irs and a bromide enlargement
too, which will be mounted and dried by the time you have finished your
breakfast."

"A wonderful man that, Jervis," my friend observed as his assistant
retired. "Looks like a rural dean or a chancery judge, and was obviously
intended by Nature to be a professor of physics. As an actual fact he
was first a watchmaker, then a maker of optical instruments, and now he
is mechanical factotum to a medical jurist. He is my right-hand, is
Polton; takes an idea before you have time to utter it--but you will
make his more intimate acquaintance by-and-by."

"Where did you pick him up?" I asked.

"He was an in-patient at the hospital when I first met him, miserably
ill and broken, a victim of poverty and undeserved misfortune. I gave
him one or two little jobs, and when I found what class of man he was I
took him permanently into my service. He is perfectly devoted to me, and
his gratitude is as boundless as it is uncalled for."

"What are the photographs he was referring to?" I asked.

"He is making an enlarged _facsimile_ of one of the thumb-prints on
bromide paper and a negative of the same size in case we want the print
repeated."

"You evidently have some expectation of being able to help poor Hornby,"
said I, "though I cannot imagine how you propose to go to work. To me
his case seems as hopeless a one as it is possible to conceive. One
doesn't like to condemn him, but yet his innocence seems almost
unthinkable."

"It does certainly look like a hopeless case," Thorndyke agreed, "and I
see no way out of it at present. But I make it a rule, in all cases, to
proceed on the strictly classical lines of inductive inquiry--collect
facts, make hypotheses, test them and seek for verification. And I
always endeavour to keep a perfectly open mind.

"Now, in the present case, assuming, as we must, that the robbery has
actually taken place, there are four conceivable hypotheses: (1) that
the robbery was committed by Reuben Hornby; (2) that it was committed by
Walter Hornby; (3) that it was committed by John Hornby, or (4) that it
was committed by some other person or persons.

"The last hypothesis I propose to disregard for the present and confine
myself to the examination of the other three."

"You don't think it possible that Mr. Hornby could have stolen the
diamonds out of his own safe?" I exclaimed.

"I incline at present to no one theory of the matter," replied
Thorndyke. "I merely state t