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 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.