The Boreal Arrow 

Code BA11050117: Open Face Swiss Compass c. 1920

This is a nice Swiss open face compass dating c. 1920. It is very similar to the model made by Muller & Vaucher. The case is made of brass and is in excellent condition. It has a rotating bezel to do angles calculations. It hasa push-pull button to activate/deactivate the transit lock that freezes the needle when the compass is not in use. Glass crystal and dial are in excellent condition.  The dial is marked SWISS MADE and BREVETE DEM (which I think means in French that the patent (BREVET) has been requested (DEM = DEMANDE) and is waiting for approval). This is why I think it is a Muller & Vaucher but the maker did not put name on the compass before the patent was approved. The compass is very precise and points North easily. It measures 42mm in diameter.