Spencer, Barrett & Co. Octant

The Smithsonian received this octant from the U.S. Nautical Almanac in 1882. It has an ebony frame, reinforced brass index arm, and ivory scale. The scale is graduated every 20 minutes from -3° to +109° and read by vernier with tangent screw to single minutes of arc. The inscription reads "SPENCER, BARRETT & CO LONDON."
Currently not on view
Object Name
date made
mid 19th century
Spencer, Barrett & Co.
radius: 9 3/4 in; 24.765 cm
overall: 12 in x 9 7/8 in x 3 3/16 in; 30.48 cm x 25.0825 cm x 8.09625 cm
overall: 12 1/4 in x 9 3/4 in x 3 in; 31.115 cm x 24.765 cm x 7.62 cm
place made
United Kingdom: England, London
ID Number
catalog number
accession number
Measuring & Mapping
See more items in
Medicine and Science: Physical Sciences
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
U.S. Nautical Almanac
Additional Media

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