The sights used with naval guns are all of the tangent pattern, and all except the boat-guns are provided with sights on both sides. The socket for the tangent-sight is bored through the breech-piece, the upper part having steel or bronze bushing and a clamp-screw passing through at right angles. The sight is cylindrical, with a flat rear surface on which is marked elevations to sixteenths of degrees. On the left cylindrical side, elevations for every 100 metres are marked for common shell, and on the right for chilled or steel shot. The head of the sight consists of a rectangular cross-head fastened to the top of the bar, in whose upper surface a swallow-tailed groove is cut in which travels the sight-notch. On the face of the cross-head, gradations of sixteenths of a degree corresponding to elevations are marked, and the sight-notch carries a small pointer. The gradations are marked each way so as to account for drift and deviation to the right or left. The forward sight is cylindrical, with a conical point, and screws into the trunnion-hoop. Sights for boat-guns differ in having gradations only on the rear face, and the sliding leaf works by an endless screw. These sights are all vertical. With some boat-guns, however, the tangent-sight is placed at a permanent angle of deflection, in which case there is no sliding leaf. ITALIAN ORDNANCE. A = Calibre. B = Over all. C = Rifled Bore. D = Powder Chamber. -------------------------+------+---------------------- NAME, NATURE, AND | | LENGTH. CLASSIFICATION. | | | +-------+-------+------ | A | B | C | D | | | | -------------------------+------+-------+-------+------ | In. | In. | In. | In. Armstrong pattern Muzzle-loaders. 43 cm. | 17 | 392 | 311.3 | 52 28 ” New Model | 11 | 173 | 120.5 | 24.4 28 ” Old ” | 11 | 173 | 119 | 26 25 ” No. 1 Long | 10.1 | 173.2 | 119.1 | 26 25 ” ” Short | 10.1 | 167.6 | 113.9 | 26 25 ” No. 2 | 10.1 | 156.1 | 111.1 | 14 22 ” | 9 | 156.1 | 105.6 | 19.7 20 ” | 8 | 130 | 88.6 | 15.8 Cast-iron Muzzle-loaders. 16 ” Wrought-iron Tube | 6.5 | 142.1 | 104 | 13.8 16 ” | 6.5 | 126.7 | 94.1 | 13.9 Armstrong Breech-loader. 12 ” | 4.7 | | 70.4 | 19.7 Bronze Breech-loader. 7.5 ” | 2.95| 70.1 | 52.4 | 10.2 Bronze Muzzle-loaders. 8 ” | 3.4 | | 45.3 | 9.8 8 ” | 3.4 | | 31.9 | 3.5 Cast-Iron Muzzle-loader. 12 ” | 4.77| | 73.3 | 6.3