When the Travelers from Outer Space dug into the pile of moldering rock, they found the metal capsule their senses had told them was there. Battered and corroded though it was, the shadow vibrations showed that it had once been smooth and shiny. As smooth, shiny and impervious to wear as Twentieth Century Earth technology could make it. At the time the Mayor of Chicago had ceremoniously tossed a handful of lake sand into the hole, had his picture taken smiling against the skyline, and had moved