The directions on the rose of the compass below are in French (N-NE-E-SE-S-SO-O-NO). Between NO and N, there’s a tiny arrow. Note that the compass rose is of paper/cardboard. The tapered shape of the compass black enamelled brass outer case looks like a button, so there might have been a cover, hiding the compass from view, and a loop to attach it to a coat, but both are missing. When I poked into the hole at the bottom, the compass itself came loose, revealing a more ‘classical’ type escape compass. It looks as though the compass was made to exactly fit the outer case. The size of the compass itself, including its inner case, is about the same as most other round compasses at 0.665″ (16,9 mm) wide x 0.213″ (5,4 mm) high. The compass with the outer case is 0.472″ (12 mm) high x 0.839″ (21,3 mm) wide. The compass needle pivots on a brass pin, pressed into the bottom of the case. This can be seen at the back, where there’s a small hole at the center. The needle is made of steel and the side pointing North is blued. The glass cover has a bevelled edge, similar to the later pill box type compasses which were also used for hiding into uniform buttons.
I haven’t been able to determine the origin of this compass and I can’t be sure the outer case is part of a uniform button, so if someone has any literature on this one, please let me know.
Also see my article on escape compasses: