Octant (detail)

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An octant is a navigational instrument used for measuring angles necessary for determining a ship's position at sea. This is a detail from an octant made in 1744, probably by Edward Nairne (1726-1806), a scientific instrument maker based in London.

The detail shows the arc and, at the top, an ivory plate inscribed 'Thomas Hellyer [the owner] 1774/ NAIRNE LONDON'.

Until around 1780, a central zero was common on the vernier of octants, as seen here; after this date the vernier had the zero to the right.

Record details

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• Online ID: 000-190-002-051-C
• Image Rights Holder: National Museums Scotland
• Project: National Museums Scotland
  Project description   View all records in project
• Ref: National Museums Scotland  T.1909.9
• Date: 1774
  
• Material: Octant
  
• Dimensions:
• What: Octant
  
• Subject: 9. NAVIGATION (Departmental Classification)
  
• Who: Nairne, London (Maker)
  
• Where: England, London
  
• Event:
• Description: Octant made by Nairne, London, dated 1774
  
• References:
  • Bennett, J.A. The Divided Circle: A history of instruments for astronomy, navigation and surveying. Oxford: 1987, pp 132-4 
  • For Nairne, see Clifton, Gloria, Directory of British Scientific Instrument Makers 1550-1851. London: 1995, p 196 
• Translations:
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