Nocturnal (back)

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A nocturnal shows the local time at night, by measuring the rotation of the constellations of the Great Bear and the Little Bear around the Pole Star. This example was made in England around 1760. The photograph shows the back of the instrument.

The back of the nocturnal has two concentric scales giving the corrections to the altitude of the Pole Star for use in finding latitude. These are used together with the long index arm.

This instrument was probably used mainly by navigators, and the skilled practitioner could expect to be accurate within 15 minutes. The instrument was introduced in the 16th century and remained popular until the mid 18th century.

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• Online ID: 000-190-001-033-C
• Image Rights Holder: National Museums Scotland
• Project: National Museums Scotland
  Project description   View all records in project
• Ref: National Museums Scotland  T.1944.3
• Date: Around 1760
  c. 1760
  
• Material: Pear wood. Inscription: New stil [on arm]
  Nocturnal
  
• Dimensions: 4.25" D (circle); 7.31" radius (arm)
  
• What: Nocturnal
  
• Subject: 3. ASTRONOMY, Nocturnals (Departmental Classification)
  
• Who:
• Where: England
  
• Event:
• Description: Nocturnal in boxwood with "New stil" on arm, England, c. 1760
  
• References:
  • For nocturnals in general, see Bennett, J.A., The Divided Circle: A history of instruments for astronomy, navigation and surveying. Oxford: 1987, pp 77-78 
• Translations:
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