A final stage in the evolution of the central-battery ship was attained in the _Alexandra_, laid down in ’72. The type had proved tenacious of life, and, for masted vessels, still held its own up to this point against the turret system. The design for the _Alexandra_ gave as complete an all-round fire as was attainable in a central-battery ironclad; for the first time, it was said, we really had a masted ship with satisfactory all-round fire. Generally like the _Audacious_ class, the _Alexandra_ possessed an advantage in that the two forward guns of the upper deck battery were 25 ton instead of 18 ton, and in having, in addition to the six broadside guns of the main deck battery, two additional 18-ton guns mounted so as to be capable of firing nearly ahead and on the beam as well. Designed to fulfil the requirements of “end-on” fighting, she made a heavy sacrifice of broadside fire to obtain a maximum of bow fire; and at a later date, when a different valuation had come to be placed on axial fire, this sacrifice was noted against her. “She could only take her place at a disadvantage in any form of battle which was suited to the armaments of the ironclads that had gone before her.”[167] Nevertheless she was a formidable vessel. Defensively, too, she was pronounced to be conspicuously successful; her armour belt, which attained a thickness of 12 inches at the water-line amidships, was carried down at the bow to cover and strengthen the stem, and to protect the vessel from a raking fire. For the protection of the stern against a raking fire, an armour bulkhead was worked across the after part, extending to a depth of 6 feet below the water-line. The _Alexandra_ was the last of the purely “central battery” ships.[168] By the time she was launched experience had set the seal of approval on another type, to the evolution of which we must now revert. §