Astronomical and navigational instruments, Celestial navigation

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Octant

NAV1344
Astronomical and navigational instruments

Object connections:

Collection Astronomical and navigational instruments, Celestial navigation
ExhibitionsNelson, Navy, Nation
User collections Collectables (All) by blueheatwave
Collectables (UK) by blueheatwave
Gallery locationNelson, Navy, Nation Gallery (Floor plans)
PeopleProvenance: Cambell, James

Object details:

Object ID NAV1344
Description The octant has an ebony frame and limb with a brass index arm, fittings, and a stop for the index arm. It also has an inlaid ivory plate on the crossbar and inlaid decorative ivory strips along all edges of the front of the frame. There is no tangent screw, and the clamping screw, which is missing, is on the back of the index arm. The socket shades are also missing. Index-glass adjustment is made by a screw and both horizon glasses by levers, wing nuts, and milled clamping screws. The sight vane has two pinholes and a swivelling shutter, whereas the back sight vane has one pinhole and is fastened to the brass back horizon glass mount. A pencil or screwdriver, one wing nut, and a clamping screw are missing from the crossbar. The octant has no box. The instrument has an inlaid ivory scale in two sections (joined at 50°) from -5° to 95° by 20 arcminutes, measuring to 92°. The octant has an ivory vernier measuring to 1 arcminute, with zero at the centre.
Date made circa 1770

Artist/Maker Unknown
Place made England, United Kingdom
Credit National Maritime Museum, Greenwich, London
Materials brass; ivory; ebony
Measurements Overall: 130 x 340 x 270 mm
Parts
  • Octant (NAV1344)
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