"Sightseers," said a voice from out of nowhere that made Theta scream, "will follow the white line through the door to the left. Those with business in the offices will consult the receptionist. Please proceed." Almost in a state of trance, Henry led the way along the white line. The door opened and admitted them, then a second door. Here everything was spotless, dustless, though no one had been there for years. "You are now in the generating room," the voice began again. "The humidity is zero. All dirt and dust has been removed. What you bring in with you will be gone in five minutes." They were on a balcony, looking down into a large space. On the floor below them seemed to be a huge cylinder, suspended between two metal-covered blocks. Only by the glimmering reflections from its polished surface could one tell that it was revolving. "Before you is the main generator," the voice began again. "If you look closely you will note that the armature shaft does not touch its supporting bearings. It is held in suspension by polarized barumal obtained from Mars, so there is no friction and no wear. It is powered by water reduced to hydrogen and oxygen. The excess gases are used in the hoppers and storage bins to force out the air and preserve the foods on their way to their destinations. Some gas is piped to the disposal plants, in which all organic matter is converted into fertilizer." Henry felt let down, cheated. It was just an empty building containing soundless machinery and a recorded lecture. No Old Ones. Nothing he wanted. "Now behind you," the voice began again, "you can see into the Control Room. From there every machine, store or house can have its power cut on or off. And if anything goes wrong with its circuit a button on the board flashes red until it is repaired. The glowing red button close to the window is the master switch that will shut off everything in case of an emergency, such as an earthquake." Theta pressed her nose to the glass window. "Just think," she breathed, "push that and everything stops!" Perhaps that's what happened in the other valley, thought Henry. Someone pushed the red button ... then couldn't get things going again. "Now follow the line to the next room and be seated. There you will be shown how the complex of the valley was constructed and how it operates." On entering the hall they found several rows of seats facing a large screen. Soft music began as they entered. The hall darkened and the screen lit up, showing the valley as it was before the work began. Forest mainly, a few farms scattered along the narrow bottoms. What startled Henry was that they were _above_ the valley, looking down as they seemed to drift through the air. So the old tales were right! The Old Ones could fly through the air! Here was proof of it. He sat on the edge of his seat, breathing hard, waiting to see the Old Ones, giant of stature, who could tear a tree out of the ground or shovel away a mountain.