Happening to mention the dog here, he found that Mr Bright was partially acquainted with the incident. "It was down these stairs it ran," he said, "and was knocked on the head in this very room by the policeman. No one knows where he took the body to, but he went out at that door, in the direction, it is supposed, of the boiler-house." The detective had at last got hold of a clew. He was what is styled, in a well-known game, "getting warm." "Let us visit the boiler-house," he said. Again, for the nonce, he became an engineer. Like Paul, he was all things to all men. He was very affable to the genial stoker, who was quite communicative about the boilers. After a time the detective referred to the dog, and the peculiar glance of the stoker at once showed him that his object was gained. "A policeman brought it?" he asked quietly. "Yes, a policeman brought it," said the stoker suspiciously. The man in grey soon, however, removed his suspicions and induced him to become confidential. When he had obtained all the information that the stoker could give--in addition to poor Floppart's collar, which had no name on it, but was stamped with three stars on its inside--the detective ceased to make any further inquiries after mad dogs, and, with a disengaged mind, accompanied Mr Bright through the remainder of the basement, where he commented on the wise arrangement of having the mail-bags made by convicts, and on the free library, which he pronounced a magnificent institution, and which contained about 2000 volumes, that were said by the courteous librarian to be largely used by the officials, as well as the various newspapers and magazines, furnished gratuitously by their proprietors. He was also shown the "lifts," which raised people--to say nothing of mails, etcetera--from the bottom to the top of the building, or _vice versa_; the small steam-engine which worked the same, and the engineer of which--an old servant--was particularly impressive on the peculiar "governor" by which his engine was regulated; the array of letter stampers, which were kept by their special guardian in immaculate order and readiness; the fire-hose, which was also ready for instant service, and the firemen, who were in constant attendance with a telegraphic instrument at their special disposal, connecting them with other parts of the building. All this, and a great deal more which we have not space to mention, the man in grey saw, admired, and commented on, as well as on the general evidence of order, method, regularity, neatness, and system which pervaded the whole place. "You manage things well here," he said to his conductor at parting. "We do," responded Mr Bright, with an approving nod; "and we had need to, for the daily despatch of Her Majesty's mails to all parts of the world is no child's play. Our motto is--or ought to be--`Security, Celerity, Punctuality, and Regularity.' We couldn't carry that out, sir, without good management.--Good-bye."