------------------------+-------------+----------- [5] Compiled, except the figures for London, by Hazen. _Engineering News_, 1899, XLI. p. 111. These foreign averages, with three exceptions, represent reasonable quantities of water used, and they have been confirmed as reasonable by many special investigations made in this country. =153. Variations in Rate of Daily Consumption.=—The preceding observations are all based upon an average total consumption found by dividing the total annual consumption by the number of days in the year. This is obviously sufficient in a determination of the total supply needed, but it is not sufficient in those matters which involve a rate of supply during the different hours of the day, or the amount of the supply for the summer months as compared with those of the winter. As a general rule the greatest supply will be required during the hot summer months when lawn- and street-sprinkling is most active. It appears from observations made in a considerable number of the large cities of the United States that the maximum monthly average consumption may run from about 110 to nearly 140 per cent of the monthly average throughout the year. As an approximate value only, it may be assumed for ordinary purposes that the maximum monthly demand will be 125 per cent of the average.