t hospital the words 'Charing Cross' very naturally suggest
themselves."

"You may be right."

"The probability lies in that direction. And if we take this as a
working hypothesis we have a fresh basis from which to start our
construction of this unknown visitor."

"Well, then, supposing that 'C.C.H.' does stand for 'Charing Cross
Hospital,' what further inferences may we draw?"

"Do none suggest themselves? You know my methods. Apply them!"

"I can only think of the obvious conclusion that the man has practised
in town before going to the country."

"I think that we might venture a little farther than this. Look at it
in this light. On what occasion would it be most probable that such a
presentation would be made? When would his friends unite to give him
a pledge of their good will? Obviously at the moment when Dr. Mortimer
withdrew from the service of the hospital in order to start a practice
for himself. We know there has been a presentation. We believe there has
been a change from a town hospital to a country practice. Is it, then,
stretching our inference too far to say that the presentation was on the
occasion of the change?"

"It certainly seems probable."

"Now, you will observe that he could not have been on the staff of the
hospital, since only a man well-established in a London practice could
hold such a position, and such a one would not drift into the country.
What was he, then? If he was in the hospital and yet not on the staff he
could only have been a house-surgeon or a house-physician--little more
than a senior student. And he left five years ago--the date is on the
stick. So your grave, middle-aged family practitioner vanishes into
thin air, my dear Watson, and there emerges a young fellow under thirty,
amiable, unambitious, absent-minded, and the possessor of a favourite
dog, which I should describe roughly as being larger than a terrier and
smaller than a mastiff."

I laughed incredulously as Sherlock Holmes leaned back in his settee and
blew little wavering rings of smoke up to the ceiling.

"As to the latter part, I have no means of checking you," said I, "but
at least it is not difficult to find out a few particulars about the
man's age and professional career." From my small medical shelf I took
down the Medical Directory and turned up the name. There were several
Mortimers, but only one who could be our visitor. I read his record
aloud.

"Mortimer, James, M.R.C.S., 1882, Gr