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GERMAN UNIVERSAL EQUINOXIAL RING DIAL. A fine brass universal equinoctial sundial, German. Late 17th Century. The chapter ring engraved with an hour scale of twice twelve hours on one upper surface, with half-hour subdivisions. The equinoctial ring with sliding suspension loop and engraved with a 0-90° scale with 1° subdivisions and a list of central European cities and their latitudes. The bridge with sliding pinhole sight, the calendar scale engraved on one side, the scale on the reverse with engraved sigils for the houses of the Zodiac. • Diameter: 72 mm. • History of the equinoctial ring dial. 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 consisting of three or four rings, with pinhole sights', the astronomer's ring was used for measuring altitudes of stars and terrestrial objects. A two-ring dial (far more common than a three-ring dial) soon developed from this type of instrument. This replaced the innermost ring with a bridging bar containing a central slot, in which a sliding pinhole sight could move along a date scale. This instrument was designed by the English mathematician, William Oughtred, in the first half of the 17th century. Early versions carried only a date scale on the bridge and were normally for use in northern latitudes alone. Towards the end of the 17th century, zodiac and solar declination scales were added to the bridge and a further degree scale was supplied to allow use of the instrument in southern latitudes. At the same time, an altitude quadrant appeared on the back, which was used for measuring heights, in conjunction with a stylus set in a hole in the back of the instrument. These adjustments made the universal equinoctial ring dial a particularly suitable dial for use at sea.

Price:  B.

 

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CRIJNS & STENDER
Landgoed "Oosterheide"
Tilburgse Baan 1
4904 SP Oosterhout
Netherlands.
tel +31 (0)76 587 57 00
Opening times:
By appointment only.

Website: www.crijns.info
Also at:
Ginnekenweg 328,
4835 NL Breda.
tel +31 (0)76 560 01 02
Opening times:
Friday and Saturday
From 10 A.M. till 5 P.M.
and by appointment

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