Mr. Drake turned very pale, whether from fear, or from the strong cigar, I do not know, but after a few minutes he recovered himself, and at Keys’ request continued his story. "Last week I had occasion to go to the stable immediately behind the house and on one of the walls saw in figures made with a piece of white chalk, this sign," and drawing his fountain pen from his pocket, he marked on our white table cloth 2 2 . — 4 . "I haven’t been able to sleep since, and now I have come to you for help." "Why did you visit the stable, Mr. Drake?" asked Keys. "Well, lately the carriage and harness have not been properly cleaned, or the horse well groomed, and I went to speak to the stable-man about it." Hastily consulting a time-table, Keys disappeared into his bed room, returning the next moment disguised as a stable-boy, even to a straw, which he was chewing assiduously. "Whenson will put you up, Mr. Drake, and I will report to you at breakfast tomorrow morning. Meanwhile you can sleep in peace." Coming down to breakfast the next morning, we found Keys seated by the fire reading the paper. "Good morning, all is well, but breakfast first and business afterwards," he said. It was not until our pipes were well alight that Keys deigned to satisfy our curiosity. "The mystery was a very harmless one, Mr. Drake, as I expected it would be after the clue you gave me. I went round to the back of your house and looked in at the stable window, and there was the culprit, your young stable-man, with a laudable desire to improve his mind, though rather at the expense of his duty to you, I am afraid, was pouring over the arithmetic section of Barmsbirth’s Universal Educator, and with a piece of white chalk was endeavoring to work out a simple sum on your stable wall, and, my dear sir, the answer to his sum, and the explanation of your mystery, is that two and two make four." *IV.* *THE ADVENTURE OF THEOPHILUS BROWN* "’Tis not in mortals to command success," as the Immortal Bard hath it, and to illustrate the fact that my friend, Mr. Surelock Keys, really is mortal which one might easily doubt from some of the marvellous things that he has done, I will give you an incident that happened recently. A tremendous battering at my bedroom door woke me from a sound sleep, and an urgent request from Keys, to join him downstairs, hurried me into my clothes. On entering the dining room I saw a pallid youth whom Keys introduced as Mr. Theophilus Brown. Then Keys, in his most abrupt manner, asked him what he wished to tell us, and after much hesitation, and with frightened glances towards the door, he blurted out a very incoherent and rambling story about a severed leg, that he had seen hanging up somewhere, on his way home the previous evening, and how he was afraid something dreadful would happen to him because he didn’t tell the police.