The earliest time-measuring devices were sundials, water clocks and astrolabes. These were already used in antiquity and became popular during medieval times. The candle clock was introduced in the 9th century, followed by the sand glass in the 13th century. The earliest European mechanical clocks also date from the 13th century. These were turretclocks and small turret watchman's clocks.
The earliest mention of Dutch turretclocks date from the second half of the 14th century. At that time the length of the hour was then still adjusted to the length of daylight and the length of a diurnal hour and a nocturnal hour varied with the seasons. However, domestic clocks usually showed hours of equal length