Dr. Plantet started up the pumps. With my ear near the inner hull I could hear the water circulating. Bubbling, gurgling at first; and then, as its speed increased, humming with a sound almost electrical. And at the windows, which now I knew to be double bull’s-eyes, I could see the water circulating. A thick flat sheet of it flashing past with a queer, oscillating, wavelike swing so swift the eye could scarce remark it. “These pumps operate automatically, Jeff. A faster flow, as our depth increases.” He moved the switch-lever over to another contact; the humming went up to a higher pitch. “Put your hand on the hull, Jeff.” The burnished cold surface was gradually warming. He shut off the pumps. He added: “Curiously enough, Jeff, it gives us heat against the cold of the depths.” He smiled. “Rather too much heat, if we use the pumps for more than an hour. But I have a refrigeration coil to help cool it. I think we shall have no trouble, even when running deep for considerable periods of time.” We were not long on board the Dolphin this morning; there was so much that Dr. Plantet had to do. A center passage like a narrow spider-bridge hung midway of the vessel’s interior. Beneath it, in the center, the Parodyne engine lay in its terrace of burnished blocks, with coils and dials and intensifying tubes glowing dimly yellow in the gloom as Dr. Plantet started it at its lowest operating force. Almost silent--a vague burring sound as the electrons were tossed fluorescent in its storage globe--a green fountain of burring light, running into the outlets, through the pressure valves of the water-jacket, to plunge at last into the sea beneath our stern. Tiny electronic streams--there were six of them--reconverted by the water’s contact from negligible electric mass into ponderable gas of radiolite, striking the ocean and forcing the Dolphin forward as a rocket is thrust upward by the fire-stream from its tail. * * * * * We stood watching the Parodyne for a moment as it worked up its energy from the morsels of pitchblende it was breaking down into freed electrons. An ounce of fuel to run us for a day. So silent, so free-running, one could hardly hear it. A little jewel of a modern engine, so recently developed that there were only three, even of this small size, in existence. We inspected the several tiny rooms which hung in frames to the sides of the passage, with the ballast and water tanks and pressure chambers beneath them. A tiny galley for Polly. Three rooms with bunks; a narrow space, by courtesy called the diner, with folding table and chairs.