“Well, we solved the mystery of the center of the earth,” remarked Jack, one evening, when they were gathered in the old shack where so many wonderful adventures had been planned.
“Yes, we did,” said Mr. Henderson. “And no one else is ever likely to go there.”
“Why?”
“Because the only way of getting there was destroyed by the earthquake, and no one could ever force his way down through that upward-shooting column of water.”
“That’s so. Well, we have the diamonds, anyway,” spoke Mark. “They ought to make us rich.”
And the jewels did, for the stones proved to be of great value, even though the adventurers had saved only a few of the many they found in the ruined temple.
But there was money enough so that they all could live in comfort the rest of their lives. As the professor was getting quite old, and incapable of making any more wonderful inventions, he closed up his workshop and settled down to a quiet life. As for Washington, Andy, and Bill and Tom, they invested their money received from the sale of the diamonds in different business ventures, and each one did well.
“I am going in for a good education,” said Jack to Mark.
“Just what I am going to do,” answered his chum. “And after we’ve got that——” He paused suggestively.
“We’ll go in for inventing airships, or something like that, eh?”