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20 common bricks to a cubic foot, when laid;

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Laths are 1 to 1 inches by four feet in length, are usually set of an inch apart, and a bundle contains 100.

Stourbridge fire-brick, 9×4×2 inches.

HAY.

10 cubic yards of meadow hay weigh a ton. When the hay is taken out of large or old stacks, 8 and yards will make a ton. 11 to 12 cubic yards of clover, when dry, weigh a ton.

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DISPLACEMEnt of EngliSH VESSELS OF WAR, WHEN LAUNCHED AND WHEN READY FOR SEA.

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ILLUSTRATION. If 4 inch round iron is worth $135 per ton, then band iron is worth $100 per ton, for 27 is to 20 as 135 to 100.

POWER REQUIRED TO PUNCH IRON AND COPPER PLATES.

Through an Iron Plate, with a Punch Inch in Diameter.

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Through a Copper Plate, with a Punch Inch in Diameter.

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The force necessary to punch holes of different diameters through metals of various thicknesses, is directly as the diameter of the hole and the thickness of the metal.

To ascertain the Force necessary to Punch Iron or Copper

Plates.

RULE.-Multiply, if for iron, 150000, and if for copper, 96000, by the diameter of the punch and the thickness of the plate, each in inches; the product is the pressure in pounds. The use of oil reduces the above 8 per cent.

X2

IRON.

85

CAST IRON expands 162000 of its length for one degree of heat; greatest change in the shade in this climate, of its length; exposed to the sun's rays, 1000; shrinks in cooling from to of its length; is crushed by a force of 93,000 lbs. upon a square inch; will bear, without permanent alteration, 15,300 lbs. upon a square inch, and an extension of 1200 of its length.

Weight of modulus of elasticity for a base of an inch square, 18,400,000 lbs. ; height of modulus of elasticity, 5,750,000 feet.

WROUGHT IRON expands 143000 of its length for one degree of heat; will bear on a square inch, without permanent alteration, 17,800 lbs., and an extension in length of cohesive force is

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diminished by an increase of 1 degree of heat.

Weight of modulus of elasticity for a base of an inch square, 24,920,000 lbs. ; height of modulus of elasticity, 7,550,000 feet. Compared with cast iron, its strength is 1.12 times, its extensibility 0.86 times, and its stiffness 1.3 times.

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EXAMPLE.-What is the weight of a bar of rolled iron 14 inches square and 12 inches long?

In column 1st find 14, and opposite to it is 7.604 pounds, which is 7 lbs. and 604

1000

of a lb. If the lesser denomination of ounces is required, the result is obtained as follows: Multiply the remainder by 16, pointing off the decimals as in multiplication of decimals, and the figures remaining on the left of the point indicate the number of ounces.

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If the weight for less than a foot in length was required, the readiest operation is this:

EXAMPLE.—What is the weight of a bar 64 inches square and 9 inches long? In column 5th, opposite to 64, is 132.040, which is the weight for a foot in length. 64×12 inches =132.040

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The application of this table is precisely similar to that of the preceding one.

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