HOW THE BIG GUNS ARE USED.
The 14-pounder, although not included in the navy armament, is given for the purpose of comparison, since it is with guns of this caliber that some of the Spanish torpedo-boat destroyers are armed. The largest gun as yet mounted on our largest torpedo-boats is the 6-pounder, while a single 1-pounder is the gun armament of the ordinary torpedo-boat. The Hotchkiss revolver cannon is not given in the table because its caliber, etc., is the same as that of the 1-pounder, and, in fact, the latter has superseded it in the latest armaments, so that it is now found only on the older ships of the modern fleet. The machine guns are not given because their effective work is practically the same. The Gatling is of 45-caliber, and uses the government ammunition for the Springfield rifle.
A look over the table shows some general principles in the matter of powder and shell used. The powder charge is about half the weight of the shell, while the length of the shell is a little over three times its diameter.
To attain its extreme range a gun must be given an elevation of about fifteen degrees. The greatest elevation given any of the guns on shipboard is about six degrees. This limit is made by two factors—the size of the portholes or opening in the turrets for the larger guns, and the danger of driving the gun backward and downward through the deck by any greater elevation. The practical range of the great guns of a ship, the ten, twelve, and thirteen-inch, is not, therefore, believed to be over five or six miles, and even at that range the chances of hitting a given object would be very small. A city could, of course, be bombarded with, effect at such a range, since a shell would do tremendous damage wherever it might strike, but a city to which a ship could approach no nearer than say seven miles would be safe from bombardment.
The muzzle velocities given the shells from the guns of the navy are something tremendous, while the muzzle energy is simply appalling. The shell from the thirteen-inch gun leaves the muzzle at a velocity of 2,100 feet a second, and with an energy of 33,627-foot tons, or the power required to lift one ton one foot. From this velocity the range is to 1,800 feet a second in the one-pounder, although from the three-pounder at 2,050 feet it averages about the same as the thirteen-inch. The five-inch rapid-fire gun has the greatest muzzle velocity at 2,250 feet. The muzzle energy is, of course, small in the smaller guns, being only twenty-five-foot tons in the one-pounder and 500 tons in the fourteen-pounder.
The power of penetration has already been given in a general way, but the power of penetration of steel is much greater. At its muzzle velocity the thirteen-inch shell will penetrate 26.66 inches of steel, the twelve-inch, 24.16 inches; the ten-inch, 20 inches, and the five-inch, 9 inches. The one-pound shell bursts in piercing one-fourth and nine-sixteenths-inch plates, scattering its fragments behind the target.
It may be interesting to note that the cost of one discharge of a thirteen-inch gun is $800, and that when a battleship like the Massachusetts lets loose her entire battery, both main and secondary, the cost of a single discharge is $6,000.