Theodolite

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A theodolite is a surveying instrument for measuring horizontal and vertical angles. This brass example (pictured here with its fitted case) was made in France around 1770. It is unsigned.

The instrument consists of a compass with four fixed sights. However, measurements may be taken in both the horizontal and the vertical planes by tilting the instrument in the universal joint underneath the compass. Reasonably accurate angles could be taken for surveying purposes.

In areas where visibility is limited, for instance where the ground is thickly forested, conventional sighting instruments are of limited use and more reliance has to be placed on the compass. In this example, although unsigned, the directions are given in French: 'N.EST', 'S.EST', S.OUEST', 'N.OUEST'.

Record details

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• Online ID: 000-100-104-270-C
• Image Rights Holder: National Museums Scotland
• Project: National Museums Scotland
  Project description   View all records in project
• Ref: National Museums Scotland  T.1980.45
• Date: Around 1770
  c. 1770
  
• Material: Brass, glass / wooden case covered in leather. Inscription: Tooled motif of a fleur-de-lys on case
  Surveyor's dial / case
  
• Dimensions: 190 mm H x 160 mm x 160 mm
  
• What: Surveyor's dial / case
  
• Subject: 5. CARTOGRAPHY, Surveying (Departmental Classification)
  
• Who:
• Where: France
  
• Event:
• Description: Surveyor's dial, comprising French made brass compass and a wooden case covered with tooled leather
  
• References:
  • Bennett, J.A. The Divided Circle: A history of instruments for astronomy, navigation and surveying. Oxford: 1987. pp 83-8 
• Translations:
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