Paul Arnold rubbed his eyes and sat up. Together, Harwich and the boy looked around through the crystal walls of the cage in which they were confined.
"There—there's the Tower!" young Arnold stammered at last, pointing.
It glittered in the faint morning sunshine. It was undoubtedly the same huge pinnacle that astronomers had photographed from the other moons of Jupiter. Only it was close, now, its details sharp and clear and real. Around its slender, tapered spire, thousands of feet aloft, the faintest of frosty aureoles clung; a ghostly light, like the sundogs of Earthly winter days.
"The Tower must be the source of the Ionian force envelope, Evan!" Paul Arnold offered after a moment. "That light up there at its top almost proves it."
Both men were talking vaguely, thinking vaguely, looking around vaguely. In part this must have been because of sheer wonder. Places like the Spacemen's Haven on Ganymede seemed as far away as a dream now.
An incomprehensible sense of depression was creeping over Evan Harwich, as he studied his surroundings further. There were many other cages in view, arranged in blocks, with paved alleyways between. Vegetation was thick in the evidently air-conditioned habitations. Little pools of water glistened in them daintily, strange paradox on dying Io.
And there were creatures, too. Scores of them in each cage. Strange, fragile, sluglike animals crept about aimlessly. They looked just faintly human, with their pinkish skins and manlike heads. But there was no slight shadow of intelligence in those great, sad, stupid eyes.
Harwich wasn't squeamish, but he looked at these futile animals with a certain pitying revulsion. "What kind of a nursery place have we got ourselves into, Paul?" he grumbled quizzically.
Arnold shrugged. "They're something like men, these things, aren't they?" he offered in puzzlement. "Maybe that's another unknown quantity to figure out. But this place is plenty wonderful, though. Look!"
The youth was pointing upward. Against the cold Ionian sky a flattened object was circling at low altitude. A flying machine without wings, it seemed to be. From it dangled strange webby metal arms, as it moved in a circular path, above the surrounding desert hills. It seemed to keep watch over those thousands of crystal cages in the valley. It must be a guardian of some sort.