Telescope micrometer

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A telescope micrometer was used for measuring small angular distances between stars. This example appears to have been ordered for use at the Royal Observatory in Edinburgh. It was made in 1736, probably by Thomas Heath of London.

It would have been used mounted in a telescope, with cross-hairs across the aperture (now missing). By turning the long screw by the ivory handle (a counter is set into the dial) the inner plate is turned against a scale showing the angle produced.

The date on the item means that the most likely candidate to have used it would have been Colin Maclaurin (1698-1746), Professor of Mathematics at the University of Edinburgh, who was lobbying for funds for astronomical activities in the 1730s.

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• Online ID: 000-100-103-376-C
• Image Rights Holder: National Museums Scotland
• Project: National Museums Scotland
  Project description   View all records in project
• Ref: National Museums Scotland  T.1986.L.2.18
• Date: 1736
  
• Material: Micrometer, telescope
  
• Dimensions:
• What: Micrometer, telescope
  
• Subject:
• Who: Thomas Heath, London (Maker)
  
• Where: England, London
  
• Event:
• Description: Telescope micrometer, by Thomas Heath of London, 1736
  
• References:
  • Macdonald, A. & Morrison-Low, A.D., A Heavenly Library: Treasures from the Royal Observatory's Crawford Collection. Edinburgh: Royal Observatory & NMS, 1994, p 47 
  • Smith, Robert., A Compleat System of Opticks. Cambridge, 1738, pp 345-9 
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