Shepherd's dial
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A shepherd's dial (also known as a pillar dial or cylinder) is a type of sundial that measures the height of the sun via the so-called umbra versa.[1] Its design needs to incorporate a fixed latitude, but it is small and portable. It is named after Pyrenean shepherds, who would trace such a sundial on their staffs. This type of sundial was very popular in the 16th, 17th, and 18th centuries.
History[edit]
Since the ancient Roman era, people have created sundials which tell the time by measuring differences in the sun's height above the horizon over the course of the day – Vitruvius describes them as viatoria pensilia.[2] The earliest description of a shepherd's dial as known today was written by Hermann of Reichenau, an 11th-century Benedictine monk, who called it a cylindrus horarius. It was also known in the Middle Ages as a chilinder oxoniensis (Oxford cylinder). Such sundials did not need aligning north-south and so became very popular,[3] appearing in Renaissance artworks such as Holbein's 1528 Portrait of Nicolaus Kratzer and his 1533 The Ambassadors.[4]
Concept[edit]
Characteristics[edit]
Variants[edit]
A Slovenian shepherd's dial is a flat dial in the shape of a sector of a circle. It is hung vertically and measures the altitude of the sun. A movable peg adjusts for the changing seasons.[5]
References[edit]
- ^ Kren, Claudia (July 1977). "The Traveler's Dial in the Late Middle Ages: The Chilinder". Society for the History of Technology. 18 (3): 419–435.
- ^ De Solla Price, Derek (1969). "Portable sundials in the antiquity". Centaurus. 14: 242–266.
- ^ Mills, Allan A. (1996). "Altitude sundials for seasonal and equal hours". Annals of Science. 53 (1): 75–85. doi:10.1080/00033799600200121.
- ^ Stebbins, F. A. (1962). "The Astronomical Instruments in Holbein's "Ambassadors"". Journal of the Royal Astronomical Society of Canada. 56: 45. Bibcode:1962JRASC..56...45S.
- ^ "Webzine Sloveniana".