The _Devastation_ was probably the first ship in which a built-up keel of steel was introduced. The plates of steel were ⅝-inch in thickness, and the depth of the keel was 4 feet 6 inches, and it was strengthened by an angle-iron 1 inch thick. The stem was a solid forging, the upper deck part being 9 inches thick, and the lower part which formed the ram was 36 inches thick. This immense prow was strengthened by longitudinal iron frames. The stern-post was also forged solid, and was 26 feet in length and weighed 15 tons, and measured 12 inches deep by 8 inches thick. Steel plates riveted vertically over the transverse frames and running longitudinally and crossed by vertical fixed iron plating formed the double bottom. The interior of the hull was divided both longitudinally and transversely into a great number of watertight compartments. The two magazines, one near each end of the ship, were protected from a dropping fire by a bulkhead covered with 5-inch armour plating, and above the magazines again was a strongly constructed deck 4 feet 6 inches below the load water-line. The armoured belt was 9 feet 6 inches broad amidships, but tapered off gradually towards the ends. The armour-plating was 18 inches thick amidships, and gradually reduced to 9 inches towards the extremities. The breastworks or armoured walls built up from the upper deck near the forecastle, and extending to a wall behind the after turret, were 7 feet high, 74 feet long, and had an interior breadth of 50 feet. Their armour-plating varied from 10 to 12 inches, with the usual backing of wood and iron frames, and an inner iron skin. The deck was 2 inches of iron covered with 4 inches of oak. The turrets, which stood at either end of the breastwork, were 31 feet 3 inches in exterior diameter, and 24 feet 1 inch interior diameter; they were built up as follows: Outside, 9 inches of iron plating, then 9 inches of Italian oak set in iron frames, then 6 inches of iron plating, then 6 inches of Italian oak set in iron frames, then two thicknesses of iron plating each ¾-inch thick, to form the inner skin, then iron frames 10 inches in depth, and finally a series of rope mantlets, or nets, to protect the men working the guns from injury through fragments of rivets or bolts being driven in by a shot striking the outside of the turret in battle.