See how the folk swarm over yonder in the gaslight."
"They are coming from work in the yard."
"Dirty-looking rascals, but I suppose every one has some little immortal spark concealed about him. You would not think it, to look at them. There is no a priori probability about it. A strange enigma is man!"
"Some one calls him a soul concealed in an animal," I suggested.
"Winwood Reade is good upon the subject," said Holmes. "He remarks that, while the individual man is an insoluble puzzle, in the aggregate he becomes a mathematical certainty. You can, for example, never foretell what any one man will do, but you can say with precision what an average number will be up to. Individuals vary, but percentages remain constant. So says the statistician. But do I see a handkerchief? Surely there is a white flutter over yonder."
"Yes, it is your boy," I cried. "I can see him plainly."
"And there is the Aurora," exclaimed Holmes, "and going like the devil! Full speed ahead, engineer. Make after that launch with the yellow light. By heaven, I shall never forgive myself if she proves to have the heels of us!"
She had slipped unseen through the yard-entrance and passed behind two or three small craft, so that she had fairly got her speed up before we saw her. Now she was flying down the stream, near in to the shore, going at a tremendous rate. Jones looked gravely at her and shook his head.
"She is very fast," he said. "I doubt if we shall catch her."
"We MUST catch her!" cried Holmes, between his teeth. "Heap it on, stokers! Make her do all she can! If we burn the boat we must have them!"
We were fairly after her now. The furnaces roared, and the powerful engines whizzed and clanked, like a great metallic heart. Her sharp, steep prow cut through the river-water and sent two rolling waves to right and to left of us. With every throb of the engines we sprang and quivered like a living thing. One great yellow lantern in our bows threw a long, flickering funnel of light in front of us. Right ahead a dark blur upon the water showed where the Aurora lay, and the swirl of white foam behind her spoke of the pace at which she was going. We flashed past barges, steamers, merchant-vessels, in and out, behind this one and round the other. Voices hailed us out of the darkness, but still the Aurora thundered on, and still we followed close upon her track.
"Pile it on, men, pile it on!" cried Holmes, looking down into the engine-room, while the fierce glow from below beat upon his eager, aquiline face. "Get every pound of steam you can."
"I think we gain a little," said Jones, with his eyes on the Aurora.
"I am sure of it," said I. "We shall be up with her in a very few minutes."
At that moment, however, as our evil fate would have it, a tug with three barges in tow blundered in between us. It was only by putting our helm hard down that we avoided a collision, and before we could round them and recover our way the Aurora had gained a good two hundred yards. She was still, however, well in view, and the murky uncertain twilight was setting into a clear starlit night. Our boilers were strained to their utmost, and the frail shell vibrated and creaked with the fierce energy which was driving us along. We had shot through the Pool, past the West India Docks, down the long Deptford Reach, and up again after rounding the Isle of Dogs. The dull blur in front of us resolved itself now clearly enough into the dainty Aurora. Jones turned our search-light upon her, so that we could plainly see the figures upon her deck. One man sat by the stern, with something black between his knees over which he stooped. Beside him lay a dark mass which looked like a Newfoundland dog. The boy held the tiller, while against the red glare of the furnace I could see old Smith, stripped to the waist, and shovelling coals for dear life. They may have had some doubt at first as to whether we were really pursuing them, but now as we followed every winding and turning which they took there could no longer be any question about it.