The great hull of a modern battle-ship, as described by Lieutenant S. A. Staunton, U. S. N., which supports and carries the vast weights of machinery, guns, and armor, aggregating perhaps more than ten thousand tons, is built of plates of rolled steel, varying from 1⅜ inches thick at the keel to ¾ inch at the water-line. These are closely jointed and fitted, and bound together with straps, angle-irons, and brackets, so as to make a strong unyielding structure braced in all directions. Then, through the central part of the ship, at least, vertical plates are erected upon the frame and outside plating, which bear a second or inner bottom, thus forming the “double bottom” as high as the water-line, having the space between the inner and outer sheathing separated into a multitude of small water-tight cells, so that an injury to the outside hull would not cause the vessel to leak unless the inner bottom were also punctured. Throughout the whole length of the vessel, reaching from side to side and from the keel to the main deck, are many steel bulkheads, sufficiently strong to resist the pressure of the water, and communicating only by water-tight doors, so that even were an accident, such as a collision or running upon a rock, or an enemy’s shell, to open a hole through both bottoms, the ship would still float, because the inflowing water would be confined to a single compartment, leaving the rest of the ship dry and buoyant. Nothing less than the blow of a ram, smashing through everything and throwing several compartments into one, would be likely to sink such a ship, and this is one reason why ramming has again become prominent in naval tactics. [Illustration: THE FIRST SEA-FIGHT OF MODERN WAR-SHIPS. The Peruvian turret-ship “Huascar” between the fire of the Chilean ironclads “Almirante Cochrane” and “Blanco Encalada,” October 8, 1879.] But while safety from sinking is thus reasonably assured, this is more a precaution of seaworthiness against the accidents of storms than toward injuries receivable in battle. Passenger and freight steamers now have the double bottoms and water-tight compartments, and the best of these have arrangements for mounting light but powerful guns upon their decks, so that they may be utilized by the government in a war emergency as light cruisers, as armed transports, as swift scouts, or in other highly important ways; they will then be coated with a light protective armor, but will not be expected to engage in a contest with a real fighting-vessel.