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Description: | Forged vertical disc dial with no measurable latitude. It is made of brass, has a fixed hanging loop and the suspension ring is missing. On the obverse side, a time curve is drawn from the top of the dial in an arc to the right. There is floral decoration and a decorated rim where there are no scales. A declination scale at the top left of the dial is divided from solstice to solstice and marked by month. On the opposite edge is a scale for the time of sunrise. Both these scales have a slot set inside them. The brass pin gnomon moves in the slot of the declination scale.
The reverse side has a brass strip pivoted at its centre, which holds the gnomon at one end and an index at the other (which slides in the sunrise scale). The equinoxes given in the date scale of this instrument are wrong, as are the hour numbers. The maker appears to have known that the Italians used a 24-hour system but not that it began at sunset, and so has numbered the hours as if the system began at midnight. The scale for the time of sunrise is not symmetrical.
For more information regarding this dial please refer to the OUP & NMM catalogue, 'Sundials at Greenwich'.
caption: Forged vertical disc dial
caption: Forged vertical disc dial, reverse | Publisher: | "http://collections.rmg.co.uk/" | Rights holder: | "Royal Museums Greenwich" | Subjects: | Vertical disc dial vertical dials Sundials at Greenwich Altitude Dial | Source: | Royal Museums Greenwich | Identifier: | http://collections.rmg.co.uk/collections... | Go to resource |
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