Accession No
2341
Brief Description
universal equinoctial ring dial, English, 17th Century
Origin
England
Maker
Class
dials
Earliest Date
1625
Latest Date
1700
Inscription Date
Material
metal (brass)
Dimensions
diameter 115mm
Special Collection
Provenance
Bequeathed by R.S. Newall, 01/1978.
Inscription
Description Notes
Universal equinoctial ring dial, English, 17th Century.
Meridian ring calibrated for Northern latitudes, divided [0] - [90˚], numbered by 10˚, subdivided to 1˚; reverse carries altitude quadrant divided 0 - 90˚, numbered by 10˚, subdivided to 1˚. Suspension shackle missing. Equinoctial ring divided I - XII, I - XII (V-VII illegible), numbered by I, subdivided to 15 minutes. Pierced bridge with date scale divided to named (initialled) month, subdivided to 5 days; on reverse a zodiac scale, also a declination scale divided [23˚ 30´] - 0 - [23˚ 30´], numbered by 10˚, subdivided to 1˚. ‘N’ and ‘S’ marked on both sides of the bridge. Sliding pinhole gnomon.
Incomplete (shackle missing).
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:43159
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