Tom looked slightly incredulous, but said nothing.

Then followed busy days. The submarine Advance, which had made
several successful trips, as related in the book bearing the
title, "Tom Swift and His Submarine Boat," was hauled into dry
dock and the work 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