It was finally agreed that before attempting to get the books, Harvey and Mattison should make a _bona fide_ tour of inspection, by this means finding out where each man was located. Mattison reminded them that the watchman in the train shed was not to be overlooked, but they decided to chance him. “There's one thing about it,” said Mattison, smiling. “If Johnson doesn't catch us, I can discharge him for incompetency.” Shortly after midnight Harvey and Mattison started out. They found the station dark. As they tiptoed slowly along, edging close to the building, everything was silent. They reached the arched doorway, and were turning in when the glare of a bull's-eye lantern flashed into their eyes. Mattison laughed softly. “That's business,” he said. “What are you up to?” growled the man behind the lantern. “Where's Mallory?” was Mattison's answer. The man hesitated, then whistled softly. The whistle was echoed in the waiting room. In a few moments the door opened and a voice said, “What's up?” “Two chaps want Mallory.” Harvey and Mattison still stood on the stone step, looking into the lantern. They could see neither door nor man. After a short wait, evidently for scrutiny, the door closed. When it opened again, Mallory's voice said, “Close that light,” adding, “Is anything the matter, Mr. West?” “No,” replied Harvey. “We're keeping an eye open. I see your men know their business. Have you had any trouble?” “Everything is quiet. Do you care to come in?” Harvey responded by entering, with Mattison following. As they crossed the waiting room, Mallory drew their attention to a shadow near a window. “One of our boys,” he said in a low tone. “I put out all the lights. It makes it a good deal easier to watch.” Up in Mattison's office the detectives were lounging about, some dozing, some conversing in low tones. The gas burned low, and the window shutters were covered with the rugs from the President's office, to keep the light from the street. The two officials, after a glance about the room, returned to the hall. Harvey tried the door of each office, then returned to Mattison and Mallory. While they stood whispering,--for at night sound travels through an empty building,--there came the sound of a window sliding in its sash, apparently from the Treasurer's office. Mallory paused to listen, then coolly turned and continued the conversation. “What was that?” muttered Harvey. The lieutenant affected not to hear the remark. “Some one is getting into the building,” Harvey whispered. Mattison stepped lightly across the hall and, bending down, listened at the keyhole. He returned with an excited gesture. “Don't you hear it?” he asked. “No,” said Mallory. “I don't hear anything.” “Are you deaf, man?” “No, but I think I know when to hear.”