This multiplied by one-sixth gives the contents in cubic inches—
| 4068 |
| 6 |
| ——— |
| 24408 |
| ===== |
Then if 24408, the contents of a balloon three feet in diameter is divided by 1728, the number of cubic inches in a foot, you have fourteen cubic feet as the capacity of a three feet balloon, thus—
| 1728) | 24408 | (14 cubic feet |
| 1728 | ||
| —— | ||
| 7128 | and | |
| 6912 | ||
| —— | ||
| 216 | inches over. | |
| ==== | ||
If you want to find the internal capacity of a balloon three feet in diameter, first multiply the three feet by three feet to give the circumference (nine feet), which gives twenty-seven, the surface.
Then multiply by 5236 to ascertain the cubic contents.
| 5236 | |
| 27 | |
| ——— | |
| 36652 | |
| 10472 | |
| ———— | |
| 14·1372 | being 14 cubic feet and a fraction. |
| ======= | |
| 14 |
I will just give one more simple calculation of the capacity and superficial surface of a balloon thirty-three—instead of three—feet in diameter.
| 33 | |
| 33 | |
| —— | |
| 99 | |
| 99 | |
| —— | |
| 1089 | circumference. |
| 33 | diameter. |
| ——— | |
| 35937 | surface. |
| ·5236 | decimal numbers. |
| ——— | |
| 215622 | |
| 107811 | |
| 71874 | |
| 179685 | |
| ————— | |
| 18816·6132 | cubic contents. |
| ========= |
Carburetted hydrogen or coal gas, should raise from 402 pounds, as 1,000 feet of light gas should raise 40 pounds to the 1,000 cubic feet.