Astronomical and navigational instruments, Celestial navigation

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Sextant

NAV1113
Astronomical and navigational instruments

Object connections:

Collection Astronomical and navigational instruments, Celestial navigation
User collections William Wales by NMMCollections
Gallery locationNot on display

Object details:

Object ID NAV1113
Description The sextant has a black-lacquered brass diamond-pattern frame with a wooden handle. The tangent screw and clamping screw are located on the back of the index arm. The sextant has three shades, two red and one green, and three horizon shades, two red and one green. Index-glass adjustment is made by a screw and on the horizon glass by a fixed milled screw and two capstan screws. Attached to the sextant are a magnifier on an 80mm swivelling arm, aswell as a threaded telescope bracket with perpendicular adjustment. This is adjusted by a rising-piece and a milled knob. The telescope is 129 mm in length with an inverted image and two parallel cross wires. It has a shaded eyepiece, which is missing, and an adjusting pin. The sextant is contained in a polished mahogany keystone box, with a trade label in the lid for Henry Hughes and Son, 59 Fenchurch Street, London. The instrument has a bright brass scale from -4° to 136° by 20 arcminutes, measuring to 120°. The sextant’s vernier measures to 30 arcseconds, with zero at the right.
Date made circa 1785

Artist/Maker Dollond & Aitchison
Place made London, England
Credit National Maritime Museum, Greenwich, London, Adams Collection
Materials metal: brass
Measurements Overall: 112 mm x 350 mm x 373 mm
Parts
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