"The City of Space is in a cylinder," Captain Smith said. "Roughly five thousand feet in diameter, and about that high. It is built largely of meteoric iron which we captured from a meteorite swarm—making navigation safe and getting useful metal at the same time. The cylinder whirls constantly, with such speed that the centrifugal force against the sides equals the force of gravity on the earth. The city is built around the inside of the cylinder—so that one can look up and see his neighbor's house apparently upside down, a mile above his head. We enter through a lock in one end of the cylinder."
A vast disk of dull black metal was now visible a few yards outside the vitrolite panels. A huge metal valve swung open in it, revealing a bright space beyond. The Red Rover moved into the chamber, the mighty valve closed behind her, air hissed in about her, an inner valve was opened, and she slipped into the City of Space.
A huge metal valve swung open in it, revealing a bright space beyond.... An inner valve was opened, and Red Rover slipped into the City of Space.
They were, Bill saw, at the center of an enormous cylinder. The sides, half a mile away, above and below them, were covered with buildings along neat, tree-bordered streets, scattered with green lawns, tiny gardens, and bits of wooded park. It seemed very strange to Bill, to see these endless streets about the inside of a tube, so that one by walking a little over three miles in one direction would arrive again at the starting point, in the same way that one gets back to the starting point after going around the earth in one direction.
At the ends of the cylinder, fastened to the huge metal disks, which closed the ends, were elaborate and complex mechanisms, machines strange and massive. "They must be for heating the city," Bill thought, "and for purifying the air, for furnishing light and power, perhaps even for moving it about." The lock through which they had entered was part of this mechanism.
In the center of each end of the cylinder hung a huge light, seeming large and round as the sun, flooding the place with brilliant mellow rays.
"There are five thousand people here," said Captain Smith. "The Prince has always kept the best specimens among his captives, and others have been recruited besides. We are self-sustaining as the earth is. We use the power of the sun—through our vitalium batteries. We grow our own food. We utilize our waste products—matter here goes through a regular cycle of life and death as on the earth. Men eat food containing carbon, breathe in oxygen, and breathe out carbon dioxide; our plants break up the carbon dioxide, make more foods containing the same carbon, and give off the oxygen for men to breathe again. Our nitrogen, our oxygen and hydrogen, go through similar cycles. The power of the sun is all we need from outside."