Surveyors' sextant

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This surveyor's sextant was made around 1850, probably by Troughton and Simms, scientific instrument makers based in London. It is made of brass, with a silvered scale and is fitted with a reading microscope and a pillar stand.

This form of instrument is basically a conventional nautical sextant with a counterbalanced stand which converts it into a theodolite. The instrument can be swung vertically or horizontally to take readings in two planes.

The donor of this instrument was involved in surveying the freshwater lochs of Scotland, and it is probable that the instrument was used in a boat to fix its position relative to various shore stations.

Record details

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• Online ID: 000-180-001-170-C
• Image Rights Holder: National Museums Scotland
• Project: National Museums Scotland Part 2
  Project description   View all records in project
• Ref: National Museums Scotland  T.1928.141
• Date: Around 1850
  
• Material: Brass, silver / mahogany cases
  Sextant, surveyor's / pillar stand / case
  
• Dimensions:
• What: Sextant, surveyor's / pillar stand / case
  
• Subject:
• Who: Troughton and Simms, London (Instrument maker)
  
• Where: England, London
  
• Event:
• Description: Surveyor's sextant of brass fitted with reading microscope, with a pillar stand, made by Troughton and Simms, London, in two mahogany cases
  
• References:
  • For a similar (but earlier) instrument by Edward Troughton, see J.A. Bennett, The Divided Circle: a History of Instruments for Astronomy, Navigation and Surveying, Oxford, 1987, p 138 
  • For Troughton & Simms, see Anita McConnell, Instrument Makers to the World: a History of Cooke, Troughton & Simms, York, 1992. 
  • Stanley, W.F., Surveying and Levelling Instruments Theoretically and Practically Described 3rd edition, London, 1901, pp 426-7 
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