Behind him, Kathryn flipped her speedster end for end and led the retreat. She left the tube before--"before" is an extremely loose and inaccurate word in this connection, but it conveys the idea better than any other ordinary term--she got back to Base. She caused an officer to broadcast an "evacuation" warning, then hung poised high above Base, watching intently. She knew that Kinnison could not leave the tube except at its terminus, hence would have to materialize inside Base itself. She had heard of what happened when two dense, hard solids attempted to occupy the same three-dimensional space at the same time; but to view that occurrence was not her purpose in lingering. She did not actually know whether there was anything in the tube or not; but she did know that if there were, and if it or they should follow her father out into normal space, even she would have need of every jet she could muster. Kinnison, maneuvering his Boskonian cruiser to a halt just at the barest perceptible threshold of normal space, in the intermediate zone in which nothing except dureum was solid in either space or pseudospace, had already given a great deal of thought to the problem of disembarkation. The ship was small, as spaceships go, but even so it was a lot bigger than any corridor of Base. Those corridor walls and floors were thick and contained a lot of steel; the ship's walls were solid alloy. He had never seen metal materialize within metal and, frankly, he didn't want to be around, even inside D-armor, when it happened. Also, there were a lot of explosives aboard, and atomic power plants, and the chance of touching off a loose atomic vortex in the very middle of Base and within a few feet of himself was not one to be taken lightly. He had already rigged a line to a master switch. Power off, with the ship's dureum catwalk as close to the floor of the corridor as the dimensions of the tube permitted, he reversed the controls and poised himself for the running headlong dive. He could not feel Radeligian gravitation, of course, but he was pretty sure that he could leap far enough to get through the interface. He took a short run, jerked the line, and hurled himself through the spaceship's immaterial wall. The ship disappeared. Going through that interface was more of a shock than the Lensman had anticipated. Even taken very slowly, as it customarily is, interdimensional acceleration brings malaise to which no one has ever become accustomed, and taking it so rapidly fairly turned Kinnison inside out. He was going to land with the rolling impact which constitutes perfect technique in such armored maneuvering. As it was, he never did know how he landed, except that he made a boiler-shop racket and that he brought up against the far wall of the corridor with a climactic clang. Beyond the addition of a few more bruises and contusions to his already abundant collection, however, he was not harmed.