oo, I'll say that. You
had better come into Mr. Singleton's office," and he conducted us along
a corridor and into a large, barely-furnished room, where we found a
sedate-looking gentleman seated at a large writing table.

"How-d'ye-do, doctor?" said the latter, rising and holding out his hand.
"I can guess what you've come for. Want to see that thumb-print, eh?"

"Quite right," answered Thorndyke, and then, having introduced me, he
continued: "We were partners in the last game, but we are on opposite
sides of the board this time."

"Yes," agreed Mr. Singleton; "and we are going to give you check-mate."

He unlocked a drawer and drew forth a small portfolio, from which he
extracted a piece of paper which he laid on the table. It appeared to be
a sheet torn from a perforated memorandum block, and bore the pencilled
inscription: "Handed in by Reuben at 7.3 p.m., 9.3.01. J. H." At one end
was a dark, glossy blood-stain, made by the falling of a good-sized
drop, and this was smeared slightly, apparently by a finger or thumb
having been pressed on it. Near to it were two or three smaller smears
and a remarkably distinct and clean print of a thumb.

Thorndyke gazed intently at the paper for a minute or two, scrutinising
the thumb-print and the smears in turn, but making no remark, while Mr.
Singleton watched his impassive face with expectant curiosity.

"Not much difficulty in identifying that mark," the official at length
observed.

"No," agreed Thorndyke; "it is an excellent impression and a very
distinctive pattern, even without the scar."

"Yes," rejoined Mr. Singleton; "the scar makes it absolutely conclusive.
You have a print with you, I suppose?"

"Yes," replied Thorndyke, and he drew from a wide flap-pocket the
enlarged photograph, at the sight of which Mr. Singleton's face
broadened into a smile.

"You don't want to put on spectacles to look at that," he remarked; "not
that you gain anything by so much enlargement; three diameters is ample
for studying the ridge-patterns. I see you have divided it up into
numbered squares--not a bad plan; but ours--or rather Galton's, for we
borrowed the method from him--is better for this purpose."

He drew from the portfolio a half-plate photograph of the thumb-print
which appeared magnified to about four inches in length. The print was
marked by a number of figures written minutely with a fine-pointed pen,
each figure being placed on an "island," a loop, a bifurcation