Accession No
0210
Brief Description
universal equinoctial ring dial, by Heath and Wing, English, 3/4 18th Century
Origin
England; London
Maker
Heath and Wing
Class
dials
Earliest Date
1750
Latest Date
1775
Inscription Date
Material
metal (brass, silver)
Dimensions
height 380mm; diameter 326mm; thickness 21mm
Special Collection
Robert Whipple collection
Provenance
Purchased by Robert Stewart Whipple from T. H. Court on 21/03/1925.
Inscription
‘Heath & Wing
London’ (shackle)
Description Notes
Brass, with meridian ring and bridge silvered.
Meridian ring calibrated for all latitudes, divided 0 - 90˚ - 0 - 90˚ - 0, numbered by 10˚, subdivided to 15´. Suspension shackle with brass suspension ring. Equinoctial ring divided I - XII, I - XII, numbered by I, subdivided to 2 minutes; similarly marked on inner face but only subdivided to 10 minutes. Pierced bridge with date scale divided to named month, subdivided to 1 day; reverse carries zodiac scale divided to sign and subdivided to 1˚ (1st Aries = 20 March) and declination scale divided 23˚ 30´ - Æ - 23˚ 30´, numbered by 10˚, subdivided to 15´.
Reverse of meridian ring with equation of time scale with date scale divided to 1 day against time in minutes and marked ‘Watch Slower’ and ‘Watch Faster’.
good condition
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:39998
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