What are the Lower Back Dials "Glyphs"?

What are the Lower Back Dials "Glyphs"?

The remaining fragments of the lower back dial contain 16 sets of characters which were inscribed within some of the 223 divisions of the spiral dial. Each set of characters or "glyph" consists of 4 to 10 characters. Nearly all the glyphs contain S (lunar eclipse, from SELHNH, Moon) or H (solar eclipse, from HLIOS, Sun). Some glyphs contain both lunar and solar eclipse. In each case the hour (after sunrise, or sunset) is given. Some glyphs have a pair of characters that may be interpreted as an abbreviation of “day” (hemera) – possibly indicating that the (predicted lunar) eclipse was diurnal. The last character(s) in each case provide an alphabetical index, perhaps used cross reference the glyphs to some other text. The lower back dial displayed the 223 synodic months of the Saros cycle, with a subsidiary dial displaying the Triple Saros or Exeligmos cycle. By using these dials in combination, it would have been possible to use the mechanism to predict the time (hour, day, month, & year) of both lunar and solar eclipses.

Further reading:



  1. Calendars with Olympiad display and eclipse prediction on the Antikythera Mechanism,
    Freeth, Tony, Jones Alexander R., Steele John M., and Bitsakis Yanis
    , Nature, 07/2008, Volume 454, p.614-617, (2008)