The setting mechanism on the 1873 Model is the same as the 1872 Model. In both cases, the early examples had a variety of setting mechanisms and eventually settled on the rocking lever. The rocking lever is distinct from the others, but the button, nail set and Fitch's patent setting are all essentially the same. The nail setting and Fitch's setting have an elongated lever and are identical except that the Fitch's mechanism has a latching spring mounted in the case that is unlocked by depressing a small pin when the cover is closed. The button set, as seen here, has an abbreviated lever that is pushed in by a button mounted in the body of the case. It is not clear how the button reaches the push piece and I have not been able to examine a case with the mechanism to see.