Astronomical and navigational instruments, Celestial navigation

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Astronomical and navigational instruments

Object connections:

Collection Astronomical and navigational instruments, Celestial navigation
Gallery locationNot on display

Object details:

Object ID NAV1117
Description The sextant has an ebony frame and limb with a brass index arm and fittings. It also has a wooden handle and an inlaid ivory plate on the crossbar. The tangent screw and clamping screw are located on the back of the index arm. The sextant has four shades, three 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 square-headed screw, a detached key, a lever, worm gear and a milled knob. Attached to the sextant is a magnifier on a 93mm swivelling arm. There is also a threaded telescope bracket in two parts, fitted for correcting collimation error. It has perpendicular adjustment made by a rising-piece and a milled knob. The telescope is 83 mm in length with an erect image. A second telescope is 173 mm long with an inverted image and four cross wires. The sight-tube is 82 mm in length and has a green shaded eyepiece and a milled adjusting key. The instrument has an inlaid ivory scale from -5° to 137° by 10 arcminutes, measuring to 118°. The sextant has an ivory vernier measuring to 10 arcseconds, with zero at the right. The sextant is contained in a mahogany keystone box, with a trade label in the lid for John Parkes and Sons, Liverpool, and a handwritten,‘1913 E. Company 5th Batt. Essex Reg. Hon. Members 1st Prize Awarded to E.T. Adams’. Owens was a clock and watchmaker and perhaps the retailer rather than the manufacturer of this instrument.
Date made circa 1850

Artist/Maker Owens, Owen
Place made Liverpool, Merseyside, England
Credit National Maritime Museum, Greenwich, London, Adams Collection
Materials organic: ivory; wood: ebony
Measurements Overall: 105 mm x 245 mm x 235 mm
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