"Well, it's a tiny affair no larger than a pea, and will so magnify sound in connection with an electric current and a telephone receiver, such as I have here, that the footsteps of a fly on a sheet of paper sound about like the tramping of an army. It's so powerful," he continued, "that if I were to place it in the end of a tube and point the tube, say, toward that island out there, any noise going on---a wagon rattling along the road or a child naming--I should be able to hear on this side, provided I had arranged the microphone so as to shut out all intervening noises. For instance, this microphone here is sensitive to no sound but that of the bell and the vibrations that I hope may be reflected back from the sea bottom. But we'll soon know whether it will work," he cried. "Row about twenty rods farther and then I'll tell you not only the depth of the water at that point, but the character of the bottom and whether it will be safe for our big liner to advance." He was trembling all over and Rachel reflected his interest. She sent the boat forward a few strokes, then rested on the dripping oars. Nature, it seemed, was in her most approachable mood and at a hint of coaxing would reveal her secrets; yet the girl was conscious of something in the phenomena of the sea implacable and resistant to the efforts of man. Concealed promontories, hidden shoals, submerged headlands, treacherous peaks, drowned under the ceaseless rushing of waters--would the Voice come back bearing tale of all this?--or, if mud, weeds, fish, incrustations of shell--would the Voice proclaim safety, and the inventor know the very thickness of that rolling, beauteous mantle of mystery? Nothing of the poetic significance of the test was lost on the girl, and she felt the hand of pity at her throat when she witnessed Emil's disappointment manifest all over him like a blight. Then she gloried when she saw him repeat the test. Come what might, it was clear he had faith in himself. Tenaciously he passed from one test to another. He contorted himself, stooping in the bottom of the boat, his eyes bright with the steady flame of his determination. He took off his coat and, flinging back his hair, listened with the receiver at one ear while he covered the other with his free hand. At last he was able to hear: first, the muffled stroke of the bell, then the extremely feeble sound vibrations reflected from the sea bottom through the microphone-telephone; and by the period of time which elapsed between the bell stroke and the return impulse, he was able, after innumerable experiments, to estimate closely the distance which the sound travelled before being sent back.