Slide rule (2 of 2)

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This slide rule for lunar calculations was made around 1820, probably by R. B. Bate, a scientific instrument maker based in London. It was designed in 1816 by David Thomson (1789-1834), an Arbroath merchant captain. The rule was used in the calculation of longitude by the lunar distance method.

This side of the wooden three-foot scale is marked 'TIME SIDE', has one central slider, and is stamped with various time and latitude scales.

Robert Brettell Bate published and sold both the scale itself and the instruction book which went with it in 1816. The second edition of Thomson's booklet was published in 1823. Bate was an instrument maker who managed to command a number of government contracts, and run a substantial sub-contracting operation, covering large sections of the London trade, including wooden scale making.

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• Online ID: 000-190-002-268-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.2.120 B
• Date: Around 1820
  c. 1820
  
• Material: Inscription: 14
  Slide rule, lunar
  
• Dimensions:
• What: Slide rule, lunar
  
• Subject:
• Who: R. Bate, London (Maker)
  
• Where: England, London
  
• Event:
• Description: Slide rule for lunar calculations, by R. Bate of London, c. 1820
  
• References:
  • Anita McConnell, R.B. Bate of the Poultry 1782-1847, London, 1993, pp. 33-34For Thomson, see E.G.R. Taylor, The Mathematical Practitioners of Hanoverian England 1714-1840, Cambridge, 1966, pp 407-8. 
  • David Thomson, Description & Use of the Longitude Scale or Lunar Corrector, for readily clearing Apparent Lunar Distances from effects of parallax & refraction, etc., London, 1816. 
  • For the lunar distance method, see E.G.R. Taylor, The Haven-Finding Art, London, 1956, pp 245-263; and Derek Howse, Nevil Maskelyne: the Seaman's Astronomer, Cambridge, 1989. 
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