Accession No
1662
Brief Description
universal equinoctial ring dial, by Benjamin Martin, English, 3/4 18th Century
Origin
England; London
Maker
Martin, Benjamin
Class
dials
Earliest Date
1750
Latest Date
1775
Inscription Date
Material
metal (brass)
Dimensions
length 117mm; diameter 105mm (length 144mm; diameter 115mm; 17-1-2000)
Special Collection
Fitzwilliam collection
Provenance
On loan from The Fitzwilliam Museum, University of Cambridge. No. B32 from the Spencer George Percival Bequest, 1923.
Inscription
‘B. MARTIN FECIT’ (meridian ring)
Description Notes
Meridian ring calibrated for all latitudes, divided 90˚ - 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. Reverse carries altitude quadrant divided 0 - 90˚, numbered by 10˚, subdivided to 1˚. Pierced bridge with date scale divided to named (initialled) month, subdivided to 5 days; on reverse a zodiac scale divided to sign, also a declination scale divided [23˚ 30´] - 0 - [23˚ 30´], numbered by 10˚, subdivided to 1˚ (1st Aries = 20 March). Sliding pinhole gnomon. (‘N’ and ‘S’ marked on both sides of bridge; 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:40000
Images (Click to view full size):
