Celestial navigation, Astronomical and navigational instruments

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Celestial navigation

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Object ID NAV1282
Description The octant is made from a mahogany frame and index arm, with a boxwood limb, brass fittings, a brass stop for the index arm and an inlaid ivory plate on the crossbar. There is no tangent screw and the clamping screw, which is missing, was on the back of the index arm. The octant has two socket shades in red and orange. Index-glass adjustment is made by a screw and on both horizon glasses by levers, wing nuts and wing nuts for clamping, one of which is missing. The sight vane has two pinholes and a swivelling shutter, now missing, and the back sight vane has one pinhole. The octant has no box. It has a boxwood transversal scale from 0° to 90° by 20 arcminutes, which is vice versa for the zenith distance, measuring to 90°. The scale reads to 1 arcminute by the fiducial edge of ivory at the end of the index arm. This instrument is the earliest dated English octant in the National Maritime Museum collection.
Date made 1753

Artist/Maker Adams, George
Place made London
Credit National Maritime Museum, Greenwich, London, Caird Collection
Materials ivory (CITES); wood; brass; glass; mahogany
Measurements 80 x 470 x 563 mm; Radius: 502 mm
  • Octant (NAV1282)
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