"Deduce what?" said he, petulantly.

"Why, that he was a retired sergeant of Marines."

"I have no time for trifles," he answered, brusquely;
then with a smile, "Excuse my rudeness. You broke the thread
of my thoughts; but perhaps it is as well. So you actually were
not able to see that that man was a sergeant of Marines?"

"No, indeed."

"It was easier to know it than to explain why I knew it.
If you were asked to prove that two and two made four, you might
find some difficulty, and yet you are quite sure of the fact.
Even across the street I could see a great blue anchor
tattooed on the back of the fellow's hand. That smacked of
the sea. He had a military carriage, however, and regulation
side whiskers. There we have the marine. He was a man with
some amount of self-importance and a certain air of command.
You must have observed the way in which he held his head and
swung his cane. A steady, respectable, middle-aged man, too,
on the face of him -- all facts which led me to believe that
he had been a sergeant."

"Wonderful!" I ejaculated.

"Commonplace," said Holmes, though I thought from his
expression that he was pleased at my evident surprise and
admiration. "I said just now that there were no criminals.