The Jayrun Water Clock, a water clock

Water clock

A water clock or clepsydra is any timepiece in which time is measured by the regulated flow of liquid into or out from a vessel where the amount is then measured.Water clocks, along with sundials, are likely to be the oldest time-measuring instruments, with the only exceptions...

 built by the Arab engineer Muhammad al-Sa'ati, was positioned at the gate of Damascus

Damascus

Damascus , commonly known in Syria as Al Sham , and as the City of Jasmine , is the capital and the second largest city of Syria after Aleppo, both are part of the country's 14 governorates. In addition to being one of the oldest continuously inhabited cities in the world, Damascus is a major...

, Syria

Syria

Syria , officially the Syrian Arab Republic , is a country in Western Asia, bordering Lebanon and the Mediterranean Sea to the West, Turkey to the north, Iraq to the east, Jordan to the south, and Israel to the southwest....

, at the exit of the Umayyad Mosque

Umayyad Mosque

The Umayyad Mosque, also known as the Great Mosque of Damascus or formerly the Basilica of Saint John the Baptist , is located in the old city of Damascus, is one of the largest and oldest mosques in the world...

 in the 12th century during the reign of Nur ad-Din Zangi.

Construction

There is a full description of the clock in the treatise Ktab 'Amal al-sa'at wa-l-amal biha (On the Construction of Clocks and their Use) written by Ridwan b. al Saati in 1203. This treatise describes the reconstruction by Ridwan of the water clock which was built by his father, Muhammad al-Saati, in the reign of Nur al-Din Mahmud b. Zanki in Damascus (reigned 1154–74). "The clock-face consisted of wall of timber about 4.23 metres wide and 2.78 metres high. In this screen was a row of doors, at either end of which was the figure of a falcon. During the day a small crescent moved at constant speed in front of the doors and at every hour a door rotated to reveal a different colour, the falcons leant forward, discharged pellets on to cymbals and resumed their upright positions. Above the doors a zodiac circle rotated at constant speed. Above this was a semicircle of twelve circular holes. During the night one of these holes became fully illuminated every hour. The clock was operated by the "Archimedes" water machinery and the motion transmitted to the activating mechanisms by pulley and rope systems."

Repairs

In 1203, al-Sa'ati's son Ridwan wrote a treatise on how he had been tasked to repair the clock his father had built, after others had failed.

Reconstruction

A full-size reconstruction of the clock can be seen in the Nationaal Beiaard- en Natuurmuseum Asten in the Netherlands.

External links

• Abdel Aziz al-Jaraki, "When Ridhwan al-Sa’ati Anteceded Big Ben by More than Six Centuries", 2007 (Muslimheritage.com) http://www.muslimheritage.com/topics/default.cfm?ArticleID=685
• Nationaal Beiaard- en Natuurmuseum Asten http://www.instapinternet.nl/0/139/files/Engels68833.pdf