and
better means of explaining the crime. I was turning over these two
alternatives, not unobserved by my watchful colleague, when Polton
entered the room; a broad grin was on his face, and a drawing-board,
that he carried like a tray, bore twenty-four neatly turned boxwood
pieces.

Thorndyke at once entered into the unspoken jest that beamed from the
countenance of his subordinate.

"Here is Polton with a problem for you, Jervis," he said. "He assumes
that I have invented a new parlour game, and has been trying to work out
the moves. Have you succeeded yet, Polton?"

"No, sir, I haven't; but I suspect that one of the players will be a man
in a wig and gown."

"Perhaps you are right," said Thorndyke; "but that doesn't take you very
far. Let us hear what Dr. Jervis has to say."

"I can make nothing of them," I answered. "Polton showed me the drawing
this morning, and then was terrified lest he had committed a breach of
confidence, and I have been trying ever since, without a glimmer of
success, to guess what they can be for."

"H'm," grunted Thorndyke, as he sauntered up and down the room, teacup
in hand, "to guess, eh? I like not that word 'guess' in the mouth of a
man of science. What do you mean by a 'guess'?"

His manner was wholly facetious, but I professed to take his question
seriously, and replied--

"By a guess, I mean a conclusion arrived at without data."

"Impossible!" he exclaimed, with mock sternness. "Nobody but an utter
fool arrives at a conclusion without data."

"Then I must revise my definition instantly," I rejoined. "Let us say
that a guess is a conclusion drawn from insufficient facts."

"That is better," said he; "but perhaps it would be better still to say
that a guess is a particular and definite conclusion deduced from facts
which properly yield only a general and indefinite one. Let us take an
instance," he continued. "Looking out of the window, I see a man walking
round Paper Buildings. Now suppose I say, after the fashion of the
inspired detective of the romances, 'That man is a stationmaster or
inspector,' that would be a guess. The observed facts do not yield the
conclusion, though they do warrant a conclusion less definite and more
general."

"You'd have been right though, sir!" exclaimed Polton, who had stepped
forward with me to examine the unconscious subject of the demonstration.
"That gent used to be the stationmaster at Camberwell. I remember him
well." The little ma