NOTE.—35 cubic feet of sea water is accounted to be a ton, as in sea
water ballast for steamers, and in calculating displacement of ships.
_Example._ What is the average weight of a cubic foot of Bituminous
coal?
1·256 sp. gravity.
62·5 lbs.
-----
6280
2512
7536
-------
Answer, 78·5000 lbs.
This 78·5 lbs. is the weight of a cubic foot in a _solid block_, but
loose, as used for fuel, a cubic foot weighs about 49.7 lbs. which is
the average of 13 kinds.
_Example._ What is the weight of a solid cast cylinder of copper, 4
inches diameter and 6 inches high?
8·607 sp. gravity.
62·5 lbs.
-----
43035
17214
51642
--------
537·9375 lbs. per cub. ft.
--------
Say 538 lbs.
·7854
16 diam. squared.
-----
47124
7854
-----
12·5664 area of base.
6 high
-------
75·3984 cu. in. in volume
-------
Say 75·4 cubic inches.
cub. in. cub. in. lbs.
Then, as 1728 : 75·4 :: 538 : Answer.
538
----
6032
2262
3770
------
{ 12)40565·2
{---------
1728 { 12)3380·433
{---------
{ 12) 281·702
-------
23·475 lbs.
Answer, 23-1/2 lbs. nearly.