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The Meridian Hall (Meridiánová síň)
This mysterious room is located on the 2nd floor of the Clementinum’s Astronomical Tower; it has been hiding a unique slotted sundial behind its door since the 18th century. Through a small hole high in the wall, a ray of sunlight penetrated and turned the small space into a camera obscura. The sunlight fell on a string stretched on the floor and their fusion determined with great precision the moment of noon, the exact time when the sun is at its highest point in its imaginary orbit. Two original astronomical instruments - mural quadrants - have also been preserved in the walls of the hall.
- Monuments & Architecture
- technical monument
- Baroque
Practical information
The Meridian Hall is part of the sightseeing route The Clementinum Astronomical Tower and Baroque Library.
Contacts
- The Meridian Hall (Meridiánová síň)
- Klementinum 190
- 110 00 Praha 1 – Staré Město
- +420221714714
Object history
In addition to the mural quadrants (instruments for determining the meridian passages of stars and measuring the angular distances between celestial bodies and their height above the horizon) located in the south window and the north opening of the room, there are also remnants of the mechanism for tensioning the meridian string that defines the local meridian. In order for the device determining noon to work year-round, the string had to be stretched across the room because of the angular distance of the sun from the world’s equator, which changes throughout the year.
The announcement of noon from the gallery of the Astronomical Tower was initiated by the Supreme Burgrave of the Kingdom of Bohemia, Count Karel Chotek. A flag in the provincial colours of red and white was used to signal every noon from 20 July 1842 to 31 January 1928. Since 1925, the exact time was broadcast from Clementinum by radio and therefore the noon signal from the tower lost its significance.
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Information source: Prague City Tourism