Doubling the diameter of a pipe increases its capacity four times. Friction of liquids in pipes increases as the square of the velocity.

The mean pressure of the atmosphere is usually estimated at 14.7 pounds per square inch, so that with a perfect vacuum it will sustain a column of mercury 29.9 inches or a column of water 33.9 feet high.

‘To find the pressure in pounds per square inch, in a column of water, multiply the height of the column in feet by .434. Approximately, we say that every foot elevation is equal to one-half pound pressure per square inch; this allows for ordinary friction.

“To find the diameter of a pump cylinder to move a given quantity of water per minute (IOO feet of piston being the standard of speed), divide the number of gallons by 4, then extract the square root, and the product will be the diameter in inches of the pump cylinder.

To find the quantity of water elevated in one minute running at 100 feet of piston speed per minute, square the diameter of the water cylinder in inches and multiply by 4. Example: Capacity of a fiveinch cylinder is desired. The square of the diameter (five inches) is twenty-five, which, multiplied by 4, gives 100, the number of gallons per minute (approximately).

To find the horse power necessary to elevate water to a given height, multiply the total weight of the water in pounds by the height in feet, and divide the product by 33,000 (An allowance of twenty-five per cent, should be added for water friction, and a further allowance of twenty-five per cent, for loss in steam cylinder.)

The area of the steam piston multiplied by the steam pressure gives the total amount of pressure that can be exerted. The area of the water piston multiplied by the pressure of water per square inch, gives the resistance. A margin must be made between the power and resistance to move the pistons at the required speed, say from twenty to forty per cent., according to speed and other conditions.

To find the capacity of a cylinder in gallons. Multiplying the area in inches by the length of stroke in inches will give the total number of cubic inches, divide this amount by 231 (which is the cubical contents of a United States gallon in inches), and product is the capacity in gallons.

To find the number of gallons in a tank, multiply the inside bottom diameter in inches by the inside top diameter in inches then this product by 34; point off four figures, and the result will be the average number of gallons to one inch in depth of the tank.

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