"Look, over there," Tom whispered. "That's where the oxygen is coming
from!"

Below them, Miles suddenly walked to the pipe and pulled a large lever
on its side. The roaring sound stopped immediately and the boys felt the
air pressure in the room lessen slightly.

"That blasted noise is driving me crazy," explained Miles, walking back
to the table, his voice echoing in the rock-walled cavern.

Brett, leaning over the table, was stabbing around futilely in one of
the sets of tubes in a complicated testing device. "Wish we had that
squirt Manning here," he mumbled. "He could fix these things up in no
time at all."

"I could always go back to the hide-out and get him," suggested Miles.

On the balcony Tom gripped Astro's arm tightly.

"Astro! Did you hear that?" he exclaimed.

The big cadet nodded and started to rise from their place of
concealment. Tom pulled him down. "Wait," he whispered sharply. "No use
barging in on them yet. Maybe we can find out where Roger is first."

Astro reluctantly crouched down again, his hamlike hands balled into
fists.

The two cadets watched Quent Miles and Brett work on the instruments
awhile longer. Finally Miles slammed down a pair of wire cutters on the