The _Merrimac_--she came to England under that name, and not as the _Virginia_, as sometimes stated--was 300 feet over all, and 250 feet on the keel, and 260 feet on the load water-line, and was 51 feet 4 inches beam, and drew 28 feet of water. She was of 3,987 tons measurement, and 4,500 tons displacement. Her engines were of 600 h.p. and presented several peculiarities. The cylinders were of 72 inches diameter, with a stroke of three feet, and there were two rods to each piston. Her screw propeller was on Griffith’s system, and had means of varying the pitch. Normally the screw had a pitch of 26 feet 2 inches; its diameter was 17 feet 4 inches. She had four of Martin’s vertical tubular boilers. The frame of the ship was of live oak, crossed internally with two sets of diagonal iron plates, inclined in opposite directions, and similar plates on the outside strengthened her bow and stern. Her model, or shape, is said to have been of considerable beauty, while her internal arrangements for the comfort and accommodation of the officers and crew were of a high order. She could spread 56,629 feet of canvas, and nautical men here were of opinion that she could easily have borne heavier masts and spars and so have spread more canvas still. However, the weight of her armament had to be considered, and this may have been one reason why she was not more heavily equipped aloft. She was pierced for sixty guns, but on account of the weight and size and effectiveness of those she had, the number on board was only forty. Nevertheless, she was claimed to be, and with good reason, as powerful as anything Europe could show. Two large pivot guns, of 10 inches calibre, and each weighing nearly 5½ tons, were on the upper deck, together with fourteen 8-inch guns, weighing more than three tons each; while on the gun-deck were twenty-four 9-inch guns, each weighing close upon 4½ tons. All these guns were strong enough to fire solid shot, but they were intended to take hollow shot or shell, a custom to which the Americans attached considerable importance. The guns were built on the Dahlgren system, which gave them throughout their length a thickness proportionate to the pressure caused by the explosion of an ordinary service charge of powder. The adaptation of these guns to the Paixhan system of shell-firing was another novelty she presented. As solid shot were more destructive against fortifications and heavy works than the shells or hollow shot--uncharged shells that is--the naval experts of Europe did not look favourably upon explosive shells, preferring to consider them more suitable for large swivel guns, such as were sometimes mounted on the sponsons of paddle boats. The _Merrimac_ had not a solid shot on board. Her guns were of unusual thickness at the breech and thinner than the European guns in that part called the chase, which lies between the trunnions and the muzzle. Their mounting, also, presented some peculiarities. There was no hinder truck, the