One of the most remarkable characteristics of Sherlock Holmes was his power of throwing his brain out of action and switching all his thoughts on to lighter things whenever he had convinced himself that he could no longer work to advantage. I remember that during the whole of that memorable day he lost himself in a monograph which he had undertaken upon the Polyphonic Motets of Lassus. For my own part I had none of this power of detachment, and the day, in consequence, appeared to be interminable. The great national importance of the issue, the suspense in high quarters, the direct nature of the experiment which we were trying--all combined to work upon my nerve. It was a relief to me when at last, after a light dinner, we set out upon our expedition. Lestrade and Mycroft met us by appointment at the outside of Gloucester Road Station. The area door of Oberstein's house had been left open the night before, and it was necessary for me, as Mycroft Holmes absolutely and indignantly declined to climb the railings, to pass in and open the hall door. By nine o'clock we were all seated in the study, waiting patently for our man.
An hour passed and yet another. When eleven struck, the measured beat of the great church clock seemed to sound the dirge of our hopes. Lestrade and Mycroft were fidgeting in their seats and looking twice a minute at their watches. Holmes sat silent and composed, his eyelids half shut, but every sense on the alert. He raised his head with a sudden jerk.
"He is coming," said he.
There had been a furtive step past the door. Now it returned. We heard a shuffling sound outside, and then two sharp taps with the knocker. Holmes rose, motioning us to remain seated. The gas in the hall was a mere point of light. He opened the outer door, and then as a dark figure slipped past him he closed and fastened it. "This way!" we heard him say, and a moment later our man stood before us. Holmes had followed him closely, and as the man turned with a cry of surprise and alarm he caught him by the collar and threw him back into the room. Before our prisoner had recovered his balance the door was shut and Holmes standing with his back against it. The man glared round him, staggered, and fell senseless upon the floor. With the shock, his broad-brimmed hat flew from his head, his cravat slipped sown from his lips, and there were the long light beard and the soft, handsome delicate features of Colonel Valentine Walter.
Holmes gave a whistle of surprise.
"You can write me down an ass this time, Watson," said he. "This was not the bird that I was looking for."
"Who is he?" asked Mycroft eagerly.
"The younger brother of the late Sir James Walter, the head of the Submarine Department. Yes, yes; I see the fall of the cards. He is coming to. I think that you had best leave his examination to me."
We had carried the prostrate body to the sofa. Now our prisoner sat up, looked round him with a horror-stricken face, and passed his hand over his forehead, like one who cannot believe his own senses.
"What is this?" he asked. "I came here to visit Mr. Oberstein."