Numbering rods, associated with John Napier of Merchiston

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This set of wooden numbering rods for doing arithmetical calculations dates from the 18th century. The rods are known as 'Napiers's Bones' after John Napier of Merchiston (1550-1617), inventor of logarithms.

The rods were used to convert multiplication and division into simpler problems of addition and subtraction. They appear to be in their original box, although the manuscript inscription that they were used by Napier himself seems to have no foundation.

Napiers's Bones are so named because early sets were made in ivory. Napier described their use in his 'Rabdologiae' published in 1617, although he had been working on his ideas for around 20 years before publication.

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• Online ID: 000-100-102-353-C
• Image Rights Holder: National Museums Scotland
• Project: National Museums Scotland
  Project description   View all records in project
• Ref: National Museums Scotland  H.NL 38
• Date: 18th century
  
• Material: Wood
  Rod, mathematical / Napier's bones
  
• Dimensions:
• What: Rod, mathematical / Napier's bones
  
• Subject: Jewellery: clocks, watches (NMAS Classification)
  
• Who: John Napier (Inventor)
  
• Where: Scotland, Midlothian, Edinburgh (Merchiston)
  
• Event:
• Description: Set of Napier's bones of wood, invented by John Napier of Merchiston for the purpose of performing mechanically the operations of multiplication and division, 18th century
  
• References:
  • For how they work, see Bryden, D. J., Napier's Bones: A History and Instruction Manual. London: 1992 
  • For Napier's Bones generally, see Turner, G. L'E., Antique Scientific Instruments. Poole: 1980, p 109 
• Translations:
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