A shepherd's dial (also known as a pillar dial or cylinder) is a type of

sundial A sundial is a horological device that tells the time of day (referred to as civil time in modern usage) when direct sunlight shines by the apparent position of the Sun in the sky. In the narrowest sense of the word, it consists of a flat ...

that measures the height of the sun via the so-called ''

umbra versa The umbra, penumbra and antumbra are three distinct parts of a shadow, created by any light source after impinging on an opaque object. Assuming no diffraction, for a collimated beam (such as a point source) of light, only the umbra is cast. Th ...

''. 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

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 . The earliest description of a shepherd's dial as known today was written by

Hermann of Reichenau Blessed Hermann of Reichenau (18 July 1013– 24 September 1054), also known by other names, was an 11th-century Benedictine monk and scholar. He composed works on history, music theory, mathematics, and astronomy, as well as many hymns. H ...

, an 11th-century Benedictine monk, who called it a . It was also known in the Middle Ages as a (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 ''Portrait of Nicolaus Kratzer'' is a 1528 half-length portrait by Hans Holbein the Younger. It is now in the Louvre, whilst a copy after it hangs in the National Portrait Gallery. It shows the astronomer Nikolaus Kratzer, a friend of Thomas M ...

'' and his 1533 '' The Ambassadors''.

Concept

Characteristics

Variants

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.

References

{{Reflist Sundials