She smiled at him and went through the dining-room to the pantry door, glad to have so easily found an excuse for going there. The door stood ajar and she pushed it open to find the footman alone in it, humming a tune. “Oh, Alfred,” she said, “get a cup of tea and some bread and butter for Sergeant Birts; he’s in the hall, and has had nothing.” “Very good, miss,” returned the lad. “Hullo!” she went on with well-sustained naturalness, “how did that little window get broken?” She crossed casually to look at it. “That’s where the fellow got in who killed Sir Roger, miss,” replied Alfred with interest. “Really! That’s very interesting,” she replied. She examined the sill, the glass, the lintel and the litter on the floor with an attention she tried to make appear that of the purest curiosity. The scratches on the sill interested her most. “What are these?” she asked. “Them’s ’is boots,” Alfred answered, “’ob-nailed boots, so Birts ses; I ain’t much ’and at following such things meself.” “Nor I,” she answered slowly. Like Humblethorne, she could see no other marks suggestive of an entrance, but, unlike Humblethorne, that in itself seemed to her rather interesting. In common with all but the best brains in his profession Humblethorne had one characteristic which acted as a limitation; he was able to preserve a completely open mind at the start of an inquiry, but when he had collected sufficient facts to justify the deliberate adoption of a theory he was prone to treat as of little importance new facts which did not square with that theory; in other words, when once his thoughts had taken to running along a fixed channel facts were apt to get twisted, instead of the channel being twisted or changed to include them. He saw nothing to make probable Birts’s facile theory; he knew a great deal to make it improbable. When further search revealed clues which confirmed his theory in every respect and in addition he had the very definite identification of the stranger at the inn and John Penterton, the broken window became to him of trifling importance: he had enough to go upon with assurance without it. But to Evelyn, who embraced no theory and longed to be able to refute the conviction forced upon her, it appeared in a different light. The scratches Humblethorne soon decided had not been made by a boot, not even a hobnailed one, and it was for boot-marks that he was looking: Evelyn, who was not looking for anything, did not ignore them because to her too they seemed too regular to have been made by boots. She did not understand them and continued to wonder what had caused them. “There seem to be a good many things I don’t understand,” she thought to herself as, having reminded Alfred about the tea, she returned to the hall, “but after all that is hardly to be wondered at.” “I’ve told them to bring you some tea, Birts,” she said, “and something to eat; I expect you’ll be glad of it.” “Thank you, miss; it’s very kind of you.”