Page:Victory at Sea - William Sowden Sims and Burton J. Hendrick.djvu/202

184 their training at New London had been considerably improved. Their procedure represented something entirely new in naval warfare. Since the chasers had to depend for the detection of the foe upon an agency so uncertain as the human ear, it was thought to be necessary, as a safeguard against error, and also to increase the chances of successful attack, that they should hunt in groups of at least three. The fight against the submarine, under this new system, was divided into three parts—the search, the pursuit, and the attack. The first chapter included those weary hours which the little group spent drifting on the ocean, the lookout in the crow's nest scanning the surface for the possible glimpse of a periscope, while the trained listeners on deck, with strange little instruments which somewhat resembled telephone receivers glued to their ears, were kept constantly at tension for any noise which might manifest itself under water. It was impossible to use these listening devices while the boats were under way, for the sound of their own propellers and machinery would drown out any other disturbances. The three little vessels therefore drifted abreast—at a distance of a mile or two apart—their propellers hardly moving, and the decks as silent as the grave; they formed a new kind of fishing expedition, the officers and crews constantly held taut by the expectation of a "bite." And frequently their experience was that of the proverbial "fisherman's luck." Hours passed sometimes without even the encouragement of a "nibble"; then, suddenly, one of the listeners would hear something which his experienced ear had learned to identify as the propellers and motors of a submarine. The great advantage possessed by the American tubes, as already said, was that they gave not only the sound, but its direction. The listener would inform his commanding officer that he had picked up a submarine. "Very faint," he would perhaps report, "direction 97"—the latter being the angle which it made with the north and south line. Another appliance which now rendered great service was the wireless telephone. The commanding officer at once began talking with the other two boats, asking if they had picked up the noise. Unless all three vessels had heard the disturbance, nothing was done ; but if all identified it nearly simultaneously, this unanimity was taken as evidence that something was really moving in the water.