They crept up the passage together avoiding touching hands lest the ring of the metal should warn the sentry. As they approached they could see the room he looked out on was one of the familiar blue-domed halls; the passage ended sharply some six feet above its floor ("Taking no chances on more escapes" thought Sherman) and that the hall was of enormous size. There were machines in one corner of the floor. In another stood one of the green globes, half finished, with spidery trellises of red metal outlining what would be the surface of the sphere. Around it helmeted mechanical men came and went busily. The rest of the hall, for all its vast extent, was completely empty. At the far end was a row of doors; high on the far side an opening that looked like a door but had no obvious purpose. This much they saw; then the sentry stirred as though to turn, and with a quick patter of feet, they were upon him. Before he had time to turn around Ben Ruby launched himself in a perfect football tackle for his legs, bringing the ape-man down with a crash. As he fell, Sherman snatched at the helmet, and Gloria the light-gun, which had dropped from his fingers, while Murray pinioned the struggling creature's arms. In a moment Sherman found the finger-holes in the helmet, pressed, and it came loose in his hands while the ape-man ceased to struggle. "Let him up now, folks," said Sherman, "give him a swift kick and point him toward the door. He won't come back." And he rapidly adjusted the thought-helmet to his own head. The Lassan at the other end was evidently disturbed. He had received the sound of the crash from the ape-man's brain and was asking querulously what it meant. "What has happened?" the thought demanded insistently. "What is it that struck you? Have the fighting machines returned? Show a picture of what you see. Are the slaves escaping?" "Everything's all right," Sherman sent back. "Something broke loose down below and I stumbled trying to look at it." He closed his eyes, forming a mental picture of the hall, with everything in order, then one of the passage, and reached up and detached the helmet, motioning to Murray for the knife. An instant's sawing and the device short-circuited with a fizzing of blue sparks. "That will give that one a headache for a while," he remarked. "We'll have to hurry, though. When he comes to he'll investigate and then there'll be trouble." "What's that?" asked Gloria, pointing across the hall at the aperture high up in the wall. A gleaming beak had been thrust out and the bright, intelligent eye of one of the dodo-birds was regarding them malevolently from the opening. "Shoot, quick!" said Sherman, "For God's sake! They're telepathic. They'll have every Lassan in the place after us."