Octant

Octant

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Description
Octant with an ebony frame, reinforced brass index arm, and ivory name plate. The ivory scale is graduated every 20 minutes from -3° to +100° and read by vernier with tangent screw to single minutes of arc. There is a telescopic sight, four shades for the index mirror, and three shades for the horizon glass. The inscription reads "SPENCER & CO LONDON." The radius is about 11 inches. The U.S. Navy transferred this to the Smithsonian in 1930.
Ref: Gloria Clifton, Directory of British Scientific Instrument Makers 1550-1851 (London, 1895), p. 83.
Location
Currently not on view
Object Name
octant
date made
early 19th century
maker
Spencer & Co.
place made
United Kingdom: England, London
Measurements
radius: 9 3/4 in; 24.765 cm
overall: 4 5/8 in x 9 7/8 in x 11 1/4 in; 11.7475 cm x 25.0825 cm x 28.575 cm
ID Number
PH.309887
catalog number
309887
accession number
110828
Credit Line
U.S. Navy
See more items in
Medicine and Science: Physical Sciences
Measuring & Mapping
Data Source
National Museum of American History
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