The last cables were being attached to the engine as we stood beside it; for Nordenholt had insisted on a test being made as soon as the machine was completed. The workmen screwed up the connections, everyone stood back a little, and then a switch was pushed home. Immediately the whole misshapen bulk seemed to be galvanised into violent activity and with a roar beyond the roof above us the torrent of escaping helium and argon made its way through the exhaust-pipe. The needle of the indicator dial jumped suddenly upward till it registered many thousands of horse-power. But we had seen all this before and had seen it, too, followed by a collapse; so that we waited eagerly to learn how the engine would stand the strain. For an hour we waited there, while the mechanics poured oil continually into the tanks to keep the racing bearings from heating; and still the machine ran smoothly and the thunder of the escape-pipe roared above us. It was impossible to make oneself heard amid that clangour; and we exchanged congratulations scribbled on odd pieces of paper. After an hour, Milne shut off the disintegrator; and the great engine slowly sank to rest. All of us were still deafened by the sound of the exhaust; and it was by dumb-show and a handshake that Nordenholt conveyed his thanks to the two designers. I heard a faint cheer from the workmen. Nordenholt did not stay long. Within a few minutes, he and I were back in the motor, on the way home. As we went, I heard behind us the tremendous blast of the escaping gases; they had restarted the engine; and to my ears it sounded sweeter than any symphony, for it meant safety to us all. * * * * * When we reached the University, I noticed that Nordenholt stepped from the car with the air of an invalid. He seemed to have used up all his forces in a last effort; and now he moved slowly and almost with difficulty. At the Randolph Stair, he took my arm and leaned heavily on me as we climbed a step at a time. When we reached the top, he seemed out of breath. At last we reached his office and he dropped into his chair at the desk with visible relief. “It’s my heart, Jack,” he said, after a moment or two. “It’s been going wrong for months; and I think it’s badly strained. I knew it was going; and in ordinary circumstances I would have looked after myself; but it wasn’t worth while, as things were. I simply couldn’t take things easy. I had to work on until I saw daylight before me or dropped on the way.” He paused, as though pulling his strength together. In the next room I could hear Elsa’s typewriter clicking. Nordenholt heard it also; and rose after a few minutes. He went to the door between the two rooms and spoke to her, telling her the news of the engine. “It’s success at last, Elsa. We’re through. Everything’s safe now.” I heard her voice in reply; and then he closed the door and reseated himself at the desk.