didn't get all of us!" exclaimed Happy Harry, and there was a
savage anger in his tones.

"Keep quiet!" urged Morse.

"No, I'll not keep quiet! It's a shame that we have to take our
medicine while that trimmer, Tod Boreck, goes free. He ought to have
been with us, and he would be, only he's trying to get away with that
sparkler!"

"Keep quiet," again urged Morse.

Tom was all attention. He had caught the word "sparkler," and he at
once associated it with the occasion he had heard the men use it
before. He felt that he was on the track of solving the mystery
connected with his boat.

He looked at the men. They were the same four who had been involved in
the former theft--Appleson, Featherton, Morse and Burke. Were there
five of them? He recalled the man who had been caught tampering with
his boat--the man who had tried to bid on the ARROW at the auction.
Where was he?

"Boreck didn't get what he was after," resumed Happy Harry, "and I'm
going to spoil his game for him. Say, kid," he went on to Tom, "look
in the front part of your boat--where the gasoline tank is."

Tom felt his heart beating fast. At last he felt that he would solve
the puzzle. He opened the forward compartment. To his disappointment
it seemed as usual. Morse and the others were making a vain effort to
silence Happy Harry.

"I don't see anything here," said Tom.

"No, because it's hidden in one of those blocks of wood you use for a
brace," continued the man. "Which one it is, Boreck didn't know, so he
pulled out two or three, only to be fooled each time. You must have
shifted them, kid, from the way they were when we had the boat."

"I did," answered the young inventor, recollecting how he had taken out
some of the braces and inserted new ones, then painted the interior of
the compartment. "What is in the braces, anyhow?"

"The sparkler--a big diamond--in a hollow place in the wood, kid!"
exclaimed Happy Harry, blurting out the words. "I'm not going to let
Tod Boreck get away with it while we stay in jail."

"Take out all the braces that haven't been moved and have a look,"
suggested Mr. Sharp. Tom only had to remove two, those farthest back,
for all the others had, at one time or another, been changed or taken
away by the thief.

One of the blocks did not seem to have anything unusual about it, but
at the sight of the other Tom could not repress a cry. It was the one
that seemed to have had a hole bored in it and then