=65.= =Mined Magazine.=--When the soil, by absence of rock and water, admits of mining, greater cover against vertical fire can be obtained with less work by mining out the powder-chamber and passages (Pl. VIII, Figs. 78, 79). The figures illustrate one of minimum dimensions, which is constructed as follows: The entrance 10' × 5' by 5' 6" deep is first excavated, revetted with frames and sheeting and covered with balks and earth as indicated. At 1 foot from the end a shaft 2' × 5' is sunk to a depth of 12'. From the front of this a gallery 2' × 5' 6" is driven for about 6'; at the end of this galleries 5' 6" × 2' are broken out on each side and driven so far as may be necessary to store the requisite number of ammunition-boxes. (For method of sinking shafts, driving galleries, etc., see Military Mining, Arts. 25, 33, and 44-48.) The excavated earth is spread on top of the magazine to increase the thickness of the cover already given by that excavated from the passages. A ring-bolt is placed in the balk directly over the shaft, for attaching a hoisting tackle for removing the earth during construction and for hoisting and lowering ammunition-boxes afterward. A door opening outward may be hung at the entrance, and the passage may be blinded as previously described, if it is thought necessary. The communications are arranged in essentially the same way as for the magazine previously described. The dimensions given are the least which will allow moderately free access and good cover. The magazine should be constructed, by good miners, in two nights and the intervening day, and will store about 4000 pounds of cartridges in boxes. When time and the character of the ground admit, and larger capacity is desired, the shaft may be made wider and deeper, the gallery wider and longer, and the powder-chamber deeper, longer, and wider, if desired. The excavation for the entrance and approaches, the placing of balks, and the levelling and ramming of the earth-cover, should be done by night; the mining work can be carried on both night and day. =66.= =Elevated Magazines.=--When the presence of rock or water in the soil prevents sinking the magazines to the full depth above given, they must be sunk so far as practicable and given the least possible clear height of powder chamber, with the best attainable overhead cover. This should be strengthened by the use of railroad iron or rolled iron beams, when available. The cover against direct fire should be increased up to 30 feet, and the front slope be made gentle, like a glacis. A screen made of an earthen bank with a glacis slope should also be used if possible. These precautions having been taken, the depth of the powder-chamber in the direction of the hostile fire should be reduced to a minimum, and the storage of large quantities of powder be avoided, so far as possible, by constructing a number of small magazines at the most convenient places in the vicinity of the battery.