"We did, but—"

"That was my island!" exclaimed Mr. Peterson. "The mine was in that mountain, but an earthquake had covered it. I should never have found it but for you. That shot you accidentally fired ripped the mountain apart. My men and I were fortunately at the base of it then, but we sure thought our time had come when that shell struck. It went right over our heads. But it did the business, all right, and opened up the old mine. Tom, your father won't lose his money, we'll all be rich. Oh, that was a lucky shot! I knew it was your cannon that did it."

"I'm glad of it!" answered the young inventor, heartily. "Glad for your sake, Mr. Peterson."

"You must come and see the mine—your mine, Tom, for it never would have been rediscovered had it not been for your giant cannon, that made the longest shot on record, so I'm told."

"We will come, Mr. Peterson, just as soon as I close up matters here."

It did not take Tom long to do this. His type of cannon was formally accepted as a defense for the Panama Canal, and he received a fine contract to allow that type to be used by the government. His powder and projectiles, too, were adopted.

Then, one day, he and Ned, with Koku and Mr. Damon, visited the scene of the great shot. As Mr. Peterson had said, the whole top of the mountain had been blown off by the explosive shell, opening up the old mine. While it was not quite as rich as Mr. Peterson had glowingly painted, still there was a fortune in it, and Mr. Swift got back a substantial sum for his investment.

"And now for the good old U. S. A.!" cried Tom, as they got ready to go back home. "I'm going to take a long rest, and the only thing I'm going to invent for the next six months is a new potato slicer." But whether Tom kept his words can be learned by reading the next volume of this series.

"Bless my hand towel!" cried Mr. Damon. "I think you are entitled to a rest, Tom."

"That's what I say," agreed Ned.