Such guns are built up of a tube or “core” of steel of the required size, upon which is shrunk a jacket, covering the rear, or breech half of the core, outside of which are shrunk on several broad hoops. The cutting out of the bore to exactly the proper caliber and the plowing of the spiral riflings put the gun in readiness for its breech-closing and other attachments. This process requires several months, involves large capital and powerful machinery, and good results imply the very highest workmanship.
THE UNITED STATES CRUISER “BROOKLYN” (STERN VIEW).
Such are the guns of modern men-of-war; and a first-class battle-ship carries four twelve- or thirteen-inch rifles (that is, having a bore twelve or thirteen inches in diameter), several eight- or ten-inch rifles, and many smaller guns arranged to be fired with extraordinary speed, and hence called “rapid-fire” guns; while her upper works and “military tops” fairly bristle with fierce little six-, four-, and one-pounders,—revolving magazine rifles, capable of discharging rifle-balls as fast as a man can turn the crank.
ON BOARD A BATTLE-SHIP GOING INTO ACTION. WORKING THE RAPID-FIRE GUNS.
To give some idea of the size and power of one of the 13-inch guns, whose long muzzles, in pairs, project so far out of the turrets that hide their mountings and firing-crew, let me tell you that it is 40 feet long, more than 4 feet in diameter, and weighs 60½ tons. “It requires 550 pounds of powder to load it, and the projectile weighs half a ton. The muzzle-velocity of the projectile is 2100 feet per second, with the stated charge, and its energy is sufficient to send it through 26 inches of steel at a distance of 600 yards. At an elevation of 40 degrees the range of the gun will be not far from 15 miles.”
In such a ship, deep down within the fortress is the massive and complicated machinery, steam and electric, upon which the life and activity of the whole structure depend. The power is generated in four enormous boilers, seventeen feet in diameter and twenty in length, their steel shells one and a half inches thick, built to carry a working-pressure of 160 pounds to the square inch. Each pair of these boilers, placed fore and aft and side by side, is installed in a separate compartment, with fire-rooms at the ends. Every boiler has four furnaces in each end, which give eight to each fire-room, or a total of thirty-two. The two boiler compartments are separated by a water-tight bulkhead, and by a deep, broad coal-bunker. At the sides of the ship are also coal-bunkers, which supplement the heavy armor-belt by the protection of a mass of coal twelve feet in thickness—in itself a not inconsiderable earthwork, which might arrest the fragments of a bursting shell that had succeeded in piercing the armor. No casualty of naval combat can be worse than the penetration of high-pressure boilers by heavy shells. Their complete protection is an imperative condition, quite as important as the protection of the magazines.
Such is a modern battle-ship—a “wonderful and complex instrument of warfare,” as Lieutenant Staunton has expressed it.
She is filled [he tells us] with powerful agencies, all obedient to the control of man—the creatures of his brain and the servants of his will. Steam in its simple application drives her main engines and many auxiliaries. Steam transformed into hydraulic power moves her steering-gear and turns her turrets. Steam converted into electrical energy produces her incandescent and search-lights, works small motors in remote places, and fires her guns when desired. Every application of energy, every device of mechanism, finds its office somewhere in that vast hull, and the source of all the varied forms of power lies in the great boilers, far down below danger of shot and shell, under which grimy stokers are always shoveling coal. Decades of thought and study, experiment and failure, trial again with partial success, and repeated trials with complete success, have assigned to each agency its appropriate function, and perfected the mechanism through which its work is performed.