Some Greek sundial meridians

Abstract

In Greco-Roman sundials, the indication of time of year often has a prominence comparable to the indication of time of day. The meridian hour-line offered a convenient scale for time of year, and we have instances of sundials reduced to just the meridian, so that the only time of day when a reading was possible was noon. The present paper discusses three interesting ancient meridian scales. The first, L Milet. inv. 46, was found during the German excavations at Miletos in the early 20th century. It has not been previously published or discussed in print, and its present location is not known, but a fairly precise drawing with measurements survives. This was a mere meridian inscribed on a south-facing vertical surface, with graduations marking the dates of the Sun's entries into the zodiacal signs. Brecda Alexandria Mus. No. 185 is an inscription explaining the use of a sundial that itself no longer exists. The surviving part of the text concerns how to read the stage of the year off the sundial; there were indications not only of the Sun's entries into the zodiacal signs but also of dates of stellar visibility phenomena, indexed by letters of the Greek alphabet. National History Museum of Romania inv. 18.757 is a sundial with a meridian marked at irregular intervals with letters of the Greek alphabet that again probably represent stellar visibility phenomena, though in this case the accompanying inscription identifying the phenomena is lost.