The Collection

Your selection



Buy this image Add this to a collection
Share or embed this object   

Please contact the Picture Library if you would like to use this record and image under licence.



Object connections:

User collections William Wales by NMMCollections
Gallery locationMaritime London Gallery (Floor plans)
Publication(s)Treasures of the National Maritime Museum
Gloria Clifton and Nigel Rigby
View this book in the library

Object details:

Object ID NAV1451
Description Theodolite in an octagonal wooden box. Base- Diameter 6.5" (16.5cm) is graduated 0-180 by 1 degree in each half, with three verniers, each marked to 30.It is fitted with two knobs, one to turn the instrument in azimuth, the other to clamp it. A tripod mounting socket, fitted with four levelling screws, is attached to a spigot at the centre of the underside of the base. Compass-Diameter 5.5" (14cm) with a blued steel needle with arrow heads at each end, is mounted at the centre of the base. The compass is graduated quadrantally in degrees. Vertical arc -Diameter 5.5" (14cm) with a mounting for a telescope is mounted above the base, and has rack teeth cut in its outer edge. It is graduated on one side 70-0-70 by 1 degree with vernier (30-0-30), and on the other side 15-0-15 (with veriner 20-0-20). Vernier scale is carried on a brass support with an ivory-ended spindle for turning arc in altitde. A spirit level in brass casing 2.25" (5.7cm) long is mounted on the lower part of the arc. Telescope -A modern replacement fitted with plain glass, no lenses. A similar instrument is illustrated in Gardiner, 'General Surveying Improved' (London, 1735)
Date made 1737

Artist/Maker Sisson, Jonathan
Place made London, England
Credit National Maritime Museum, Greenwich, London, Caird Collection
Materials glass; ivory; brass
Measurements Overall: 170 x 163 x 295 x 165 mm
Help us

Do you know more about this?

Share your knowledge