We turned down a narrow lane and passed through a small side-door. Then we ascended the bleak stone staircase. Near the further end a passage led to the chemical laboratory.

      This was a lofty chamber with countless bottles. Broad, low tables were scattered about. There was only one man in the room, who was bending over a table. He was absorbed in his work. Suddenly he sprang to his feet with a cry of pleasure.

      “Great!” he shouted to my companion. “Look! It is a re-agent which is precipitated by hemoglobin[4], and by nothing else.”

      “Dr. Watson, Mr. Sherlock Holmes,” said Stamford.

      “How are you?” he said cordially. “You visited Afghanistan, I see.”

      “How did you know that?” I asked in astonishment.

      “Never mind,” said he, chuckling to himself. “The question now is about hemoglobin. Do you see the significance of this discovery?”

      “It is interesting, no doubt,” I answered, “but practically…”

      “It is the most practical discovery for years. It gives us an infallible test for blood stains. Come over here now!” He drew me over to the table. “Let us have some fresh blood,” he said. He dug a long bodkin into his finger, and drew off the drop of blood in a chemical pipette. “Now, I add this small quantity of blood to water. You perceive that the mixture has the appearance of pure water. The proportion of blood is one in a million. However, we shall be able to obtain the characteristic reaction.”

      He threw into the vessel a few white crystals, and then added some drops of a transparent fluid. In an instant the contents changed its colour.

      “Ha! ha!” he cried. He was as delighted as a child with a new toy. “What do you think of that? It acts as well whether the blood is old or new. Hundreds of criminals will pay the penalty of their crimes.”

      “Indeed!” I murmured.

      “For example, we see brownish stains upon the criminal’s clothes. Are they blood stains, or mud stains, or rust stains, or fruit stains, or what are they? That is a question which puzzles many experts, and why? Because there was no reliable test. Now we have the Sherlock Holmes’ test!”

      His eyes glittered as he spoke, and he put his hand over his heart and bowed.

      “Congratulations,” I remarked. I was surprised at his enthusiasm.

      “I can name many cases in which this test will be decisive.”

      “We came here on business[5],” said Stamford. He sat down on a high three-legged stool, and pushed another one in my direction with his foot. “My friend is looking for a room, and you were complaining that you could get no one to share expenses with you. So, I bring you together.”

      Sherlock Holmes seemed delighted.

      “I know a good suite in Baker Street,” he said. “You don’t mind the smell of strong tobacco, I hope?”

      “I smoke myself,” I answered.

      “That’s good. I have chemicals, and occasionally do experiments. Will that annoy you?”

      “By no means.”

      “Moreover, at times I don’t open my mouth for days. You must not think I am sulky when I do that. And what about you? It’s better for two fellows to know one another before they begin to live together.”

      I laughed.

      “I have a bull pup[6],” I said, “I hate noise, and I am extremely lazy. I have other vices, but those are the principal ones.”

      “Is the violin-playing some noise for you?” he asked, anxiously.

      “It depends on the player,” I answered.

      “Oh, that’s all right,” he cried, with a merry laugh. “I think we may begin to live together, if the rooms are agreeable to you.”

      “When shall we see them?”

      “Come to me at noon tomorrow, and we’ll go there together,” he answered.

      “All right – noon exactly,” said I.

      We left him working among his chemicals, and we walked together towards my hotel.

      “By the way,” I asked suddenly, “how did he know that I had come from Afghanistan?”

      My companion smiled.

      “That’s his little peculiarity,” he said.

      “Oh! a mystery?” I cried. “This is very piquant.”

      Stamford bade me good-bye.

      “I think he knows more about you than you about him. Good-bye.”

      “Good-bye,” I answered, and strolled on to my hotel.

      Chapter II

      The Science of Deduction

      We met next day and inspected the rooms at No. 221B, Baker Street. They consisted of a couple of comfortable bed-rooms and a single large sitting-room, with two broad windows. The apartments were desirable in every way. That evening I moved my things from the hotel, and on the following morning Sherlock Holmes followed me with several boxes and portmanteaus.

      Holmes was certainly not a difficult man to live with. He was quiet, and his habits were regular. He breakfasted and went out early in the morning. Sometimes he spent his day at the chemical laboratory, sometimes in the dissecting-rooms[7], and occasionally in long walks. Sometimes he was lying upon the sofa in the sitting-room, and he was not uttering a word or moving a muscle from morning to night.

      As the weeks went by, my interest in him gradually deepened and increased. In height he was rather over six feet, and excessively lean. His eyes were sharp and piercing; and his hawk-like nose was very thin. His chin marked the man of determination.

      His ignorance was as remarkable as his knowledge. Of contemporary literature, philosophy and politics he knew nothing. And my surprise reached a climax, when I found incidentally that he was ignorant of the Copernican Theory and of the composition of the Solar System.

      “You will be astonished,” he said, smiling. “Now that I do know it I shall do my best to forget it.”

      “To forget it!”

      “You see,” he explained, “a man’s brain is like a little empty attic. A fool