To find how much powder will fill a shell.
Divide the cube of the internal diameter of the shell in inches by 57·3, for the pounds of powder.
To find the size of a shell to contain a given weight of powder.
Multiply the pounds of powder by 3.75, and the cube root of the product will be the diameter in inches.
To find the weight of a Shell. Rule.
Double the difference of diameters of the shell and hollow sphere, and 7 times the result gives the weight in pounds, cutting off the two right hand figures of whole numbers.
Example. Let the diameter of the shell be 13 inches, and that of the hollow sphere 9·5. Then the cube of 13 is 2197, and that of 9·5, is 857·357; the difference is 1339·625, its double is 2679·25, which multiplied by 7, gives 18754·625; and cutting off two places in whole numbers, the result is 187 lb. or 1 cwt. 2 qrs. 21 lb. the weight of the shell.
French Shells, in French weights and measures.
| Kind. | Weight. | Diam- eter. | Powder con- tained in Shells. | Powder for bursting. | Diameter of Fuze Hole. | Thick- ness of Metal. | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Out- side. | In- side. | |||||||||||
| lbs. | Inches. | lbs. | oz. | lbs. | oz. | Lines | Po. | Lines | Po. | Lines. | ||
| 12 | inch | 150 | 12 | 17 | 5 | 15 | 9 | 15 | 16 | |||
| 10 | —— | 100 | 10 | 10 | 3 | 15 | 9 | 15 | 16 | |||
| 8 | —— | 43 | 8 | 4 | 1 | 1 | 12 | 11 | 10 | |||
| 6 | —— | 23 | 6 | 2 | 8 | 12 | 11 | 10 | 6 | 10 | ||
Dimensions of shells for guns and carronades made with an equal thickness of metal.