A kind of grill-work along the floor gave them foothold as they passed slowly along the central corridor. Gradually it widened out. They saw row upon row of arched cross-corridors, with walls curving far overhead into interlacing spans and beams. Ceiling globes of green radiance cast a macabre glow along their route. If George Landreth had boarded this spacer, there was no evidence of it now! They walked on, staring around at the widening walls that sent back solemn echoes of their footsteps. The ship was a colossus! Curt was estimating that they'd come a good quarter of a mile already, when they reached a bulwark directly across the corridor. The wall was massive, coppery, engraven with thousands of inter-twining figures. Rikert raised his electro to burn a way through, but Lorine stopped him. "We'd best save our weapons! They're already weak." Good advice, Curt thought grimly. They were rushing headlong into trouble. It was Tor Ekkov at last who found the mechanism, a row of tiny hidden studs. There came a faint droning sound as he fumbled at them. Then slowly, ponderously, the entire wall slid upward. Weapons held in readiness, they waited. But no motion or sound came from beyond. They stepped through, found themselves in a vast circular room so startling in its content that they were held taut in amazement. * * * * * Here were machines, of every sort and description, every size and purpose. Bewildering units which somehow, seemed to form a definite pattern. Rows of them stood against the circular wall. Tier upon tier of switchboards, coils, banks of tubes, reached to the ceiling. Here, Curt knew, was the spacer's central control! But close examination showed that much of this equipment was smashed irreparably. The forward wall itself was crumpled and twisted. Then Curt noticed many bank niches about the wall, indicating that some of the machines had been removed. He frowned at that. Tor caught Curt's eye. The Martian was standing before a towering instrument. It was alien too, but there was something familiar in the arrangement of the huge power-tubes and the coils leading up to a faceted screen. "Tele-Magnum!" Tor whispered fiercely. "Or something mighty similar! Seems to work on the same etheric principle that we--" Curt cut him short. Despite everything, Tor had but one thought in mind--getting his voice through to Mars! "There's another door over here!" Rikert called. The only mechanism on this door was a two-inch disc that swung back to reveal a small opening, interlaced with silver wires. Then, in a rack near by, Jeffers spied a tiny metal tube. He lifted it out gingerly. "Take a chance," Lorine nodded. "This may be the exit we're looking for." Jeffers aimed the tube into the opening. A beam of red light lanced through the wires. They heard a faint ripple of music, then a soft whirr as the door swung back.