The door closed. He was within the shell, standing on a smooth metal floor. The others were beside him. Dully he wondered what wild adventure was ahead. * * * * * He had expected--he hardly knew what. But there should have been machinery of some sort. If this weird balloon thing was actually to carry them, there must be some mechanism, some propelling power. And instead he saw nothing but the shining walls of the circular room and at the exact center, reaching from floor to ceiling, a six-inch metal post that thickened to a boxlike form on a level with his eyes. There was a plate on the side of that box, a cover, and clamps that held it in place, and on an adjoining side two little levers, one near the top of the box, the other near the bottom. His one all-inclusive glance showed him bull's-eye windows in the ceiling. There were more of them in the floor. One curved bar, circling the room, was mounted on brackets against the wall. They were telling him by signs that he was to put his hands on it and hang on. One of the men was beside that central post. He too gripped at a projecting hand-hold. His other hand was on the lower lever. Rawson knew his disappointment was unreasonable, but his weary mind was tired of mysteries. Some understandable bit of machinery would have been reassuring. And then in his next thought he asked himself what difference did it make. If this childish balloon thing were really capable of carrying them somewhere, what of it? It could only mean more of this hideous inner world that grew more unbearably fantastic with each new experience. His life had been saved. True, but for what end? The girl's eyes were upon him, reading the expression on his face. She smiled encouragingly. Then Rawson's hands tightened upon the metal bar. The man who stood by the central post had moved one lever the merest trifle. Rawson felt the floor lifting beneath him. Then the shell, like a bubble of metal, pitched and tossed as the powerful air currents caught it. * * * * * His own lightness saved him from injury. He gripped the bar and held himself free of the wall. The round top of their strange craft grated against the domed roof. Then again the ship steadied and seemed motionless, and Rawson knew they had slipped up into the still air of that upper shaft. For one wild instant, filled with impossible hope, Rawson saw this as a means of ascent to his own world. Then reason tore those wild hopes to shreds. "It's closed up above," he thought. "It must be. That's why it sounded that way. That's why the air drove off through those side passages." The next instant held no time for thought. Rawson's whole attention was concentrated upon the bar to which he clung. For, quicker than thought, the metal shell, the little cylindrical world in which he and these others were, fell swiftly beneath them.