Though the above principles given for the erection of field works may assist an officer’s recollection who may be employed on that duty, the memorandums given respecting permanent fortification pretend to no such object: but may serve to remind an officer, if he should visit a fortification, of its essential requisites; and may assist his observations in passing round the works.
FUZES.—Composition.
| Saltpetre | 3 lbs. | 4 oz. |
| Sulphur | 1 | — |
| Mealed powder | 2 | 12 |
| Nature. | Fuze Diameter. | Composition. | Drove by one man in 1 day. | ||||
|---|---|---|---|---|---|---|---|
| below the cup. | at the bottom. | at the cup. | Diameter. | Length. | Time it burns. | ||
| Inches. | Inch | Inches. | Inches. | Inch. | Inches. | ″ | Nᵒ. |
| 13 | 2.1 | 1.575 | 2.49 | .5 | 8.4 | 35 | 25 |
| 10 | 1.8 | 1.35 | 2.13 | .438 | 7.2 | 33 | 25 |
| 8 | 1.3 | 1.25 | 1.78 | .375 | 6.37 | 29 | 30 |
| 5½ | 1.1 | .825 | 1.3 | .275 | 4.4 | 18 | 50 |
| 4⅖ | 1.0 | .75 | 1.18 | .25 | 3.5 | 15 | 700 |
| Grenades | 0.8 | .6 | .9 | .2 | 2.25 | 1000 | |
Diameter inside the cup is 3 diameters of the bore.
Depth of the cup 1½ do.
Thickness of wood at bottom of the bore, 2 diameters.
To find the Length of Fuzes for any Range.
The 13 and 10 inch fuzes of the same length burn so nearly equal, that one common length answers both, as do the 8 inch, 5½ and 4⅖. Therefore, to find the length of fuze for any range, multiply the time of flight by .22 for the 13 and 10 inch, and by .24 for the 8, 5½, and 4⅖; which is the decimal part of an inch a fuze burns in a second. Fuzes are thought to keep better by being painted; and for field service, are often marked off by black lines into seconds and ½ seconds.
G abions—Small gabions of 3 feet high, and 2 feet diameter, are made with least trouble, and are easiest carried. The pickets for them must be 1½ or 2 inches thick, and 4 feet long. Large gabions are 6 feet high, and 3 feet in diameter; and require two men to carry them. The smallest gabions or baskets are formed of pickets, 1 inch in thickness, and 1 foot long: they are 12 inches in diameter at top, and 10 at bottom. The small gabions have 7 or 8 pickets, the large ones 9 or 10.