
4 0 c m
33cm
actual image size: 25cm x 32cm
Description
Octant with a wooden frame inlaid with ivory scales and naked-eye sights, made by S W Silver & Company of London. This instrument would have been used for navigation on a ship. The octant could be used to find 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 it with a chronometer set to a fixed meridian. The angle between the fixed stars and the Moon could also be measured to discover longitude using lengthy calculations and tables from the Nautical Almanac.
Image Details
Image Ref.
10326299
© Science Museum / Science & Society Picture Library