“You mean the retired sergeant of Marines,” said Sherlock Holmes.

“Brag and bounce!” thought I to myself. “He knows that I cannot verify his guess.”

The thought had hardly passed through my mind when the man whom we were watching caught sight of the number on our door, and ran rapidly across the roadway. We heard a loud knock, a deep voice below, and heavy steps ascending the stair.

“For Mr. Sherlock Holmes,” he said, stepping into the room and handing my friend the letter.

Here was an opportunity of taking the conceit out of him. He little thought of this when he made that random shot. “May I ask, my lad,” I said, in the blandest voice, “what your trade may be?”

“Commissionaire, sir,” he said, gruffly. “Uniform away for repairs.”

“And you were?” I asked, with a slightly malicious glance at my companion.

“A sergeant, sir, Royal Marine Light Infantry, sir. No answer? Right, sir.”

He clicked his heels together, raised his hand in salute, and was gone.

Chapter 3.

The Lauriston Garden Mystery

I confess that I was considerably startled by this fresh proof of the practical nature of my companion’s theories. My respect for his powers of analysis increased wondrously. There still remained some lurking suspicion in my mind, however, that the whole thing was a prearranged episode, intended to dazzle me, though what earthly object he could have in taking me in was past my comprehension. When I looked at him, he had finished reading the note, and his eyes had assumed the vacant, lacklustre expression which showed mental abstraction.

“How in the world did you deduce that?” I asked.

“Deduce what?” said he, petulantly.

“Why, that he was a retired sergeant of Marines.”

“I have no time for trifles,” he answered, brusquely, then with a smile, “Excuse my rudeness. You broke the thread of my thoughts; but perhaps it is as well. So you actually were not able to see that that man was a sergeant of Marines?”