"The duplicator will run on direct current," said Keg. "They just have a set of fully charged batteries recorded. They have a set in spare. When battery one runs down, battery two takes its place, and the first thing run off is a spare battery number three, and so on. The exhausted batteries are dumped into the matter bank and re-converted. But it is not a real luxury, running on batteries. They need the high power that your stations will deliver. They need the telephone and the radio which your men can maintain. Go and seek the officials of the various companies, and tell them what you want to do. Work at it, Norton. There will be a lot of men in your gang that would rather do something else. Eventually you will be able to release them to do the jobs you are best fitted for. Until we get a medium of exchange, it is a job proposition. I'll add this inducement: 'The medical service of Fabriville is yours--providing that you and your men will work with us.'" Norton thought for a moment. "Done," he said shortly. "Can you give us warmth and food until we take care of the details?" "That we can." A stilted monster ran out from Fabriville under its own power. Four great girdered legs supported a housing the size of a freight car, and the legs moved on small tractor threads. Out it came, and it paused just outside the gate. A faint violet glow emerged from the bottom of the housing, and the whirling-skirling of Martian sands obscured the vastness of the space between the legs of the monster machine. It moved again, and the original dust settled to disclose a very small but completely finished and furnished house. Around the encircling fence went the monstrous duplicator, and at each stop it dropped the carbon copy of the original house. Hour after hour it hummed, and when it completed the circle, Norton's mob was housed, fed and clothed. And Norton knew that the "fence-building" job was but a test. For if the thing could build a house-- * * * * * Venus Equilateral resounded and re-echoed from the force of the blast. It rocked, and precession tilted it away from its true north and south axial positioning. Men raced along the car-way to the blister laboratory and Channing led the wild rush. The blister was gone. A shaken Wes Farrell clung to a stanchion, his face white behind the spacesuit mask. They fished him out of the wreckage and took him inside. "What happened?" asked Don. "Was making artificial elements," explained Wes. "Far outside of the Periodic Chart. I'd been stacking them over in a corner--they come in six-inch cubes, you know. But the last one--_Bang!_" Channing shook his head. "That's dangerous," he said solemnly. "If you had a six-inch cube of every known element, would you stack 'em all side by side?" "It might be all right--until you came to putting phosphorus on top of a hunk of iodin," said Walt.