Fradin leaped--but not at Marvak. He leaped at me. The next instant he was grabbing me, shoving me across the room. And all the tortures of hell were breaking loose around that generator. * * * * * There was a blasting, howling roar of wind. It was the coldest wind ever. It was, I suspect, the cold of absolute zero that struck through that laboratory. Out of nowhere, around that transmitter, a hole seemed to appear. It seemed to be torn in space. It was black, with a curiously liquid kind of blackness. It appeared around the transmitter, and Marvak was at the transmitter. The spy seemed to freeze. A look of amazed fright appeared on his face. [Illustration] Then he seemed to fall. The transmitter seemed to fall with him. Marvak tried to leap, but the footing seemed to fall away under him. He fell out of sight. For a mad instant, while Fradin kicked and hauled me away from that transmitter, the laboratory was hideous with the blast of thunder. Then another murderous crash came, and.... Then there was silence. Utter silence. The only sound was Fradin fighting for his breath. I looked across the room. The transmitter was gone. It just wasn't there any more. Under it, in the floor of the room was a neat, round hole. All the mass of wires that had led into it were neatly severed. Wires came from the transformer to where the hole began, then stopped. Marvak wasn't there. Marvak was gone. Suddenly I turned to Fradin. "You--" I gulped. "You were afraid this would happen. My God, man, what was it?" "It was," he answered, "a hole in the fourth dimension." Then I got it. He had been trying to tell that convention of radio engineers that radio waves were transmitted through the fourth dimension, not through the "ether." He had been able to prove his point but he had refused because he knew that this would happen. "But even if radio waves do pass through the fourth dimension, nothing like this has ever happened," I stammered. "Ordinary broadcasting stations do not put enough power through their transmitters to open this hole," he explained. "It takes power to do it, lots of power. I had calculated how much power it would take. There was a red mark on the input meter of the transmitter. That red line marked the critical point. If more power was put through the transmitter, it would break down the fabric of space between this dimension and the fourth dimension. I knew it would happen. That's why I refused to make a demonstration for the benefit of my skeptical compatriots. If I told them what I had discovered, proved I had discovered it, some fool would be sure to try it, with disastrous results." "But that cold wind," I protested. "This particular region opens out into what must be interplanetary space in the fourth dimension. That cold wind was simply the cold of outer space rushing through what was in effect a window." So that was it. There was a hole in space. And space is cold. "Marvak!" I said weakly.