“I will now cut one of these pills in two,” said Holmes, and drawing his penknife he suited the action to the word. “One half we return into the box for future purposes. The other half I will place in this wineglass, in which is a teaspoonful of water. You perceive that our friend, the doctor, is right, and that it readily dissolves.”

“This may be very interesting,” said Lestrade, in the injured tone of one who suspects that he is being laughed at; “I cannot see, however, what it has to do with the death of Mr. Joseph Stangerson.”

“Patience, my friend, patience! You will find in time that it has everything to do with it. I shall now add a little milk to make the mixture palatable, and on presenting it to the dog we find that he laps it up readily enough.”

As he spoke he turned the contents of the wineglass into a saucer and placed it in front of the terrier, who speedily licked it dry. Sherlock Holmes’s earnest demeanour had so far convinced us that we all sat in silence, watching the animal intently, and expecting some startling effect. None such appeared, however. The dog continued to lie stretched upon the cushion, breathing in a laboured way, but apparently neither the better nor the worse for its draught.

Holmes had taken out his watch, and as minute followed minute without result, an expression of the utmost chagrin and disappointment appeared upon his features. He gnawed his lip, drummed his fingers upon the table, and showed every other symptom of acute impatience. So great was his emotion that I felt sincerely sorry for him, while the two detectives smiled derisively, by no means displeased at this check which he had met.

“It can’t be a coincidence,” he cried, at last springing from his chair and pacing wildly up and down the room; “it is impossible that it should be, a mere coincidence. The very pills which I suspected in the case of Drebber are actually found after the death of Stangerson. And yet they are inert. What can it mean? Surely my whole chain of reasoning cannot have been false. It is impossible! And yet this wretched dog is none the worse. Ah, I have it! I have it!” With a perfect shriek of delight he rushed to the box, cut the other pill in two, dissolved it, added milk, and presented it to the terrier. The unfortunate creature’s tongue seemed hardly to have been moistened in it before it gave a convulsive shiver in every limb, and lay as rigid and lifeless as if it had been struck by lightning.

Sherlock Holmes drew a long breath, and wiped the perspiration from his forehead. “I should have more faith,” he said; “I ought to know by this time that when a fact appears to be opposed to a long train of deductions, it invariably proves to be capable of bearing some other interpretation. Of the two pills in that box, one was of the most deadly poison, and the other was entirely harmless. I ought to have known that before ever I saw the box at all.”

This last statement appeared to me to be so startling that I could hardly believe that he was in his sober senses. There was the dead dog, however, to prove that his conjecture had been correct. It seemed to me that the mists in my own mind were gradually clearing away, and I began to have a dim, vague perception of the truth.

“All this seems strange to you,” continued Holmes, “because you failed at the beginning of the inquiry to grasp the importance of the single real clue which was presented to you. I had the good fortune to seize upon that, and everything which has occurred since then has served to confirm my original supposition, and, indeed, was the logical sequence of it. Hence things which have perplexed you and made the case more obscure have served to enlighten me and to strengthen my conclusions. It is a mistake to confound strangeness with mystery. The most commonplace crime is often the most mysterious, because it presents no new or special features from which deductions may be drawn. This murder would have been infinitely more difficult to unravel had the body of the victim been simply found lying in the roadway without any of those outre and sensational accompaniments which have rendered it remarkable. These strange details, far from making the case more difficult, have really had the effect of making it less so.”

Mr. Gregson, who had listened to this address with considerable impatience, could contain himself no longer. “Look here, Mr. Sherlock Holmes,” he said, “we are all ready to acknowledge that you are a smart man, and that you have your own methods of working. We want something more than mere theory and preaching now, though. It is a case of taking the man. I have made my case out, and it seems I was wrong. Young Charpentier could not have been engaged in this second affair. Lestrade went after his man, Stangerson, and it appears that he was wrong too. You have thrown out hints here, and hints there, and seem to know more than we do, but the time has come when we feel that we have a right to ask you straight how much you do know of the business. Can you name the man who did it?”

“I cannot help feeling that Gregson is right, sir,” remarked Lestrade. “We have both tried, and we have both failed. You have remarked more than once since I have been in the room that you had all the evidence which you require. Surely you will not withhold it any longer.”

“Any delay in arresting the assassin,” I observed, “might give him time to perpetrate some fresh atrocity.”

Thus pressed by us all, Holmes showed signs of irresolution. He continued to walk up and down the room with his head sunk on his chest and his brows drawn down, as was his habit when lost in thought.

“There will be no more murders,” he said at last, stopping abruptly and facing us. “You can put that consideration out of the question. You have asked me if I know the name of the assassin. I do. The mere knowing of his name is a small thing, however, compared with the power of laying our hands upon him. This I expect very shortly to do. I have good hopes of managing it through my own arrangements; but it is a thing which needs delicate handling, for we have a shrewd and desperate man to deal with, who is supported, as I have had occasion to prove, by another who is as clever as himself. As long as this man has no idea that anyone can have a clue there is some chance of securing himbut if he had the slightest suspicion, he would change his name, and vanish in an instant among the four million inhabitants of this great city. Without meaning to hurt either of your feelings, I am bound to say that T consider these men to be more than a match for the official force, and that is why I have not asked your assistance. If I fail, I shall, of course, incur all the blame due to this omission; but that I am prepared for. At present I am ready to promise that the instant that I can communicate with you without endangering my own combinations, I shall do so.”

Gregson and Lestrade seemed to be far from satisfied by this assurance, or by the depreciating allusion to the detective police. The former had flushed up to the roots of his flaxen hair, while the other’s beady eyes glistened with curiosity and resentment. Neither of them had time to speak, however, before there was a tap at the door, and the spokesman of the street Arabs, young Wiggins, introduced his insignificant and unsavoury person.

“Please, sir,” he said, touching his forelock, “I have the cab downstairs.”

“Good boy,” said Holmes, blandly. “Why don’t you introduce this pattern at Scotland Yard?” he continued, taking a pair of steel handcuffs from a drawer. “See how beautifully the spring works. They fasten in an instant.”

“The old pattern is good enough,” remarked Lestrade, “if we can only find the man to put them on.”

“Very good, very good,” said Holmes, smiling. “The cabman may as well help me with my boxes. Just ask him to step up, Wiggins.”

I was surprised to find my companion speaking as though he were about to set out on a journey, since he had not said anything to me about it. There was a small portmanteau in the room, and this he pulled out and began to strap. He was busily engaged at it when the cabman entered the room.