to purposes of protection, a style of construction now universally adopted and known as cellular was developed by Sir E. J. Reed, then chief constructor of the British Navy, in which the maximum of strength with the minimum of weight was sought after and very fairly obtained. Then began, what has continued to this day, the race between armor and armament; the makers of armor striving to make plates that would effectually resist the largest guns, and the gun-makers using every means at their command to produce guns capable of breaking up or penetrating the heaviest armor. The outcome is, on the side of armor, the solid steel plate with a face case-hardened by the Harvey process-a face so hard that no drill will in the slightest degree affect it, and this extreme hardness gradually shaded off to a soft back to prevent through cracks. On the other hand is the steel built-up breech-loading gun, with a length of from thirty-five to forty-five times its diameter of bore, using slow-burning powder, having low initial pressures and giving a muzzle velocity from two thousand to twenty-five hundred feet per second, and special steel armor-piercing projectiles for the purpose of racking or breaking up the armor and then piercing the hull. This competition has indirectly opened up a new material of some twenty per centum greater strength when compared with wrought iron, known as mild steel, FIG. 2.-IOWA. Section through Armor. which naval architects are em ploying to enable them to produce lighter structures, and to use the weight saved in giving greater thickness to the armor, increased armament, or added power and speed, as the necessities of the design contemplated may demand. Shortly after the introduction of this material, or in 1882, the Congress of the United States appropriated for the construction of three cruisers and one dispatch boat, which are now familiar to us all under the names of the Chicago, Boston, Atlanta, and Dolphin; fortunately for our Government, its corps of naval constructors and engineers had by repeated visits to the ship-yards and gun factories abroad, and a close study of the principles involved in the new methods of construction, kept themselves fully abreast of the progress being made in shipbuilding, marine engineering, and naval artillery, and were thus enabled when the opportunity was given by Congress to promptly take up the work of rehabilitating the navy, and carry it forward successfully. Congress in its appropriation had stipulated that the new vessels were to be constructed of steel; this meant a considerable outlay in capital to the metal producers of the country, who, with the exception of some firms making a specialty of tool steel, had been engaged mainly in the manufacture of wrought iron. However, having full confidence in the determination of Congress to give the country a new navy, they did not hesitate to at once install plants capable of manufacturing steel suitable for shipbuilding these industries, built up within a decade under the stimulus. given by the rebuilding of the navy, to-day challenge the world to produce better material. So rapid has been the progress of our manufacturers, and so fully have all demands upon them been met, that one of our shipbuilding firms is now constructing two mammoth steamers for the Inman International Line, whose ves sels have, since its organization, been constructed on the other side of the Atlantic. The types of war vessels considered by naval authorities to be best suited to the needs of our service may be classed in general terms as battle-ships, armored cruisers, protected cruisers, harbor-defense monitors, gunboats, torpedo-boats (surface and submarine), and rams. The uses and functions of each type differ greatly; some of the more prominent may be broadly stated here. Taking first the battle-ships, we find them to be, of all the types of war vessels, the most powerful in the feature of offense and defense; they are intended to stand and fight, to give and take blows like giants in a prize ring; and the reason can be plainly seen when FIG. 4.-IOWA. Section through Coffer Dams, etc. we appreciate the fact that an enemy can bring his battle-ship within twelve miles of our large seaboard cities, and there taking up a position of vantage, secure from any attack by land, shell the city; the only vessel, then, that can dispute possession with him point by point is a ship of similar powers of doing battle, however successful an attack by torpedo-boat, either surface or submarine, may be when the conditions are suitable. The points, therefore, to be emphasized in the design are protection and armament, or the power to deliver heavy blows with the ability to withstand those of its antagonist; with these must be combined power to enable it to act on the offensive, such as speed, endurance, habitability, and form of hull that will insure seaworthiness. As a purely harbor-defense vessel the monitor stands pre-eminent, the entire hull and battery being protected by armor, and at the same time offering such a small target that it is extremely difficult to hit; but its military value is very seriously impaired when in a seaway, by the short distance of the guns above the water, it being impossible to use them in a heavy sea. Perhaps the vessels most useful for all-around work are the armored cruisers, as they are intended to have great speed, great endurance, guns capable of coping with vessels inferior only to battle-ships, with a very considerable amount of protection afforded to the hull and |