MAGAZINE. Magazines are of two descriptions, permanent or temporary. Permanent magazines are strong buildings constructed generally of brick or stone within a fortified place, or in the neighbour hood of a military or naval station, in order to contain in security the gunpowder or other warlike stores which may be necessary for the defence of the place, or for the use of the troops who are to perform military duty In the province or district. Temporary magazines are such as are constructed during a siege for the supply of the batteries, or such as are hastily constructed in • fortress for expense magazines.
On account of the liability of gunpowder to become deteriorated by humidity and by variations in the state of the air, the buildings in which it is contained are constructed with every precaution necessary to ensure dryness, and, as nearly as possible, a uniformity of tempera ture within them. They are generally in places remote from other buildings; they are furnished with metallic conductors, in order to avert danger from lightning; and, for security against the attempts of ill-disposed persons, they are surrounded by a wall and ditch. When in situations where they may become the objects of hostile measures, they are made shell-proof.
A magazine within the walls of • fortress is usually formed on en esplanade ; and, if small, it may be in the interior of some bastion remote from the front against which an attack of the enemy is likely to be directed. But it would be preferable that such buildings should be in some work beyond the main rampart of the place, that an accident may be attended with as little detriment as possible.
The powder required for the immediate service of the works on the front attacked is taken from the general magazine, and placed in what are called Capt. Ilde magazines ; that is, In temporary bomb-proof buildings, or in casemate/ formed in the rampart along that front, from whence it is conveyed to the batteries. These casemates or soulersrias should be as well ventilated as possible, by having doors and windows in the interior aide of the rampart, and loop-holes or small perforations on the side next to the main ditch. They sometimes constitute the only bomb proofs belonging to a fortress ; and then they become of the utmost importance, serving as well for the abode of the troops, when not on duty, as for the preservation of the powder and stores. [Bosteeerooe • such situations however, as magazines, they are to some disadvantages from which tweeted buildings are free; for besides the humidity, which the means they possess for ventilation are not sufficient entirely to remove, the blow mg up of any one by an accident would evidently destroy the rampart, and expose the place to the risk of an immediate assault. And when
the vault springs from the back of the wall which constitutes the exterior revetment of the rampart on any face of the work, its lateral pressure would facilitate the formation of a breach by overturning the wall as soon as the latter became weakened by the fire from the enemy's battering artillery.
The dimensions of magazines are necessarily dependent on the quantity of powder which they may be required to contain. Vauban, in hie "eraite eur la Defense des Placcae speaking of such as are made in the ramparts of fortresses, recommends them to be from 8 to 12 feet wide, with semicircular-beadee vaults ; and he proposes that the barrels of powder should be placed in them hi two rows, with a passage from 3 to 4 feet wide along the middle. The great magazines which have been constructed in this country consist of several parallel vaults, separated from each other by brick partition walls, in which are doorways for allbrding lateral communication. Each vault is about 90 feet long and 19 feet wide internally, !red it has a door at each extremity. The side walla are from 8 to 10 feet thick, and are strengthened by buttresses built at intervals against them. The concave or interior enlace of each vault, in a vertical and transverse section, is nearly of a parabolical figure, above the springing crourses; and the exterior surface has the form of two inclined planes meeting In • longitudinal ridge-line above the middle of the vault. The thickness of the brickwork forming the vaulted roof is therefore various • at the crown it is 7 or 8 feet, and on the banes% about 3 feet, this being considered sufficient to resist the shock of falling shells. The vault, on the exterior of the inclined planes, is covered with fiat tiles, slates, or, still better, asphalts ; and the gutter between every two roofs with sheet-lead or copper. The height interiorly, from the level of the floor to the crown of the arch, is 19 feet ; and the lines at which the vaulting springs from the side walls are at beef that distance above the floor. The narrow vertical perforations which are made through the aide and end walls, for the purpose of giving air to the Interior, are cut so as to leave a solid block or traverse of the brick work in the middle of the thickness of the wall ; the line of the per foration branching laterally from its general direction, end passing along the two sides of the traverse. By this construction, while air is admitted, no object capable of doing mischief can be thrown in from the exterior of the building. The flooring-planks are, of course, laid on joists raiser considerably above the ground. One vault, of the dimensions above given, would contain 2500 barrels, or 225,000 lbs. of powder.