6.3 inches. From all this we find that a rain-water tank should hold at least 4th of the annual rainfall. Thus, with 24 inches, or 2 feet per year, a building 1830 square feet in area, collects 1830 x 2 = 3660 cubic feet, allowing a consumption of 10 cubic feet, or 62.3 gallons per day, and the tank should hold 3660÷ 915 cubic feet. 4 = (88.) "Weight and Pressure of Water."-A gallon of water at 62° weighs 10 lbs., and contains 277 274 cubic inches, or 16046 cubic foot: hence a cubic foot weighs 62 321 lbs., and contains 6.2321, or nearly 61 gallons. Table 28 gives the pressure in pounds per square inch due to given columns of water and mercury. TABLE 28.-Of EQUIVALENT PRESSURES in POUNDS per SQUARE INCH, FEET of WATER, and INCHES of MERCURY, at a Temperature of 62° Fahr. EXAMPLE.-Required the Pressure per Square Inch, and Equivalent Column of Mercury for a Head of 247 feet of Water. LONDON: PRINTED BY WILLIAM CLOWES AND SONS, LIMITED, STAMFORD STREET AND CHARING CROSS. |