I took it up and glanced at it. “Mr. Victor Hatherley, hydraulic engineer, 16A, Victoria Street (3d floor).” That was the name, style, and abode of my morning visitor. “I regret that I have kept you waiting,” said I, sitting down in my library-chair. “You are fresh from a night journey, I understand, which is in itself a monotonous occupation.”

“Oh, my night could not be called monotonous,” said he, and laughed. He laughed very heartily, with a high, ringing note, leaning back in his chair and shaking his sides. All my medical instincts rose up against that laugh.

“Stop it!” I cried; “pull yourself together!” and I poured out some water from a carafe.

It was useless, however. He was off in one of those hysterical outbursts which come upon a strong nature when some great crisis is over and gone. Presently he came to himself once more, very weary and pale-looking.

“I have been making a fool of myself,” he gasped.

“Not at all. Drink this.” I dashed some brandy into the water, and the colour began to come back to his bloodless cheeks.

“That’s better!” said he. “And now, Doctor, perhaps you would kindly attend to my thumb, or rather to the place where my thumb used to be.”

He unwound the handkerchief and held out his hand. It gave even my hardened nerves a shudder to look at it. There were four protruding fingers and a horrid red, spongy surface where the thumb should have been. It had been hacked or torn right out from the roots.

“Good heavens!” I cried, “this is a terrible injury. It must have bled considerably.”

“Yes, it did. I fainted when it was done, and I think that I must have been senseless for a long time. When I came to I found that it was still bleeding, so I tied one end of my handkerchief very tightly round the wrist and braced it up with a twig.”

“Excellent! You should have been a surgeon.”

“It is a question of hydraulics, you see, and came within my own province.”

“This has been done,” said I, examining the wound, “by a very heavy and sharp instrument.”

“A thing like a cleaver,” said he.

“An accident, I presume?”

“By no means.”

“What! a murderous attack?”

“Very murderous indeed.”

“You horrify me.”

I sponged the wound, cleaned it, dressed it, and finally covered it over with cotton wadding and carbolized bandages. He lay back without wincing, though he bit his lip from time to time.

“How is that?” I asked when I had finished.

“Capital! Between your brandy and your bandage, I feel a new man. I was very weak, but I have had a good deal to go through.”

“Perhaps you had better not speak of the matter. It is evidently trying to your nerves.”

“Oh, no, not now. I shall have to tell my tale to the police; but, between ourselves, if it were not for the convincing evidence of this wound of mine, I should be surprised if they believed my statement; for it is a very extraordinary one, and I have not much in the way of proof with which to back it up; and, even if they believe me, the clues which I can give them are so vague that it is a question whether justice will be done.”

“Ha!” cried I, “if it is anything in the nature of a problem which you desire to see solved, I should strongly recommend you to come to my friend, Mr. Sherlock Holmes, before you go to the official police.”

“Oh, I have heard of that fellow,” answered my visitor, “and I should be very glad if he would take the matter up, though of course I must use the official police as well. Would you give me an introduction to him?”

“I’ll do better. I’ll take you round to him myself.”

“I should be immensely obliged to you.”