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17th-CENTURY BRASS UNIVERSAL EQUINOCTIAL RING DIAL
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Pre 1700 item# 932737
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Bernardo Antichita'
+39 055 214512
$ 6500
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A fine 17th-Century brass Universal Equinoctial Ring Dial.
The dial comprises two concentric rings and a bridge, folding flat when not in use, with a suspension ring and a bracket which moves in the grooved outer edges of the meridian ring. The obverse side of the meridian ring has a latitude scale. The hole for the pin used with the scale corresponds to 45° on the latitude scale. The obverse side of the equinoctial ring has an hour scale while the reverse is plain. On the bridge, one side carries a date scale and the other side features a zodiac scale on the upper bar and a declination scale on the lower bar. A sliding pinhole gnomon, adjustable for solar declination, is set between the bars of the bridge.
Netherlands, late 17th Century.
The universal equinoctial ring dial was developed from the astronomer's ring which was first mentioned by Gemma Frisius and other 16th century authors.
Described as “a simplified armillary sphere“, the astronomer's ring was used for measuring altitudes of stars and terrestrial objects.
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