Tom Swift and His Giant Cannon

"Now, see here, Mr. Swift, you may think it all a sort of dream, and imagine that I don't know what I'm talking about; but I do! If you'll consent to finance this expedition to the extent of, say, ten thousand dollars, I'll practically guarantee to give you back five times that sum "I don't know, Alec, I don't know," slowly responded the aged inventor. "I've heard those stories before, and in my experience nothing ever came of them. Buried treasure, and lost vessels filled with gold, are all well and good, but hunting for an opal mine on some little-heard-of island goes them one better." "Then you don't feel like backing me up in this matter, Mr. Swift?" "No, Alec, I can't say I do. Why, just stop and think for a minute. You're asking me to put ten thousand dollars into a company, to fit out an expedition to go to this island-somewhere down near Panama, you say it is-and try to locate the lost mine from which, some centuries ago, opals and other precious stones came. It doesn't seem reasonable.