They waited expectantly while Bob went outside. Presently they heard him up on the roof.
“Watch now!” he called down the flue.
A moment later there was a tinkling, metallic sound and sliding down the string came the big brass key of the strong room. It was guided down the chimney, and out from the fireplace, the ashes of which it cleared, across the room, until it fell on the floor, close to Mr. Beegle’s hand. There was a twitching of the cord that was fast to the little nail driven lightly into the floor. Out came the nail on the string. The cord was pulled up out of the chimney, leaving the key on the floor beside Mr. Beegle.
“Gosh!” gasped Ned.
“Easy as pie!” murmured Harry. “When you know how it’s done.”
“That was how the key trick was worked,” said Bob, as he joined his friends. “I got the idea after I’d seen that fellow in the circus movie slide down the inclined wire,” he added. “And I also saw a little hole in the floor near where Hiram lay the night he was made unconscious. It was a hole left by the nail Bill drove in for his string.
“If a man could slide down a wire, I said to myself,” a key could be made to slide the same way. I tried it with a string, passing it through the hole in the hand-end of the key, and it worked fine.
“This is what Jolly Bill did. He sneaked up, used his gas bomb, or whatever it was that overpowered Mr. Beegle, slipped in the open door of the strong room, and took the brass box. Then, to make the robbery seem mysterious, he came out and locked the door. To get the key inside he climbed the tree and slid the key down the cord he had previously prepared. Twitching out the cord and nail left not a trace except the tiny hole in the floor, of how the key got inside the locked room without an opening. The chimney flue did the trick. Though when we tried dropping the key down, finding that it only stayed in the ashes, I was puzzled for a time.”
“But could Jolly Bill climb up in a tree with his wooden leg?” asked Harry.
“Oh, he was pretty nimble—I watched him use a spade,” said Bob.