Prague Meridian (14°25´17˝) - Old Town Square
Can you spot the Meridian in Old Town Square?
The need to tell time accurately is much older than the widespread use of clocks; also it took a while before clocks could read time accurately. In order to determine when midday was, the so-called Prague Meridian was used from 1652 and indicated the place where the former Marian column used to cast its shadow at noon (there was no concept of summer and winter time back then).
Marian Column
Built in Old Town Square shortly after the Thirty Years' War in thanksgiving to the Virgin Mary Immaculate for helping in the fight with the Swedes. Unfortunately, many Czechs later connected its placement and erection with the hegemony of the Habsburgs in their country, and after declaring the independence of Czechoslovakia in 1918 a crowd of people pulled this old monument down and destroyed it in an excess of revolutionary fervor.
Accurate Prague time (Tempus Pragense) was in reality determined in the Astronomical tower of Clementinum using a chink sundial. From 1842, noontime was announced by waving a flag. Between 1891 and the 1920s, it was also accompanied by a shot from a cannon located in the castle bastion. After 1928, the astronomical recordings were moved to a new observatory in Ondřejov but the time announcement service remained in the tower until the occupation. From 1925, the Clementinum observatory provided a time signal for radio broadcasting. The time difference between what was recorded at the Clementinum observatory and the Meridian marked out by the shadow of the Marian Column was a mere one second and hence completely negligible in daily life.
Placed here in the 1900s, the plate reads, "MERIDIAN, ACCORDING TO WHICH TIME IN PRAGUE WAS DETERMINED"
