Bennett placed his hands palms down on the desk. "Do you think you're the only one who worries about an alien race who can build a machine that we can't understand after ten years of investigation and study?" * * * * * The official transfer took place the following day, shortly after breakfast. Bennett called a meeting of the six department heads and announced that he would leave Titan on the next ship. It came as no surprise. "From here on, I'm just an interested observer," he said. "Dr. Lee is in charge." He paused for a moment, then went on, "I thought this would be a good time to review what's been going on most recently, and where we stand." Lee took an old pipe out of his jacket pocket and filled it while he watched them try to decide who would talk first. The six department heads all looked young and eager, he thought. Elaine was among them, of course, as head of the archeology group. After a bit of finger-pointing and head-shaking, Dr. Richards took the floor. Head of the physics section, he had one of those open, clear-eyed, crew-cut faces that would look young even after his hair turned gray. "It just so happens," he began, "that we finished a study yesterday that may be of some slight significance." From the size of his grin, Lee judged that the physicist was making a weak attempt to underplay his speech. Richards walked to the viewscreen at the far end of the room and turned a dial. The screen flickered for a moment, then showed a chart. "You remember from our last meeting," he said, "that our group finally succeeded in reaching the generating unit that powers all the machinery out there. Uh, Dr. Lee, this is something we've been working on for more than a year. The power unit is buried in the sublevel of the main building out there, and it's damned difficult to get to it without tearing out other machines. We finally wormed a man down there about a month ago." * * * * * Richards turned back to the rest of the group. "This chart shows what we've been able to learn about the power unit. Which isn't much. There's no input to it. No batteries, no solar cells, nothing. There's a fuel tank--at least, we think it's a fuel tank--that's sunk inside a cryogenic magnetic coil." Elaine spoke up. "You told us that last time. Have you been able to get into the tank?" Richards shook his head. "Not unless we break up the coil, which we don't dare try. It would probably mean destroying the power unit and stopping all the machinery. And we can't do _that_ until we're certain of what the machinery's doing." "We all know that," said Dr. Kulaki, a wiry Polynesian who headed the electronics group. "Yes. Well, we did make a very elegant experiment," Richards continued, "a variation of Cavendish's experiment to obtain the gravitational constant, in the Eighteenth Century...." "Spare the history," Dr. Kurtzman said, half-smiling.