Down the attic stairs they rushed, and they never paused until they were safely out of the old house. Then, some distance off, the fright left them, and they halted to look back.
"What happened?" panted Sammy.
"It was an explosion," decided Frank.
"No, those counterfeiters must have come back and shot at us," gasped Bob.
"Go on! You're worse than Sammy," said Frank, who was more calm than his chums. "It was some sort of explosion. Maybe it was powder the men left there, or it might have been some of the chemicals they use, in whatever they do, whether it's making bad money, or something else. Anyhow it was just an explosion. There was no one in that room but ourselves."
"Well, I guess that's right," agreed Bob, when he had thought it over a bit. "But who exploded it?"
"Maybe I did," admitted Sammy, slowly. "I know just before that flash and puff came, I touched one of the wires on those telescope things. There was a click, and it went off—all at once!"
"I should say it did," spoke Frank. "It went off fast enough."
"And there was an awful lot of smoke!" added Bob.