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. 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.
1 History 2 Concept 3 Variants 4 References
History Since the ancient Roman era, people have created sundials which measure differences in the sun's height above the horizon over the course of the day - Vitruvius describes them as viatoria pensilia. 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, appearing in Renaissance artworks such as Holbein's 1528 Portrait of Nicolaus Kratzer and his 1533 The Ambassadors. Concept Main article: Diurnal motion Variants References
^ Claudia Kren, (1977), The Traveler's Dial in the Late Middle Ages: The Chilinder, Society for the History of Technology, Vol. 18, No. 3 (Jul., 1977), pp. 419-435 ^ Derek De Solla Price, (1969), "Portable sundials in the antiquity", Centaurus, 14, págs. 242-266 ^ Allan A. Mills, (1996), Altitude sundials for seasonal and equal hours, Annals of Science, Vol. 53, nº 1, DOI: 10.1080/00033799600200121, pags. 75-85 ^ Stebbins, F. A., (1962), The Astronomical Instruments in Holbein's "Ambassadors", Journal of the Royal Astronomical Society of Canada