"That," continued Quinn, as he tossed another pink wrapper into the wastebasket, "I consider the simplest and cleverest scheme to beat the government that I ever heard of--better even than Cochrane's plan in connection with the robbery of the Philadelphia mint, because it didn't necessitate any outside preparation at all. The right job, a piece of gum, and there you are. But you may be sure that whenever an important letter disappears nowadays, one of the first places searched by the Postal Inspection operatives is the lower side of the desks and tables. You can't get away with a trick twice in the same place." XII "THE DOUBLE CODE" It was one night in early fall that Bill Quinn and I were browsing around the library in the house that he had called "home" ever since a counterfeiter's bullet incapacitated him from further active work in the Secret Service. Prior to that time he had lived, as he put it, "wherever he hung his hat," but now there was a comfortable little house with a den where Quinn kept the more unusual, and often gruesome, relics which brought back memories of the past. There, hanging on the wall with a dark-brown stain still adorning the razorlike edge, was a Chinese hatchet which had doubtless figured in some tong war on the Coast. Below was an ordinary twenty-five-cent piece, attached to the wall paper with chewing gum--"just as it once aided in robbing the Treasury of nearly a million dollars," Quinn assured me. In another part of the room was a frame containing what appeared to be a bit torn from the wrapping of a package, with the canceled stamp and a half-obliterated postmark as the only clues to the murder of the man who had received it, and, beside the bookcases, which contained a wide range of detective literature, hung a larger frame in which were the finger prints of more than a score of criminals, men bearing names practically unknown to the public, but whose exploits were bywords in the various governmental detective services. It was while glancing over the contents of the bookcase that I noted one volume which appeared strangely out of place in this collection of the fictional romances of crime. "What's this doing here?" I inquired, taking down a volume of _The Giant Raft_, by Jules Verne. "Verne didn't write detective stories, did he?" "No," replied Quinn, "and it's really out of place in the bookcase. If possible, I'd like to have it framed and put on the wall with the rest of the relics--for it's really more important than any of them, from the standpoint of value to the nation. That quarter on the wall over there--the one which figured in the Sugar Fraud case--cost the government in the neighborhood of a million dollars, but this book probably saved a score of millions and hundreds of lives as well. If it hadn't been for the fact that Thurber of the Navy Department knew his Jules Vernes even better than he did his Bible, it's quite possible that--