According to a Suda* s.v.:
Anaximander, son of Praxiades, of Miletus:
....was the first to discover a gnomon, and he set up one of the
Sundials in Sparta, according to Favorinus in his Universal History, to
mark solstices and equinoxes; and he also constructed hour indicators....
(*as quoted in Kirk, Raven, and Schofield, p.100.)