flying from his hand and
sailing into the sky. His shoes clung momentarily to the surface, but
their magnetic grip was too weak, and they loosened. He kicked out
wildly, falling away into the emptiness of outer space--a space which
had a moment ago been a sky and had suddenly turned into a bottomless
pit.

He fell backward, seized momentarily by terror. He was brought up short
by his rope. It held, and he grabbed it and hung on.

Something had changed. Somebody had altered the ship's drive. The ship
was no longer on free fall; it was on gravity drive--and going backward!
Not driving toward Jupiter under added acceleration, but fighting to
reduce its fall, to stop its drive, to fly away from Jupiter!

In his earphones there was a jumble of sounds. He heard Ferrati yelling
and realized that he, too, must be falling away from the ship, saved
only by a rope. And the voice of Haines--plastered flat against the
surface, the ship driving upward against him.

Vague noises emanated from the control room. Evidently no one was at the
commander's mike. He called into it, adding his voice to those of his
comrades.

After several agonizing minutes, a voice came over the radio. It was
Russell Clyde's and it was excited and angry. "Hold on out there as long
as you can! Lockhart's been knocked unconscious! We're trying to get
into the engine room and take back control!"

Perplexed, Burl shouted, "Who's in the engine room? Take control from
whom?"

There was another pause as he heard sounds of pounding, as if someone
were trying to hammer open a metal panel. Then Russ's voice came on
again. "Its Boulton! He came to suddenly, sneaked up here, knocked out
the commander, and climbed up into the Zeta-ring chamber! Caton was down
below--and Boulton's locked the trap door and is running the drive. He's
reversed our route, away from Jupiter, and into outer space! Boulton's
apparently gone crazy! And we can't get in to stop him!"

Burl, suspended over an abyss, clung to the end of the taut, thin nylon
line, as the ship pulled him helplessly along into the uncharted depths
of infinity, with a mad-man at the controls.

Chapter 13. _The Pole of Callisto_

Burl surveyed his position. Judging from the apparent weight of his
body, Boulton was decelerating the ship at a little less than one
gravity. The nylon cord was hooked into a bolt near the center of the
ship. It would be possible for Burl to climb up it and reach a firmer
gr