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, Grimpen, Dartmoor, Devon.