5311128 Illustration showing a Ring Dial or 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.; (add.info.: 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.); Universal History Archive/UIG.