Centimeter = 0.3937 inch Meter = 3.28 feet Meter = 1.094 yards Kilometer = 0.621 statute mile Kilometer = 0.5396 nautical mile Inch = 2.540 centimeters Foot = 0.305 meter Yard = 0.914 meter Statute mile = 1.61 kilometers Nautical mile = 1.853 kilometers

AREA.

Sq. centimeter = 0.155 sq. inch Sq. meter = 10.76 sq. feet Sq. meter = 1.196 sq. yards Hectare = 2.47 acres Sq. kilometer = 0.386 sq. mile Sq. inch = 6.45 sq. centimeters Sq. foot = 0.0929 sq. meter Sq. yard = 0.836 sq. meter Acre = 0.405 hectare Sq. mile = 2.59 sq. kilometers

WEIGHT.

Gram = 15.43 grains Gram = 0.772 U. S. apoth. scruple Gram = 0.2572 U. S. apoth. dram Gram = 0.0353 avoir. ounce Gram = 0.03215 troy ounce Kilogram = 2.205 avoir. pounds Kilogram = 2.679 troy pounds Metric ton = 0.984 gross or long ton Metric ton = 1.102 short or net tons Grain = 0.064 gram U. S. apoth. scruple = 1.296 grams U. S. apoth. dram = 3.89 grams Avoir. ounce = 28.35 grams Troy ounce = 31.10 grams Avoir. pound = 0.4536 kilogram Troy pound = 0.373 kilogram Gross or long ton = 1.016 metric tons Short or net ton = 0.907 metric ton

VOLUME.

Cu. centimeter = 0.0610 cu. inch Cu. meter = 35.3 cu. feet Cu. meter = 1.308 cu. yards Cu. inch = 16.39 cu. centimeters Cu. foot = 0.283 cu. meter Cu. yard = 0.765 cu. meter

CAPACITY.

Millimeter = 0.0338 U. S. liq. ounce Millimeter = 0.2705 U. S. apoth. dram Liter = 1.057 U. S. liq. quarts Liter = 0.2642 U. S. liq. gallon Liter = 0.908 U. S. dry quart Dekaliter = 1.135 U. S. pecks Hectoliter = 2.838 U. S. bushels U. S. liq. ounce = 29.57 millimeters U. S. apoth. dram = 3.70 millimeters U. S. liq. quarts = 0.946 liter U. S. dry quarts = 1.101 liters U. S. liq. gallon = 3.785 liters U. S. peck = 0.881 dekaliter U. S. bushel = 0.3524 hectoliter

AVOIRDUPOIS WEIGHT.

1 pound = 16 ounces = 256 drams 1 ounce = 16 "

TROY (APOTHECARIES') WEIGHT (U. S.)

1 pound = 12 ounces = 96 drams = 288 scruples = 5,760 grains 1 ounce = 8 drams = 24 scruples = 480 grains 1 dram = 3 scruples = 60 grains 1 scruple = 20 grains

WINE (APOTHECARIES) LIQUID MEASURE (U. S.)

1 gallon = 8 pints = 128 fl. ozs. = 1,024 fl. drams = 61,440 minims 1 pint = 16 fl. ozs. = 128 fl. drams = 7,689 minims 1 fl. oz. = 8 fl. drams = 480 minims 1 fl. dram = 60 minims

_To find diameter of a circle_ multiply circ.u.mference by .31831.

_To find circ.u.mference of a circle_, multiply diameter by 3.1416.

_To find area of a circle_, multiply square of diameter by .7854.

_To find surface of a ball_, multiply square of diameter by 3.1416.

_To find side of an equal square_, multiply diameter by .8862.

_To find cubic inches in a ball_, multiply cube of diameter by .5236.

_Doubling the diameter of a pipe_, increases its capacity four times.

_One cubic foot of anthracite coal_ weighs about 53 lbs.

_One cubic foot of bituminous coal_ weighs from 47 to 50 pounds.

_A gallon of water_ (U. S. standard) weighs 8-1/3 pounds and contains 231 cubic inches.

_A cubic foot of water_ contains 7-1/2 gallons, 1728 cubic inches and weighs 62-1/2 pounds.

_To find the number of pounds of water a cylindrical_ tank contains, square the diameter, multiply by .785 and then by the height in feet.

This gives the number of cubic feet which multiplied by 62-1/2 gives the capacity in pounds of water. Divide by 7-1/2 and this gives the capacity in gallons.

_A horse-power_ is equivalent to raising 33,000 pounds 1 foot per minute, or 550 pounds 1 foot per second.

_The friction of water in pipes_ is as the square of velocity. The capacity of pipes is as the square of their diameters; thus, doubling the diameter of a pipe increases its capacity four times.

_To find the diameter of a pump cylinder_ to move a given quant.i.ty of water per minute (100 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 horse-power necessary to elevate water_ to a given height, multiply the weight of the water elevated per minute in pounds by the height in feet, and divide the product by 33,000 (an allowance should be added for water friction, and a further allowance for loss in steam cylinder, say from 20 to 30 per cent).

_To compute the capacity of pumping engines_, multiply the area of water piston, in inches, by the distance it travels, in inches, in a given time. Deduct 3 per cent for slip and rod displacement. The product divided by 231 gives the number of gallons in time named.

_To find the velocity in feet per minute_ necessary to discharge a given volume of water in a given time, multiply the number of cubic feet of water by 144 and divide the product by the area of the pipe in inches.

_To find the area of a required pipe_, the volume and velocity of water being given, multiply the number of cubic feet of water by 144 and divide the product by the velocity in feet per minute. The area being found, the diameter can be learned by using any table giving the "area of circles" and finding the nearest area, opposite to which will be found the diameter to correspond.