wn globe, and had been
forced to find more territory.

They had made captive the entire population of the satellite.
Then--for like all dangerous vermin they multiplied rapidly--they had
overflowed to the first and fifth satellites--the others were
uninhabitable--and finally to the dangerous surface of Jupiter itself.
Everywhere they had gone, they had taken droves of Greca's people to
be their slaves, "and the source of their food," added Greca, with a
shudder; a statement that was at the moment unintelligible to the two
men.

* * * * *

Brand stared sympathetically at her. "They treat them very badly?" he
asked gently.

"Terribly! Terribly!" said Greca, shuddering again.

"But you seem quite privileged," he could not help saying.

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