This compass has a brass bowl gimbal mounted in a wooden box. The compass
itself may date from the mid-1860s. The graduated ring is curved. The needle
float is in the form of crossed cylinders, as described in the patent (#38,125)
granted to Ritchie on April 7, 1863.
The gimbal ring, which seems to be of a somewhat later date than the compass,
identifies several Ritchie patents in addition to that of 1863. The patent of
May 12, 1868 (#77,763) describes a paint that would not deteriorate in the liquid
in the compass. The patent of July 19, 1870 (#105,492) describes a way to hold
the glass in place with a water-tight joint. And the patent of November 14, 1876
(#184,300) describes a "fascicular magnet" composed of a series of
separate drawn wires of steel laid parallel to one another.
The Ritchie ledgers, now held by Ritchie Navigation, indicate that this
compass was produced on March 2, 1880, and sold to S. Thaxter & Son in
Boston. Smithsonian records indicate that Thaxter donated the compass to the
Smithsonian, perhaps for use in the International Fishery Exhibition which
opened in Berlin on April 20, 1880.