king around, or it may be Rad himself, or some one after
his chickens. Don't worry. Mr. Jackson and I can attend to it. You go
back to bed, father."

Tom spoke with such assurance that Mr. Swift believed him, and retired
to his room, just as the engineer, partly dressed, came hurrying out in
response to Tom's summons. He had his rifle, and, had the invalid
inventor seen that, he surely would have worried more.

"Come on!" whispered Tom. "Don't make any noise. I don't want to excite
my father."

"What was it?" asked the engineer.

"I don't know. Burglar alarm went off, that's all I can say until we
get to the shed."

Together the two left the house softly, and soon were hurrying toward
the aeroplane shed.

"Look!" exclaimed Mr. Jackson. "Didn't you see a light just then, Tom?"

"Where?"

"By the side window of the shed?"

"No, I didn't notice it! Oh, yes! There it is! Some one is in there! If
it's Andy Foger, I'll have him arrested, sure!"

"Maybe we can't catch him."

"That's so. Andy is a pretty slippery customer. Say, Mr. Jackson, you
go around and get Eradicate, and have him bring a club. We can't trust
him with a gun. Tell him to get at the back door, and I'll wait for you
to join me, and we'll go in the front door. Then we'll have 'em between
two fires. They can't get away."

"How about the windows?"

"They're high up, and hard to open since I put the new catches on them.
Whoever got in must have forced the lock of the door. There goes the
light again!"

As Tom spoke there was seen the faint glimmer of a light. It moved
slowly about the interior of the shed, and with a peculiar bobbing
motion, which indicated that some one was carrying it.

"Go for Eradicate, and don't make any more noise than you can help in
waking him up," whispered Tom, for they were now close to the shed, and
might be heard.

Mr. Jackson slipped off in the darkness, and Tom drew nearer to the
building that housed his Humming-Bird. There was one window lower than
the others, and near it was a box, that Tom remembered having seen that
afternoon. He planned to get up on that and look in, before making a
raid to capture the intruder.

Tom raised himself up to the window. The light had been visible a
moment before he placed the box in position, but an instant later it
seemed to go out, and the place was in darkness.

"I wonder if they've gone away?" thought Tom. "I can't hear any noise."

He listened intently. It was dark a