"You know how the fresheners work!" said Sandringham. "They pump sea-water in at one end, and at the other one pipe yields fresh water, and the other heavy brine. They dump the heavy brine back overboard and the fresh water's pumped up and distributed through the irrigation systems." "It's too bad some of the salts weren't stored," said Bordman. "Could a freshener be started up again?" Sandringham stared. Then he said: "Oh, the civilians would love that! Now if any man started up a water-freshener, the civilians would kill him and smash it!" "But I think we'll need one. We'll want to irrigate some of the Reserve area." "My God! What for?" demanded Sandringham. He paused. "No! Don't tell me! Let me try to work it out." There was silence. The brown dog blinked at Bordman. He held out his hand. The dog came sedately to him and bent his head to be scratched. After a considerable time, the Sector Chief growled: "I give up. Do you want to tell me?" Bordman nodded. He said: "In a sense, the trouble here is that there's a swamp underground, made by irrigation. It slides. It's really a swamp upside down. On Soris II we had a very odd problem, only the swamp was right-side-up there. We'd several hundred square miles of swamp that could be used if we could drain it. We built a soil-dam around it. You know the trick. You bore two rows of holes twenty feet apart and put soil-coagulant in them. It's an old, old device. They used it a couple of hundred years ago back on Earth. The coagulant seeps out in all directions and coagulates the dirt. Makes it water-tight. It swells with water and fills the space between the soil-particles. In a week or two there's a water-tight barrier, made of soil, going down to bed-rock. You might call it a coffer-dam. No water can seep through. On Soris II we knew that if we could get the water out of the mud inside this coffer-dam, we'd have cultivable ground." Sandringham said skeptically: "But it called for ten years' pumping, eh? When mud doesn't move, pumping isn't easy!" "We wanted the soil," said Bordman. "And we didn't have ten years. The Soris II colony was supposed to relieve population-pressure on another planet. The pressure was terrific. We had to be ready to receive some colonists in eight months. We had to get the water out quicker than it could be pumped. And there was another problem mixed up with it. The swamp vegetation was pretty deadly. It had to be gotten rid of, too. So we made the dam and--well--took certain measures, and then we irrigated it. With water from a nearby river. It was very ticklish. But we had dry ground in four months, with the swamp-vegetation killed and turning back to humus." "I ought to read your reports," said Sandringham dourly. "I'm too busy, ordinarily. But I should read them. How'd you get rid of the water?" Bordman told him. The telling required eighteen words. "Of course," he added, "we picked a day when there was a strong wind from the right quarter."