Of torpedoes on board there were eight "large" and eight "small," as they called them, which when discharged liberate their own propeller and shoot along at some ten feet below the surface at a rate of up to forty knots an hour, occasionally "breaking surface," i.e., coming up higher and throwing jets of spray in their course and then submerging again. It appears that 55 per cent, or more than half, of the torpedoes fired miss their mark, and with this average they seem satisfied. Once they let go at a ship two torpedoes at 3,000 yards' range, and both missed, the range being too long; but they did not care to come any nearer, as they believed the ship to be well armed. They prefer to fire at 500 to 700 yards, which means that at this range the track or "wake" of a projectile would be discernible for, say, twenty-five to thirty seconds--not much time, indeed, for any ship to get out of the way. At 100 yards' range or less they do not care to fire unless compelled to, as the torpedo is nearly always discharged when the submarine is lying ahead of the object, i.e., to hit the ship coming up to it; it follows that a gun forward is more useful than one aft, the gun aft being of real service when a submarine starts shelling, which she will do for choice from aft the ship rather than from forward of her, where she would be in danger of being run over and rammed. Owing to the big expense of wasted torpedoes it had been planned to build special larger U-boats, two-deckers carrying larger guns for shelling purposes--hence the sooner all merchantmen are well armed the better for them. Talking one day of the number of submarines lost, the officers declared that the Allies' reports of their captures and sinkings were much exaggerated. Naturally they would say so, but the truth is probably best known at headquarters, where such figures are checked up. Once or twice when on the surface we were fired at at long range and quickly submerged, although the U crews recognize they are a difficult target to aim at, let alone hit, as I, too, knew from experience. The periscope is about seven inches in diameter and moves up and down like a piston rod in a cylinder, accompanied by a buzzing kind of sound, which became familiar after a day or two. If required it can reach seventeen feet above the surface and may be used as a flagpost for signals. At its summit is a mirror, three to four inches in diameter, from which images are reflected to a larger mirror below used by the observer. When a ship is first sighted the chief point is to determine her course, which may be easy if she is going in the same direction, but more difficult if not. The next point is to determine as near as possible the speed of the object ship, the size and general lines being considered, and deductions drawn. Next, the distance away of the approaching ship has to be noted.