Water Pressure.
Ten feet head of water gives a pressure of 4⅓ lbs. per square inch approximately.
If H = head of water in feet, P = pounds pressure per square inch:
H = P × 2·311 P = H × ·4326
Horse-power required to Pump Water.—One h.-p. indicated will raise about 3000 gallons of water per hour 50 feet high.
To pump 1 gallon of water per minute against a pressure of 4 lb. per square inch, requires:
p × ·0007 H.-P.
BORING.
Rock is bored with jumpers of 10 lb. to 18 lb., used alone, or with boring bars and hammer. The former are more effective, but can only be used perpendicularly, or nearly so, and with rock of moderate hardness; they require more skill.