He flicked the horse with his whip, and we dashed away through the endless succession of sombre and deserted streets, which widened gradually, until we were flying across a broad balustraded bridge, with the murky river flowing sluggishly beneath us. Beyond lay another dull wilderness of bricks and mortar, its silence broken only by the heavy, regular footfall of the policeman, or the songs and shouts of some belated party of revellers. A dull wrack was drifting slowly across the sky, and a star or two twinkled dimly here and there through the rifts of the clouds. Holmes drove in silence, with his head sunk upon his breast, and the air of a man who is lost in thought, while I sat beside him, curious to learn what this new quest might be which seemed to tax his powers so sorely, and yet afraid to break in upon the current of his thoughts. We had driven several miles, and were beginning to get to the fringe of the belt of suburban villas, when he shook himself, shrugged his shoulders, and lit up his pipe with the air of a man who has satisfied himself that he is acting for the best.