Description and Notes:
This Original Lotter compact set was made by Nobema, or the other way around, I am not sure. Anyway, the name of both companies were stamped on the instrument (the ruling pen shown in the above picture is a later replacement, the original one was missing upon acquisition). According to a page that I've found earlier on the web, which now is gone, the Nobema Products Corporation was established in 1901, but was bought by the founder of the Riebe's Artists' Materials in the 1930s.
In addition to the common feature of other similar compasses, the turnabout compass in this set is unique in that it has a built-in extension bar in the right arm and a simple self-centering mechanism, as the two arms are geared in the main joint so that the handle will remain vertical regardless of the opening angles of the arms.