Circles of proportion
This is one of the earliest forms of slide rule. Calculations are performed on the circular scales arranged in a wide band towards the rim. Rather than with a sliding ring, these logarithmic scales were used with a (missing) pair of index rules hinged like dividers at the centre of the disc.
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
- Special Exhibition Label: 'Geek is Good' (15 May - 2 November 2014)
- Special Exhibition Label: 'Geek is Good' (15 May - 2 November 2014) - Slide rules general introduction
- Reverse prints taken from this instrument