Nice find! I'd bet 1920s or 30s from the style of the face. It looks to be in really nice shape
The outer case is an aftermarket piece which was a pretty common way for the working man to protect his watch while on the job. Companies which had to provide watches for the workers often used these cases to protect their investments, which would explain the little number stamped on the case. From the black colour on the watch itself it could be a silver case, well tarnished or a gun metal case with a lot of the finish worn off. You'll have to post pictures of the inside of the case as well as the movement. These old pieces aren't worth much, maybe $300 in good running order, but still make really good reliable timepieces once serviced.