cadets were studying secretly. But they all felt fairly safe, for the
cadet watch officers on each floor were anxious to study themselves and
turned a blind eye. Even the Solar Guard officer of the day, in charge
of the entire dormitory, was sympathetic to their efforts and made a
great deal of unnecessary noise while on his evening rounds.

His brown curly hair falling over his forehead, Tom Corbett frowned in
concentration as he kept the earphones of his study machine clamped
tightly to his ears and listened to a recorded lecture on astrophysics
as it unreeled from the spinning study spool. As command cadet of the
_Polaris_ unit, Tom was required to know more than merely his particular
duty as pilot of a rocket ship. He had to be familiar with every phase
of space travel, with a working knowledge of the duties of all his unit
mates.

Astro, the power-deck officer of the unit, paced back and forth between
the bunks like a huge, hulking bear, muttering to himself as he tried to
memorize the table of reaction times for rocket motors. Though the huge
Venusian cadet was a genius at all mechanical tasks, and able to work
with tools the way a surgeon worked with instruments, he had great
difficulty in learning the theories and scientific reasons for all the
things he did instinctively. Suddenly Astro stopped, looked at his
chronometer, then turned to Tom.

"Hey, Tom!" he called. "Where's that jerk, Manning?"

"Huh?" replied Tom, lifting one of the earphones from his ears. "What
did you say, Astro?"

"Where's Manning?" reiterated Astro. "It's ten minutes after lights