Accession No
1011
Brief Description
universal equinoctial ring dial, by John England, English, 1703
Origin
England; London; Charing Cross
Maker
England, John
Class
dials
Earliest Date
1703
Latest Date
1703
Inscription Date
1703
Material
metal (brass)
Dimensions
meridian ring outside diameter 257mm; thickness 8mm
Special Collection
Trinity College collection
Provenance
On loan from Trinity College, University of Cambridge from 1951.
Inscription
‘Made by Iohn England Charing Cross London’ (meridian ring)
‘COLLEG TRINIT CANTAB 1703’ (meridian ring)
Description Notes
Brass universal equinoctial ring dial.
Suspension shackle with 2 brass suspension rings.
Meridian ring calibrated for all latitudes, divided 90˚ - Æ[0] - [90˚], numbered by 10˚, subdivided to 30´. Reverse has an altitude quadrant divided 0 - 90˚, numbered by 10˚, subdivided to 30´.
Equinoctial ring divided I - XII, I - XII, numbered by I, subdivided to 5 minutes; also so divided on the inner face.
Pierced bridge with date scale divided to named months (Ian:, Feb:, March, April, May, Iune, Iuly, Aug, Sep, Octo, Nov, Dec), subdivided to 1 day. On the reverse a declination scale marked ‘[sun] Dec:’, divided [23˚ 30´] - 0 - [23˚ 30´], numbered by 10˚, subdivided to 30´. Also a zodiacal scale marked ‘[sun] place’, divided to the zodiacal sign (marked by symbol), graduated to 1˚. Vernal equinox at March 10.
Pinhole gnomon.
Condition good; complete.
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:40011
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