got set in the notion that he knew where that
pirate's treasure was. He spent all the money he had and all he could
borrow digging for it, and he never found a penny. Don't waste your
time on such foolishness. It's bad enough to be building airships and
submarines without going after treasure." Mrs. Baggert spoke with the
freedom of an old friend rather than a hired housekeeper, but she had
been in the family ever since Tom's mother died, when he was a baby,
and she had many privileges.

"Oh, this isn't any of Kidd's treasure," Tom assured her. "If we get
it, Mrs. Baggert, I'll buy you a diamond ring."

"Humph!" she exclaimed, as Tom began to hug her in boyish fashion. "I
guess I'll have to buy all the diamond rings I want, if I have to
depend on your treasure for them," and she went back to the kitchen.

"Well," went on Mr. Swift after a pause, "if we are going into the
treasure-hunting business, Tom, we'll have to get right to work. In the
first place, we must find out more about this ship, and just where it
was sunk."

"I can do that part," said Mr. Sharp. "I know some sea captains, and
they can put me on the track of locating the exact spot. In fact, it
might not be a bad idea to take an expert navigator with us. I can
manage in the air all right, but I confess that working out a location
under water is beyond me."

"Yes, an old sea captain wouldn't be a bad idea, by any means,"
conceded Mr. Swift. "Well, if you'll attend to that detail, Mr. Sharp,
Tom, Mr. Jackson and I will finish the submarine. Most of the work is
done, however, and it only remains to install the engine and motors.
Now, in regard to the negative and positive electric plates, I'd like
your opinion, Tom."

For Tom Swift was an inventor, second in ability only to his father,
and his advice was often sought by his parent on matters of electrical
construction, for the lad had made a specialty of that branch of
science.

While father and son were deep in a discussion of the apparatus of the
submarine, there will be an opportunity to make the reader a little
better acquainted with them. Those of you who have read the previous
volumes of this series do not need to be told who Tom Swift is. Others,
however, may be glad to have a proper introduction to him.

Tom Swift lived with his father, Barton Swift, in the village of
Shopton, New York. The Swift home was on the outskirts of the town, and
the large house was surrounded by a number of machi