Octant

Octant

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Description
This octant, which probably dates from the late eighteenth century, has a mahogany frame and index arm. The boxwood scale is graduated every 20 minutes from 0 to 90 degrees and read by transversals to 2 minutes of arc. The top of the scale is numbered counterclockwise for zenith distances. There is also a back sight and a back horizon glass that can be used to measure angles greater than 90°.
Location
Currently not on view
Object Name
octant
date made
late 18th century
Measurements
overall: 7.6 cm x 37.8 cm x 46 cm; 3 in x 14 7/8 in x 18 1/8 in
overall: 3 in x 14 7/8 in x 18 1/4 in; 7.62 cm x 37.7825 cm x 46.355 cm
ID Number
PH.314493
catalog number
314493
accession number
204107
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Data Source
National Museum of American History
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