Theodolite (detail)

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This is a detail of a theodolite, a surveying instrument for measuring horizontal and vertical angles. This theodolite was made around 1850, probably by Alexander Adie & Son of Edinburgh. It was designed in 1844 by John Sang, a land surveyor.

The detail shows the theodolite's horizontal circle, which calibrated from 0 to 400 grades, rather than from 0 to 360 degrees. This was a mid 19th century attempt at decimalisation (100 degrees to the quarter circle rather than 90).

The existence of instruments divided into grades (400 to the revolution) rather than degrees suggests that the firm Alexander Adie & Son had equipment that could handle division in this system also.

Record details

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• Online ID: 000-190-001-050-C
• Image Rights Holder: National Museums Scotland
• Project: National Museums Scotland
  Project description   View all records in project
• Ref: National Museums Scotland  T.1971.16
• Date: Around 1850
  c. 1850
  
• Material: Blackened brass, silver scales. Inscription: Adie & Son / Edinburgh
  Theodolite
  
• Dimensions: 220 mm H overall
  
• What: Theodolite
  
• Subject: 5. CARTOGRAPHY, Surveying (Departmental Classification)
  
• Who: Adie and Son, Edinburgh (Maker)
  
• Where: Scotland, Midlothian, Edinburgh
  
• Event:
• Description: Four-inch theodolite of brass, signed by Adie and Son of Edinburgh, c. 1850
  
• References:
  • Sang, John. 'Description of an Improved Apparatus for Levelling Small Theodolites', Transactions of the Royal Scottish Society of Arts 2. (1844) pp 306-7 
• Translations:
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