ith Tom when he
got the note from the balloonist. "We'll get to the bottom of this
mystery after a while, Tom."

Delaying a few days, to make the final changes in his aeroplane, Tom
and Mr. Damon departed for Hampton one morning. They thought first of
going in the Butterfly, but as they wanted to keep their mission as
secret as possible, they decided to go by train, and arrive in the town
quietly and unostentatiously. They got to Hampton late that afternoon.

"What's the first thing to be done?" asked Mr. Damon as they walked up
from the station, where they were almost the only persons who alighted
from the train.

"Go to the hotel," decided Tom. "There's only one, I was told, so
there's not much choice."

Hampton was a quiet little country town of about five thousand
inhabitants, and Tom soon learned the address of Mr. Bentley, Andy's
uncle, from the hotel clerk.

"What business is Mr. Bentley in?" asked Tom, for he wanted to learn
all he could without inquiring of persons who might question his
motives.

"Oh, he's retired," said the clerk. "He lives on the interest of his
money. But of late he's been erecting some sort of a building on his
back lot, like a big shed, and folks are sort of wondering what he's
doing in it. Keeps mighty secret about it. He's got a young fellow
helping him."

"Has he got red hair?" asked Tom, while his heart beat strangely fast.

"Who? Mr. Bentley? No. His hair's black."

"I mean the young fellow."

"Oh! his? Yes, his is red. He's a nephew, or some relation to Mr.
Bentley. I did hear his name, but I've forgotten it. Sandy, or Andy, or
some such name as that."

This was near enough for Tom and Mr. Damon, and they did not want to
risk asking any more questions. They turned away to go to their rooms,
as the clerk was busy answering inquiries from some other guests. A
little later, supper was served, and Tom, having finished, whispered to
Mr. Damon to join him upstairs as soon as he was through.

"What are you going to do?" asked the eccentric man.

"We're going out and have a look at this new shed by moonlight,"
decided Tom. "I want to see what it's like, and, if possible, I want to
get a peep inside. I'll soon be able to tell whether or not Andy is
using my stolen plans."

"All right. I'm with you. Bless my bill of fare! But we seem to be
doing a lot of mysterious work of late."

"Yes," agreed Tom. "But if you have to bless anything to-night, Mr.
Damon, please whisper it