Special Exhibition Label: 'Geek is Good' (15 May - 2 November 2014)
Ingenious Calculation
Slide rules depend on logarithms, which were first published by John Napier in 1614. Shortly afterwards, the mathematician Edmund Gunter had the idea of turning logarithmic tables of numbers into a scale, on which he could operate with a pair of dividers. William Oughtred then thought of sliding two logarithmic scales against each other, creating a straight slide rule.
Oughtred also devised a circular instrument, the “Circles of Proportion”, whose calculating part is represented by the outer series of circular scales on this large brass disc. Missing from this example is a central pair of rotating arms, which are equivalent to the dividers in Gunter’s straight version. This example was made in 1635 or before, and is one of the oldest slide rules to survive.
MHS inv. 40847
Other narratives:
- Inventory No. 40847 & 35515 - Exhibition Label Text 'The Double Horizontal Dial: Then and Now' 13 January to 10 March 2009
- Inventory no. 40847 - Former Display Label
- Bennett, J. and Johnston, S., The Geometry of War, 1500-1750 (Oxford, 1996)
- Movable parts
- Circles of proportion
- Special Exhibition Label: 'Geek is Good' (15 May - 2 November 2014) - Slide rules general introduction
- Reverse prints taken from this instrument