rk of
overhauling her begun. Tom put his best men to work, and, after a
consultation with his father, decided on some radical changes in the
craft.

"Tom, my boy," said the aged Mr. Swift, "I wish you weren't going on
this trip."

"Why, Dad?" asked the young inventor.

"Because I fear something will happen. We don't really need this money,
and suppose--suppose--"

"Oh, I'm not worrying, Dad," was the answer. "I've taken worse risks
than this, many a time. I'm really doing it as a favor to Mr. Damon.
He's got too much money invested to let him lose it. And we can use a
million dollars ourselves. It will enable me to put in operation a plan
to pension our workmen. I've long had that in mind, but I've never had
enough capital to carry it out."

"Well, of course, Tom, that's a worthy object, and I won't make any
further objections. But take my advice, and strengthen the submarine."

"Why, Dad?" asked Tom in some surprise. "Because you'll find the water
there of a greater depth than you think," was the answer. "I know you
have the official hydrographic charts, but there's a mistake, I'm sure.
I once made a study of that part of the ocean, and there are currents
there at certain seasons of the year that no one suspects, and deep
caverns that aren't charted. If the Pandora lies in one of these
you'll need a great strength of walls to your submarine to withstand
the pressure of deep water."

The craft Tom Swift proposed to use in searching for the treasure ship
Pandora was of the regular cigar-shape, but inside it had many special
features. It was more comfortable than the usual submarine, not being
intended for fighting, though it did carry guns and a torpedo tube. Tom
intended renaming the craft, which had been called Advance, and one
day, when there had been some discussion as to what the undersea craft
ought to be called, Ned explained:

"Why don't you name it after her?"

"After whom?" inquired Tom, in some surprise, looking up from a letter
he was writing.

"Your friend and future wife, Mary Nestor," answered Ned. "I'm sure
she'd appreciate it."

"That isn't such a bad idea," conceded Tom musingly. "The only thing
about it is that I don't want Mary's name bandied about that way."

"Use her initials, then," suggested Ned.

"How do you mean?"

"Why not call it the M. N. 1.? Isn't that a good name?"

"The M. N. 1." mused Tom. "Not so bad. If the N. C. 4 flew over the
ocean the M. N. 1 ought to be able