"I had better read up that business before they come," he said, when he had to all appearance "thought out" the subject of his reverie. "No time so good as this for doing it quietly. One never knows who is spying about in the daytime." He looked at his watch, and then went to a cupboard, where there were bundles of wood and matches and old newspapers,--for it was his habit to light his own fire occasionally when he worked unusually late at night or early in the morning. He relighted his fire now as cleverly as any housemaid in Bloomsbury, and stood watching it till it burned briskly. Then he lit a taper, and went downstairs to the professional torture-chamber. The tall horsehair chair looked unutterably awful in the dim glimmer of the taper, and a nervous person could almost have fancied it occupied by the ghost of some patient who had expired under the agony of the forceps. Mr. Sheldon lighted the gas in a movable branch which he was in the habit of turning almost into the mouths of the patients who consulted him at night. There was a cupboard on each side of the mantelpiece, and it was in these two cupboards that the dentist kept his professional library. His books did not form a very valuable collection, but he kept the cupboards constantly locked nevertheless. He took the key from his waistcoat-pocket, opened one of the cupboards, and selected a book from a row of dingy-looking volumes. He carried the book to the room above, where he seated himself under the gas, and opened the volume at a place in which there was a scrap of paper, evidently left there as a mark. The book was a volume of the _Lancet_, and in this book he read with close attention until the Bloomsbury clocks struck three. CHAPTER III. MR. AND MRS. HALLIDAY. Mr. Sheldon's visitors arrived in due course. They were provincial people of the middle class, accounted monstrously genteel in their own neighbourhood, but in nowise resembling Londoners of the same rank.