_Gun_-BATTERY, is a defence made of earth faced with green sods or fascines, and sometimes made of gabions filled with earth: it consists of a _breast-work parapet_, or _epaulement_, of 18 or 20 feet thick at top, and of 22 or 24 at the foundation; of a ditch 12 feet broad at the bottom, and 18 at the top, and 7 feet deep. They must be 7¹⁄₂ feet high. The embrasures are 2 feet wide within, and 9 without, sloping a little downwards, to depress the metal on occasion. The distance from the centre of one embrasure to that of the other is 18 feet; that is, the guns are placed at 18 feet distance from each other; consequently the _merlons_ (or that part of solid earth between the embrasures) at 16 feet within, and 7 without. The _genouilliers_ (or part of the parapet which covers the carriage of the gun) are generally made 2¹⁄₂ feet high from the platform to the opening of the embrasures; though this height ought to be regulated according to the semi-diameter of the wheels of the carriage, or the calibre of the gun. The platforms are a kind of wooden floors, made to prevent the cannon from sinking into the ground, and to render the working of the guns more easy; and are, strictly speaking, a part of the battery. They are composed of 5 sleepers, or joists of wood, laid lengthways, the whole length of the intended platform; and to keep them firm in their places, stakes must be driven into the ground on each side: these sleepers are then covered with sound thick planks, laid parallel to the parapet; and at the lower end of the platform, next to the parapet, a piece of timber 6 inches square, called a _hurter_, is placed, to prevent the wheels from damaging the parapet. Platforms are generally made 18 feet long, 15 feet broad behind, and 9 before, with a slope of about 9 or 10 inches, to prevent the guns from recoiling too much, and for bringing them more easily forward when loaded. The dimensions of the platforms, sleepers, planks, hurters, and nails, ought to be regulated according to the nature of the pieces that are to be mounted. The powder magazines to serve the batteries ought to be at a convenient distance from the same, as also from each other; the large one, at least 55 feet in the rear of the battery, and the small ones about 25. Sometimes the large magazines are made either to the right or left of the battery, in order to deceive the enemy; they are generally built 5 feet under ground; the sides and roof must be well secured with boards, and covered with earth, clay, or something of a similar substance, to prevent the powder from being fired: they are guarded by centinels. The balls are piled in readiness beside the merlins between the embrasures.