The Boreal Arrow 

Code BA10032930: Open Face Swiss Muller and Vaucher Compass c. 1920

This is a nice Swiss open face compass dating c. 1920 made by Muller & Vaucher. The case is made of Aluminium and is in excellent condition. It has a rotating bezel to do angles calculations. It has a 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 SM & V (Muller  & Vaucher) S. A. Bienne & Genรจve and Swiss PATENT 1916. On the back of the compass, there is another Swiss patent number, which I think is for the case: 71481. The compass is very precise and points North easily. It measures 42mm in diameter.