Accession No
2340
Brief Description
universal equinoctial ring dial, by W & S Jones, c.1800
Origin
30 Holborn; London; England
Maker
W & S Jones
Class
dials
Earliest Date
1800
Latest Date
1800
Inscription Date
Material
metal (brass)
Dimensions
length 132mm; diameter 105mm
Special Collection
Provenance
Bequeathed by R.S. Newall, 01/1978.
Inscription
‘W & S JONES. 30 Holborn LONDON’ (on meridian circle)
Description Notes
Meridian ring calibrated for all latitudes, divided 90˚ - 0 - 90˚, numbered by 10˚, subdivided to 1˚, ‘0’ marked ‘SN’; reverse carries altitude quadrant divided 0 - 90˚, numbered by 10˚, subdivided to 1˚. Suspension shackle with brass suspension ring. Equinoctial ring divided I - XII, I - XII, numbered by I, subdivided to 7 1/2 minutes; similarly divided on inner face. Pierced bridge with date scale divided to named (initialled) month, subdivided to 5 days, with symbols of zodiac marked on reverse; also on reverse a declination scale divided [23˚ 30´] - AE (0) - [23˚ 30´], numbered by 10˚, subdivided to 1˚. Sliding pinhole gnomon.
One of screws on bridge support is loose.
(Are hour ring stops replacements?; 17-1-2000)
Condition: good.
References
Events
Description
The universal equinoctial ring dial was designed by the English mathematician William Oughtred in the first half of the seventeenth century. It could be used at any latitude, so was a popular timekeeper for sailors and other travellers. It was really a much simplified version of the armillary sphere, only keeping the parts which were needed for telling the time.
The universal equinoctial ring dial consists of two rings and a bridging bar inside the inner ring. The outer ring represents a circle passing through the North and South celestial poles. The inner ring is called the ‘equinoctial’ ring because it represents the celestial equator. The bridging bar represents the axis of the world, just as the gnomon on an ordinary horizontal dial does. So the instrument is a very simple model of the heavens.
01/02/2001
Created by: Dr Hester Higton on 01/02/2001
FM:40009
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