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Octant

Catalogue number:
PH*309887

Inscriptions:
"SPENCER & C^O LONDON"

Dimensions:
radius 9.75 inches

Discussion:
This octant has an ebony frame, reinforced brass index arm, and ivory name plate. The ivory scale is graduated every 20 minutes from -3^o to +100^o 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 U.S. Navy transferred this instrument to the Smithsonian in 1930.

Ref: Gloria Clifton, Directory of British Scientific Instrument Makers 1550-1851 (London, 1895), p. 83.

Further Information:

Spencer & Co.
Octant