or beat into leaves S

21,041. 12.176

22,069

12.763

All metals become more dense or heavy by hammering.

9. Since a cubic foot of water, at the temperature of 40° Fahrenheit, weighs 1000 ounces avoirdupois, or 624 lbs., the numbers in the preceding tables under the head Spec. Grav. exhibit very nearly the respective weights in avoirdupois ounces of a cubic foot of the several substances.

We have also given, in another column, the weight in ounces of a cubic inch of each of the several metals: and, with regard to different kinds of wood and stone, the weight in avoirdupois pounds of a cubic foot of each. These, of course, are medium specific gravities and weights; for there are variations, sometimes indeed considerable ones, between the specific gravities of different specimens of the same kind of substance.

These additional columns will evidently facilitate the labour of finding the magnitude of a body from its weight, or the weight of a body from its magnitude. In this respect, too, the following particulars will often be of utility.

10. (1) 430-25 cubic inches of cast iron weigh 1 cwt.

397.60

368.88

352.41

272.8

bar iron

cast brass

cast copper
cast lead

(2) 14.835 cubic feet of paving stone weigh a ton

14.222

common stone

TE

13.505

13.070

12.874

11.273

64.460

64.000

51.650

51.494

granite

marble
chalk
limestone

elm

Honduras mahogany

Mar Forest fir

beech

36.205.

English oak.

11. Prob. To find the internal diameter of a uniform capillary or other small tube.

Let the tube be weighed when empty, and again when filled with mercury, and let w be the difference of those weights in troy grains, and I the length of the tube in inches. Then the diameter required, d=019252

Τ

Thus, if the difference of weights were 500 grains, and the length of the tube were 20 inches: we should have d= = ='019252 × 5='09626 of an inch.*

019252

500

20

12. Prob. To find the weight of a leaden pipe.

If I be the length in feet, d the interior diameter, and t the thickness both in inches and parts of an inch, w the weight in hundred weights: then w=1382 lt (d+t).

For a cast iron pipe, the theorem is

w=0876 lt (d+t);

or nearly of the former expression.

Ex. Let the internal diameter of a leaden pipe be 4 inches, the thickness of an inch; required the weight of 12 feet in

length.

Here ⚫1382 x 12 × 4×44=·1382 × 123=1.762 cwts.

13. Prob. To find the weight of the ring or rim of a cast iron fly-wheel.

Supposing this ring or annulus to be similar to a portion of a pipe of large diameter, the expression for the weight will be similar to the above; but it may be advantageous to change the notation. Let then D be the interior diameter of the fly in inches, d half the difference of the exterior and interior diameters, T the thickness from side to side of the fly, and wits weight in hundred weights: then w=0073 r d (D+d).

The same thing may easily be accomplished thus:-Let a cone of box wood, or of brass, be very accurately turned, of about 6 inches in length, and the diameter of its base about a quarter of an inch; and let its curve surface be very accurately marked with a series of parallel rings, about a twentieth of an inch asunder, from its vertex to its base. Insert this cone carefully in the cylinder (so that their axes shall coincide) as in the diagram: then it will be as v A: Va: A B: ab; where, as the ratio of v A to va is known by means of the equidistant rings on the surface, and ▲ B is known, a b becomes determined.

c

B