NOTE.—Where the target is shown pentrates but no range given it includes all distances up to 2000 yards.] [Illustration: DIAGRAM SHOWING THE PERFORATING POWERS OF PROJECTILES FIRED AT VARIOUS RANGES FROM GERMAN AND FRENCH BREECH-LOADING RIFLED GUNS.] [Illustration: NOTE.—The upper scale is for guns ³/₁₄ of an inch to 1 foot. The lower scale is for targets ¼ of an inch to 1 foot.] [Illustration: SHOWING THE PENETRATING ENERGY, IN FOOT-TONS PER INCH OF SHOTS CIRCUMFERENCE, OF FOREIGN ORDNANCE. AT RANGES FROM 70 YARDS FROM THE MUZZLE OF THE GUN TO 2000 YARDS.] PART III. TORPEDOES. The torpedoes used by and against the different navies of the world may be classed under two general heads, viz., offensive and defensive. Offensive torpedoes may be classified in accordance with the manner in which they are used, as Locomotive, Towing, Spar, and Drifting. LOCOMOTIVE TORPEDOES. _The Whitehead Torpedo._ The Whitehead torpedo consists of a projectile, or more properly speaking a boat, containing a heavy explosive charge, an engine driven by compressed air, screw propellers, and mechanism for regulating the speed, depth of flotation, distance of run, and security of firing arrangements. The general exterior appearance of the torpedo is that of a spindle of revolution, its greatest diameter being in the middle and the lines being so curved as to present a surface of minimum resistance to the water. The dimensions of the torpedo range from fourteen feet in length by sixteen inches in diameter to nineteen feet by seventeen inches. The speed ranges from seven knots for a distance of eight hundred yards up to twenty-five and a quarter knots for two hundred yards, the most powerful combination being fifteen and a half knots for one thousand yards. [Illustration: Whitehead Torpedo and Firing-Tube.] This torpedo, if adjusted to run at any desired depth of water of from five to fifteen feet, and if it be projected from either above water, at the water-line, or below the surface, will rapidly attain the desired depth and maintain it throughout the run. If fired in still water, it will make a straight run in the line of projection, allowance being made for the sweep of currents. It can be adjusted to stop after having run any distance up to its extreme range, and after stopping, it will sink, float, or explode as desired.