For a considerable time, nothing save barren, ocherous desert was in view. Then Larry's weird captor flew near a strange city. A city of green metal. The buildings were most fantastic--pyramids of green, crowned with enormous, glistening spheres of emerald metal. An impassable wall surrounding the city. Larry had expected the monster to drop into the city. But it carried him on, and finally settled to the ground several miles beyond. The green tentacles released him, as the thing landed, and he sprawled beside it, dizzy after his strange flight. As Larry staggered uncertainly to his feet, he saw that the monster had released him in an open pen. It was a square area, nearly fifty yards on each side, and fenced with thin posts or rods of green metal, perhaps twenty feet high. Set very close together, and sharply pointed at the top, they formed a barrier apparently insurmountable. In the center of the pen was a huge and strange machine, built of green metal. It looked very worn and ancient; it was covered with patches of bluish rust or corrosion. At first it looked quite strange to Larry; then he was struck by a vaguely familiar quality about it. Looking closer, he realized that it was a colossal steam hammer! Its design, of course, was unfamiliar. But in the vast, corroded frame he quickly picked out a steam chest, cylinder, and the great hammer, weighing many tons. He gasped when his eyes went to the anvil. A man was chained across it. A man in torn, grimy clothing, fastened with fetters of green metal upon wrists and ankles, so that his body was stretched beneath the massive hammer. He seemed to be unconscious; upon his head, which was turned toward Larry, was a red and swollen bruise. The monster which had dropped Larry within the pen rose again into the air. And Larry started forward, trying to remember just what Agnes had told him of a machine to which the monsters sacrificed. This must be the machine--this ancient steam hammer! As he moved forward, Agnes came into view. * * * * * She walked around the massive base of the great machine, carrying a bowl filled with a fragrant brown liquid. She stopped at sight of Larry, and uttered a little cry. The bowl fell from her hands, and the fragrant liquid splashed out on the ground. Her brown eyes went wide with delighted surprise; then a look of pain came into them. "Larry, Larry!" she cried. "Why did you come?" "To get you," he answered, trying to speak as lightly as he could. "And the best way I knew to find you was to let one of the monsters bring me. Cheer up!" But even to himself, his voice had a tone of discouragement. She smiled wanly. "I don't see anything to be cheerful about." Her small face was set and a little white. "Dr. Whiting is going to be smashed under the hammer of this dreadful machine, whenever the steam is up. Then it is my turn. And yours. That's nothing to laugh about." "But we aren't smashed yet!" Larry insisted.