EPAULMENTS.
Batteries at sieges are generally secured on one flank at least, by a parapet called an epaulment, forming an obtuse angle with that of the battery. Their use is to secure the reverse of the terreplein from any flanking fire, and they are not in general made so thick as the parapet, being seldom subject to a direct fire.
ELEVATED SAND-BAG BATTERIES.
The base of the interior slope of a battery reveted with sand-bags is rather broader than that of one reveted with fascines, being about one-third the height of the parapet. Bushel sand-bags are now the only kind in use, and when filled are of the following dimensions:
| Length 20 inches, breadth 10 inches, depth 5 inches. | |
| Number required per gun,—for the interior revetment | 262 |
| Ditto Ditto for the cheeks | 360 |
| Total | 622 |
Sand-bags are laid header, and stretcher, as in masonry; the ends which are tied being always hid. As the sand-bags near the neck of the embrazure would be destroyed after a few hours’ firing, and constantly require repairing, gabions, or casks should be substituted for them.
Howitzer batteries are similar to those for guns, except that the interior openings of the embrazures are 2 feet 6 inches, and the soles are raised, towards the front, about 10°, in order to cover the gunners as much as possible.
Mortar batteries are constructed with the same dimensions as gun batteries (the parapet being generally 8 feet high, and from 18 to 22 feet thick), but, as they have not embrazures, the ditch of elevated batteries is made two feet deeper to obtain the requisite quantity of earth. A preference would in general be given to the sunken, or half-sunken profile for a mortar battery, on account of its requiring less time for its construction, and it being of no consequence whether the platforms are sunken, or otherwise. Mortars are placed at the distance of 15 feet from centre to centre of each other, where no traverses intervene; and the parapet has the same profile as a gun, or howitzer battery.
| When fired at | 45° | they are placed | 12 | feet from the revetment. |
| Ditto | 30° | ditto | 13 | ditto |
| Ditto | 20° | ditto | 21 | ditto |
| Ditto | 15° | ditto | 30 | ditto |
| Ditto | 10° | ditto | 40 | ditto |
HALF-SUNKEN BATTERIES.