Accession No
0968
Brief Description
standing universal equinoctial ring dial, by Heath and Wing, English, 3/4 18th Century
Origin
England; London; Strand
Maker
Heath and Wing
Class
dials
Earliest Date
1750
Latest Date
1775
Inscription Date
Material
metal (brass, steel); glass; wood
Dimensions
depth 350mm; breadth 340mm; height 455mm
Special Collection
Robert Whipple collection
Provenance
A. Hutchinson Collection.
Inscription
‘Made by Heath & Wing LONDON’ (base plate)
‘MADE BY HEATH & WING in ye Strand LONDON’ (compass rose)
Description Notes
Brass; set on 3 ‘claw’ feet with levelling screws; base plate with a knurled headed pin which rotates the whole dial on the base plate. Degree scale divided 0 - 90˚ - 0 - 90˚ - 0, numbered by 10˚, subdivided to 1˚ with vernier reading to 5´. Also on base plate an equation of time marked ‘WATCH FASTER WATCH SLOWER’ by minutes with associated date scale divided to named month, numbered by 10 days and subdivided to 1 day. Inset compass, all silvered; 16-point rose with fleur-de-lis for North; degree scale divided [0] - 360˚, numbered by 10˚, subdivided to 1˚. Also divided [0] - [90˚] - [0] - [90˚] - [0], numbered by 10˚. Two bubble levels inset into the compass rose at right angles.
Meridian ring set within fixed outer ring set on the dial plate and moved by knurled-headed screw. Divided [0] - 90˚ - [0] - 90˚ - [0], numbered by 10˚, subdivided to 1˚, with vernier on the suspension shackle reading to 5´. Reverse carries a list of towns and latitudes (see history file). Set on the meridian ring, parallel to the bridge are a pair of sights for measuring the sun’s altitude, with pinhole and lens with crosshairs.
Equinoctial ring divided I - XII, I - XII, numbered by I, subdivided to 2 minutes (calibrations on face and inside ring). Reverse carries a list of towns and latitudes.
Pierced bridge with date scale divided to named month, subdivided to 2 days; reverse carries zodiac scale divided to sign and subdivided to 2˚, also declination scale divided 23˚ 30´ - Æ - 23˚ 30´, numbered by 2˚, subdivided to 30´. Double pinhole gnomon.
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:40013
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