Editing Anaximander (section)

=== Gnomon ===

The ''[[Suda]]'' relates that Anaximander explained some basic notions of geometry. It also mentions his interest in the measurement of time and associates him with the introduction in [[Greece]] of the gnomon. In [[Lacedaemon]], he participated in the construction, or at least in the adjustment, of [[sundial]]s to indicate [[solstice]]s and [[equinox]]es.<ref>These accomplishments are often attributed to him, notably by Diogenes Laertius (II, 1) and by the Roman historian [[Eusebius of Caesarea]], ''[[Preparation for the Gospel]]'' (X, 14, 11).</ref> Indeed, a [[gnomon]] required adjustments from a place to another because of the difference in [[latitude]].

In his time, the gnomon was simply a vertical pillar or rod mounted on a horizontal plane. The position of its shadow on the plane indicated the time of day. As it moves through its apparent course, the Sun draws a curve with the tip of the projected shadow, which is shortest at noon, when pointing due south. The variation in the tip's position at noon indicates the solar time and the seasons; the shadow is longest on the winter solstice and shortest on the summer solstice.

The invention of the gnomon itself cannot be attributed to Anaximander because its use, as well as the division of days into twelve parts, came from the [[Babylonia]]ns. It is they, according to [[Herodotus]]' [[Histories (Herodotus)|Histories]] (II, 109), who gave the Greeks the art of time measurement. It is likely that he was not the first to determine the solstices, because no calculation is necessary. On the other hand, equinoxes do not correspond to the middle point between the positions during solstices, as the Babylonians thought. As the ''Suda'' seems to suggest, it is very likely that with his knowledge of geometry, he became the first Greek to determine accurately the equinoxes.