Unequal hours

They are unequal duration periods of time because days are longer and nights shorter in summer than in winter.

Their use in everyday life was replaced in the late Middle Ages by the now common ones of equal duration.

A division of day and night into twelve hours each was first recorded in Ancient Egypt.

A similar division of day and night was later made in the Mediterranean basin from about Classical Greek Antiquity into twelve temporal hours each (Ancient Greek: ὥραι καιρικαί, romanized: horai kairikai).

For the latter, the speed of the verge escapement (Waag) was changed, for example, in 26 steps (i.e., half the numerical value of 52 weeks).

Dial of a wall-mounted sundial [ de ] for the simultaneous display of temporal (black) and equinoctial (red) daylight hours with a dot-shaped shadow ( Nodus [ de ] ). The equinoctial hours are equal to the temporal hours at the equinoxes ; the lines of both types of hours intersect.
The astronomical clock of the Zytglogge in Bern shows the temporal hours on curved golden lines: respective end of the hour indicated with a black number.