to some game, and I've got to find
out what it is. I wonder if I couldn't use this Foger chap?"

"He seems to have it in for this Tom Swift," Mr. Berg went on, still
talking to himself, though not so low but that Tom could hear him. "I
think I'll try it. I'll get Andy Foger to sneak around and find out
what the game is. He'll do it, I know."

By this time the auto was in working order again, and the agent took
his seat and started off.

"So that's how matters lie, eh?" thought Tom. "Well, Mr. Berg, we'll be
doubly on the lookout for you after this. As for Andy Foger, I think
I'll make him wish he'd never locked me in that tank. So you expect to
find out our 'game,' eh, Mr. Berg? Well, when you do know it, I think
it will astonish you. I only hope you don't learn what it is until we
get at that sunken treasure, though."

But alas for Tom's hopes. Mr. Berg did learn of the object of the
treasure-seekers, and sought to defeat them, as we shall learn as our
story proceeds.

Chapter Six

Turning the Tables

When the young inventor informed his father what he had overheard Mr.
Berg saying, the aged inventor was not as much worried as his son
anticipated.

"All we'll have to do, Tom," he said, "is to keep quiet about where we
are going. Once we have the Advance afloat, and try her out, we can
start on our voyage for the South American Coast and search for the
sunken treasure. When we begin our voyage under water I defy any one to
tell where we are going, or what our plans are. No, I don't believe we
need worry about Mr. Berg, though he probably means mischief."

"Well, I'm going to keep my eyes open for him and Andy Foger," declared
Tom.

The days that followed were filled with work. Not only were there many
unexpected things to do about the submarine, but Mr. Sharp was kept
busy making inquiries about the sunken treasure ship. These inquiries
had to be made carefully, as the adventurers did not want their plans
talked of, and nothing circulates more quickly than rumors of an
expedition after treasure of any kind.

"What about the old sea captain you were going to get to go with us?"
asked Mr. Swift of the balloonist one afternoon. "Have you succeeded
in finding one yet?"

"Yes; I am in communication with a man I think will be just the person
for us. His name is Captain Alden Weston, and he has sailed all over
the world. He has also taken part in more than one revolution, and, in
fact, is a soldier of