These brass U.S. Engineer Corps compasses were manufactured by at least 2 companies: Cruchon & Emons London and Plan, Ltd. Neuchatel Switzerland.
They represent an early (circa WWI) attempt at a mirror compass, with an (originally) polished brass insert in the cover which allows the card (w/ bearings printed in reverse) to be read while sighting on a target.
The bottom of the case is stamped with Plan Ltd. Neuchatel Switzerland and an individual serial number.(3455) The top of the case is marked US Engineer Corps.
The compass is in a perfect condition, like new.
Contains Radium paint. (0.5 micro sievert/h)