He nodded to the left. "That's Miguel's coat on the floor. I wasn't sure it would still be here. The atomic key you were searching for so industriously last night is in one of its pockets. Miguel was standing just there, with the coat folded over his arm, when I saw him last--perhaps two or three seconds before I was surprised to discover I was no longer looking at the instrument controls in our laboratory." "Where were you?" Dowland asked. "Six hundred thousand years in the past?" "The instruments showed a fix on that point in time," Trelawney said. "But this was, you understand, a preliminary operation. We intended to make a number of observations. We had not planned a personal transfer for several more weeks. But in case the test turned out to be successful beyond our expectations, I was equipped to make the transfer. That bit of optimistic foresight is why I'm still alive." What was the man waiting for? Dowland asked, "What actually happened?" "A good question, I'd like to know the whole answer myself. What happened in part was that I suddenly found myself in the air, falling toward a river. It was night and cloudy, but there was light enough to show it was a thoroughly inhospitable river.... And now I believe"--his voice slowed thoughtfully--"I believe I understand why my brother was found outside the closed door of this building. Over there, Dowland. What does that look like to you?" Near the far left of the building, beyond the immediate range of the light that streamed from the machine stand, a big packing crate appeared to have been violently--and rather oddly--torn apart. The larger section of the crate lay near the wall, the smaller one approximately twenty feet closer to the machine platform. Assorted items with which it had been packed had spilled out from either section. But the floor between the two points of wreckage was bare and unlittered. Except for that, one might have thought the crate had exploded. * * * * * "It wasn't an explosion," Trelawney agreed when Dowland said as much. He was silent a moment, went on, "In this immediate area, two space-time frames have become very nearly superimposed. There is a constant play of stresses now as the two frames attempt to adjust their dissimilarities. Surrounding our machine we have a spherical concentration of those stresses, and there are moments when space here is literally wrenched apart. If one were caught at such an instant--ah!" To Dowland it seemed that a crack of bright color had showed briefly in the floor of the building, between the door and the machine platform. It flickered, vanished, reappeared at another angle before his ears had fully registered the fact that it was accompanied by a curiously chopped-off roar of sound. Like a play of lightning. But this was....