ng the city, having walked along as they talked.
There were still some sand dunes near the road, and they kept on the
side of these, nearest the beach, where they could watch the breakers.

"But you haven't told me where you are going," went on Mr. Damon, after
blessing a few dozen objects. "Where do the Government trials take
place?"

"Well," replied the lad, "to be frank with you, we have abandoned our
intention of trying for the Government prize."

"Not going to try for it? Bless my slippers! Why not? Isn't fifty
thousand dollars worth striving for? And, with the kind of a submarine
you say you have, you ought to be able to win."

"Yes, probably we could win," admitted the young inventor, "but we are
going to try for a better prize."

"A better one? I don't understand."

"Sunken treasure," explained Tom. "There's a ship sunk off the coast of
Uruguay, with three hundred thousand dollars in gold bullion aboard.
Dad and I are going to try to recover that in our submarine. We're
going to start day after to-morrow, and, if you like, you may go along."

"Go along! Of course I'll go along!" cried the eccentric man. "But I
never heard of such a thing. Sunken treasure! Three hundred thousand
dollars in gold! My, what a lot of money! And to go after it in a
submarine! It's as good as a story!"

"Yes, we hope to recover all the treasure," said the lad. "We ought to
be able to claim at least half of it."

"Bless my pocketbook!" cried Mr. Damon, but Tom did not hear him. At
that instant his attention was attracted by seeing two men emerge from
behind the sand dune near which he and Mr. Damon had halted
momentarily, when the youth explained about the treasure. The man
looked sharply at Tom. A moment later the first man was joined by
another, and at the sight of him our hero could not repress an
exclamation of alarm. For the second man was none other than Addison
Berg.

The latter glanced quickly at Tom, and then, with a hasty word to his
companion, the two swung around and made off in the opposite direction
to that in which they had been walking.

"What's the matter?" asked Mr. Damon, seeing the young inventor was
strangely affected.

"That--that man," stammered the lad.

"You don't mean to tell me that was one the Happy Harry gang, do you?"

"No. But one, or both of those men, may prove to be worse. That second
man was Addison Berg, and he's agent for a firm of submarine boat
builders who are rivals of dad'