Accession No
1746
Brief Description
ring dial, Italian, 1588
Origin
Rome; Italy
Maker
Class
dials
Earliest Date
1588
Latest Date
1588
Inscription Date
1588
Material
metal (gilt brass)
Dimensions
length 82mm; diameter 65mm; thickness 14mm
Special Collection
Holden-White collection
Provenance
On loan from The Fitzwilliam Museum, University of Cambridge. Donated by Charles Holden-White to the Fitzwilliam Museum. C. Holden-White collection no. 1935-100.
Inscription
‘COELI ENARRAT GLORIAM DEI. ROMMAE AO DOMINE. M.D.L. XXXVIII POLVS XLII GRADVM’
Description Notes
Gilt brass ring dial for 42˚ N. Ring turned with raised edges on the outer face. Fixed suspension shackle with supension ring. Inscribed ‘COELI ENARRAT GLORIAM DEI’ (The Heavens declare the glory of God’). Two pinhole gnomons marked ‘Hye: Aut=’ and ‘Veris AEst=’. On the inner face are two hours scales for Italian hours with the relevant months marked by initial; one divided 12 - 24, numbered by 1; the other divided 9 - 24, numbered by 1. Shortest and longest day noons at 19hrs 32mins and 16hrs 28mins respectively.
Condition
References
Events
Description
Ring Dial
The ring dial is one of the oldest forms of portable sundial. It was probably developed by the Romans. It is also one of the simplest dials, and was often made very cheaply for the lower end of the market.
Ring dials tell the time from the height of the sun in the sky. They are generally not very accurate. They are used by moving the central band until the pin-hole is lined up against the correct date. After this, the dial is held up and turned until the sunlight falls through the pin-hole onto the hour scale on the other side of the ring. The small circle of light will show the hour, though it is left up to the user to work out whether to choose the morning or the afternoon reading.
FM:41411
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