Epaulement— Breadth at bottom 23 feet.
Breadth at top 18
Height within 7
Height without 6 ft. 4 in.
Slope, interior ²⁄₇ of h’gt.
Slope, exterior ¹⁄₂ of h’gt.
Note.—The above breadths at top and bottom are for the worst soil; good earth will not require a base of more than 20 feet wide, which will reduce the breadth at top to 15 feet; an epaulement of these dimensions for two guns will require about 4200 cubic feet of earth, and deducting 300 cubic feet for each embrazure, leaves 3600 required for the epaulement. In confined situations the breadth of the epaulement may be only 12 feet.
Embrazures— Distance between their centers 18 feet
Openings, interior 20 inc.
Openings, exterior 9 feet
Height of the sole above the platform 32 inc.
Note.—Where the epaulement is made of a reduced breadth, the openings of the embrazures are made with the usual breadth within, but the exterior openings proportionably less. The embrazures are sometimes only 12 feet asunder, or even less when the ground is very confined. The superior slope of the epaulement need be very little, where it is not to be defended by small arms. The slope of the side of the embrasures must depend upon the height of the object to be fired at. The Berm is usually made 3 feet wide,[38] and where the soil is loose, this breadth is increased to 4 feet.
2. Howitzer Batteries.—The dimensions of howitzer batteries are the same as those for guns, except that the interior openings of the embrazures are 2 feet 6 inches, and the soles of the embrazures have a slope inwards of about 10 degrees.
3. Mortar Batteries.—Are also made of the same dimensions as gun batteries, but an exact adherence to those dimensions is not so necessary. They have no embrazures. The mortars are commonly placed 15 feet from each other, and about 12 feet from the epaulement.
Note.—Though it has been generally customary to fix mortars at 45°, and to place them at the distance of 12 feet from the epaulement, yet many advantages would often arise from firing them at lower angles, and which may be done by removing them to a greater distance from the epaulement, but where they would be in equal security. If the mortars were placed at the undermentioned distances from the epaulement, they might be fired at the angles corresponding: