The Freemason's Secret Handshake

Watson attempts to use Sherlock Holmes' method to try to draw conclusions about the man, but he can't. As far as he can tell, this guy is just a very average British tradesman. And what Holmes notices that Watson is trying to work things out, and he finds it amusing. Then Holmes explains the things that he's observed. Snuff is basically a powdered form of tobacco that people used to take. I guess it was fairly common in those days. So he done manual labor, like physical work. He takes snuff. A Freemason is a kind of secret society still going today.