One building in particular they noticed. This was an enormous structure in the shape of a half-globe that reared its spherical height less than an eighth of a mile from the building they were in. It was situated off to their right at the foot of a vast, high-walled enclosure whose near end seemed to be formed by the right wall of their prison. They could only see it by leaning far out of the window; and it would not have come to their attention at all had they not heard it first—or, rather, heard the sound of something within it: for from it came a curious whining hum that never varied in intensity, something like the hum of a gigantic dynamo, only greater and of a more penetrating pitch.
"Sounds as though it might be some sort of central power station," said Brand. "But what could it supply power for?"
"Give it up," said Dex. "For their damned shock-tubes, perhaps, among other things—"
He broke off abruptly as a sound of sliding bolts came from the doorway. The two men whirled around to face the door, their fists doubling instinctively against whatever new danger might threaten them.
he door was opened and two of their ugly, towering enemies came in, their tubes held conspicuously before them. Behind came another figure; and at sight of this one, so plainly not of the race of Jupiter, the Earthmen gasped with wonder.
They saw a girl who might have come from Earth, save that she was taller than most Earth women—of a regal height that reached only an inch or two below Brand's own six foot one. She was beautifully formed, and had wavy dark hair and clear light blue eyes. A sort of sandal covered each small bare foot; and a gauzy tunic, reaching from above the knee to the shoulder, only half shielded her lovely figure.
She was bearing a metal container in which was a mess of stuff evidently intended as food. The guards halted and stepped aside to let her pass into the room. Then they backed out, constantly keeping Dex and Brand covered with the tubes, and closed and barred the door.
The girl smiled graciously at the admiration in the eyes of both the men—a message needing no inter-planetary interpretation. She advanced, and held the metal container toward them.