their low sides allowed almost every other wave to wash over their decks. The turrets of the _Devastation_ and _Thunderer_ were worked on Captain Coles’s system of rollers fixed at the circumference of the base of the turret and centring at the central cylindrical spindle, but their base rested upon the upper deck within the breastwork. In measurements these vessels were considerably smaller than the _Warrior_ or _Minotaur_ classes. The _Warrior’s_ 4½-inch hammered plates would have offered little more resistance than so much glass to the heavy blows which the _Devastation’s_ guns could inflict, nor would the _Minotaur’s_ rolled plates have had much more defensive effect. Even when the _Devastation_ was built, it was contended that the _Hercules_ armour was practically impenetrable to the heaviest of British guns afloat yet, and that of the _Devastation_ was three inches thicker still. One reason why this vessel was so strongly constructed was that she was built on an improvement of the bracketed frame system first introduced by the Admiralty in the _Bellerophon_. These improvements enabled a lighter framework to be constructed without reducing the strength, and the weight thus saved was put into the defensive armour. The _Devastation’s_ upper deck when the ship was in sea-going order was about 4½ feet above water, except at the bows, where a sunk forecastle raised the height to 9 feet, and increased her capacities for going head to sea. The turret ports were 13 feet above the water, so that the guns were carried higher than those of any broadside-armed ironclad afloat. Those of the _Hercules_, for instance, were 11 feet above the water. As at first designed, the _Devastation_ would have had a less freeboard than the _Captain_, but after that disaster the plans of the _Devastation_ were altered considerably, and the Admiralty committee decided that it would be safer and wiser to increase the freeboard amidships. This was done with iron plates raised to a level with the walls of the armoured breastwork, the freeboard for about half the ship’s length being as much as 12 feet.