"SPENCER, BARRETT & CO LONDON"
radius 9.75 inches
The Smithsonian received this octant from the U.S. Nautical Almanac in 1882. It was made in the mid-nineteenth century. It has an ebony frame, reinforced brass index arm, and ivory scale. The scale is graduated every 20 minutes from -3o to +109o and read by vernier with tangent screw to single minutes of arc.