eing a little harsh."

As Barret shrugged and didn't reply, a troubled expression crossed
Hemmingwell's face. "But at the same time," he said slowly, "if you have
any reservations, I don't suppose it would hurt to keep an eye on him."

"Yes!" agreed Barret eagerly. "That's just what I was thinking."

They reached the workbench where Troy, a small man with powerful arms
and shoulders, was working on a complicated array of wires and vacuum
tubes. He looked up, nodded casually at the two men, and indicated the
instrument.

"Here it is, Professor," he said. "All ready to go. But I had a little
trouble fitting that coil where the blueprints called for it."

"Why?" Barret demanded. "I designed that coil myself. Isn't it a little
odd that a coil I designed, and the professor O.K.'d, should not fit?"

"I don't care who designed it," said Troy easily. "It didn't fit where
the blueprint indicated. I had to redesign it."

"Now, now," said Professor Hemmingwell, sensing trouble. "Take it easy,
boys."

"Professor," Barret exploded, "I insist that you fire this man!"

"Fire me!" exclaimed Troy angrily. "Why, you space crawler, you're the
one who should be fired. I saw you come back to the hangar the other
night alone and...."

"Of course I did!" snapped Barret. "I was sent down here to get
information about--" He stopped suddenly and eyed Troy. "Wait a minute.
How could you see me down here? What were you doing here?"

"Why--I--" Troy hesitated. "I came down to check over some equipment."

"Why were you detained at the psychograph tests this morning?" demanded
Barret.

"None of your business!" shouted Troy. "I was doing my job. That's all."

"I'll bet," snapped Barret. "Professor, here is your sabotage agent. Who
are you working for, Troy?"

"None of your business," stammered Troy, seemingly confused. "I mean,
I'm not working for anyone."

"There! You see, Professor!" shouted Barret.

"I think you'd better explain yourself, Pat," said the professor,
looking troubled and suspicious. "Why were you detained so long this
morning?"

"They were asking me questions."

"What kind of questions?" demanded Barret.

"I'm not allowed to tell you."

"What were you doing here the other night?" pursued Barret. "The night
you saw me here."

"I came down to check our supplies. I knew that we were running short on
certain equipment."

"What kind of things?" demanded the professor.

"Well, the timers on the oscillators," T