"I had a hard time getting the final papers," said Mr. Houghton, "and that's what took me so long. But now, Uncle, the boiling spring is yours, and you needn't worry any more."
"How can it be hot water in the Winter time?" asked Bob.
"Well, that's one of the mysteries of Nature," said the former hermit. "I suppose the waters must come from deep down in the earth, and the wise men tell us that inside the earth are raging fires. I don't know about that, but I do know my medical spring will cure rheumatism. And I guess now, everything is explained."
"No, not everything," said Sammy quickly.
"Eh?" asked the old man.
"We found a secret room in the old mansion," went on Sammy, "and it's a counterfeiters' den, I'm sure. We thought you were going there, Mr. Addison, that's why we followed you.
"And while we were in there," Sammy went on, "there was an explosion. We thought someone was shooting at us, and we ran out. That has to be explained yet."
"That's so!" exclaimed Mr. Jessup. "I've got to look into that."
Mr. Houghton laughed.
"It won't take much of an explanation to do away with that mystery," he said. "If you'll come with me I'll show you all about it. I fancy you stumbled across one of my fads. Will you come, Uncle Frank?"