His body twisted in mid-air. He knew the others were being thrown in the same manner. Then, what an instant before had been the ceiling was now a floor beneath his feet, pressing up against him and giving him weight--and by the whistling rush of the air that tore past their shell he knew they had fallen with marvelous swiftness straight down through the throat of that lower shaft. And now what had been down was up. The ceiling of this strange room was now their floor, but Rawson was not deceived. "Acceleration," he said. "It's crowding us. The shell tends to fall faster than we do. It's like an elevator traveling downward at a swifter rate than a free falling body." * * * * * He had glimpsed the glassy-side of that well into which he knew they had been flung. He knew that the shrieks that filled the room time and again were caused by the touching of their shell's guiding and protecting bars against one glassy wall. Those sounds came always from the same side and Rawson found momentary satisfaction in his own understanding of the phenomenon. "We're falling free," he argued within his own mind, "falling toward the center of the earth. And a falling body wouldn't follow a vertical course. It would tend to hug against one wall." And by that he knew something of their speed. The necessity for it was apparent a moment later. Above his head the bull's-eyes pointing forward in the direction of their flight were faintly red. Swiftly they changed to crimson. Rawson was standing beside a window in the wall of their craft. That, too, grew quickly to an area of dazzling brightness. Slowly the heat struck in. The air in the little room was stifling. He saw the girl turn her head and give a sharp order. The man by the central post responded with another slight movement of the lever. Beneath Rawson's feet the floor pressed upward in a surge of speed that bent his knees and bore him downward. Under his hands the rod to which he clung was hot. The shining walls were dimly glowing. They were being hurled through the very heart of hell.... * * * * * And then it was past. The crimson horror beyond those windows grew dull and then black. In the blunt nose of their craft a tiny crevice must have opened. The one who drove that projectile in its shrieking flight had touched another control that Rawson had not before seen. And with a piercing shriek a thin jet of cold air drove down into the hot room. No wine could have been one-half so potent. That thin jet filled the room with buffeting whirlwinds that grew quickly cold.