"How do you know it's a submarine?" asked the young inventor quickly, and in some confusion.

"Easy enough. When Mr. Berg thought he was pumping me, I was getting a lot of information from him. He told me about the submarine his firm was building, and, naturally, he mentioned yours. One thing led to another until I got a pretty good idea of your craft. What do you call it?"

"The Advance."

"Good name. I like it, if you don't mind speaking of it."

"We were afraid you wouldn't like it," commented Tom.

"What, the name?"

"No, the idea of going in a submarine."

"Oh," and Captain Weston laughed. "Well, it takes more than that to frighten me, if you'll excuse the expression. I've always had a hankering to go under the surface, after so many years spent on top. Once or twice I came near going under, whether I wanted to or not, in wrecks, but I think I prefer your way. Now, if you're all done, and don't mind me speaking of it, I think we'll start for your place. We must hustle, for Berg may yet get on our trail, even if he has got the wrong route," and he laughed again.

It was no small relief to Mr. Swift and Mr. Sharp to learn that Captain Weston had no objections to a submarine, as they feared he might have. The captain, in his diffident manner, made friends at once with the treasure-hunters, and he and Mr. Damon struck up quite an acquaintance. Tom told of his meeting with the seaman, and the latter related, with much gusto, the story of how he had fooled Mr. Berg.

"Well, perhaps you'd like to come and take a look at the craft that is to be our home while we're beneath the water," suggested Mr. Swift and the sailor assenting, the aged inventor, with much pride, assisted by Tom, pointed out on the Advance the features of interest. Captain Weston gave hearty approval, making one or two minor suggestions, which were carried out.