She shook her dainty head pathetically. "I am of high rank among my people. I am a priestess of our religion, which is the religion of The Great White One who rules all the sky everywhere. The Rogans" (it was the best translation Brand could make of her mental term for the slimy tall things that held them captive) "--the Rogans hold my fate over the heads of my race. Should they rebel, I would be thrown to the monster in the pen. Of course the Rogans could crush any revolt with their terrible tubes, but they do not want to kill their slaves if they can help it. They find it more effective to hold their priestesses in hostage." Brand turned from personal history to more vital subjects. "Why," he asked Greca, "are the shining red squares of metal laid everywhere over this empire of the Rogans?" "To make things light," was the reply. "When the Rogans first came to this mighty sphere, they could hardly move. Things are so heavy here, somehow. So their first thought was to drive my enslaved people to the casting and laying of the metal squares and the metal beams that connect them, in order to make things weigh less." "But how do the plates function?" * * * * * Greca did not know this, save vaguely. She tried to express her little knowledge of the scientific achievements of the savage Rogans. After some moments Brand turned to Dex and said: "As near as I can get it, the Rogans, by this peculiar red metal alloy, manage to trap and divert the permanent lines of force, the magnetic field, of Jupiter itself. So the whole red spot is highly magnetized, which somehow upsets natural gravitational attraction. I suppose it is responsible for the discoloration of the ground, too." He turned to question the girl further about this, but she had got nervously to her feet already. "I'll be taken away soon," she said. "I was brought in here only to urge you to eat the food. I must be interpreter, since the Rogans speak not with the mind, and I know their hateful tongue." "Why are they so anxious for us to eat?" demanded Dex with an uneasy frown. "So you will be strong, and endure for a long time the--the ordeal they have in store for you," faltered the girl at last. "They intend to force from you the secret of the power that drove your ship here, so they too may have command of space." "But I don't understand," frowned Brand. "They must already have a means of space navigation. They came here to Jupiter from the satellites." "Their vessels are crude, clumsy things. The journey from the nearest satellite is the limit of their flying range. They have nothing like your wonderful little ships, and they want to know how to build and power them." * * * * *