"Owens Liverpool" and "John Nickels.1797"
radius 14 inches
This octant has an ebony frame, flat brass index arm, and ivory name plate.
The ivory scale is graduated every 20 minutes from -2o to +99o and read by tangent screw and vernier to single minutes of arc. There is also a back sight and a back horizon glass that can be used to measure angles greater than 90o. The Society of Oldest Inhabitants of Washington, D.C. donated it to the Smithsonian in 1968.