An American ebony and brass octant in a keystone box
Frye & Shaw, New York (American, 19th century)
A 9" radius octant with ivory scales and name-plate, filters, lens sight, brass arm, brass feet, thumb screw vernier adjuster, ebony and brass handle. In a keystone mahogany case with trade label of Costigan of New York on the inside cover of case. Also signed on the back of the ebony radius.
13 x 12 x 5 in. (33 x 30.5 x 12.7 cm.) box dimensions.