English sextant with pillar stand, 1788-1804

Double A-frame sextant of 12 inch radius, 1788-1803.
Dated to the late eighteenth century, this brass sextant was made by the London instrument makers, John and Edward Trougton. With its tripod stand and telescopic sights, it was designed for use in navigation, surveying and hydrography. The sextant could be used to find your latitude by measuring the height of the midday Sun or a suitable star at night. Longitude could also be found from determining local noon from the maximum height of the Sun and comparing that time with a chronometer set to a fixed meridian. The angle between the fixed stars and the Moon could also be used to find longitude after lengthy calculations using tables in the Nautical Almanac.
Currently on display in:
Making the Modern World
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