<P> Since Yi Xing's clock was a water clock, it was affected by temperature variations . That problem was solved in 976 by Zhang Sixun by replacing the water with mercury, which remains liquid down to − 39 ° C (− 38 ° F). Zhang implemented the changes into his clock tower, which was about 10 metres (33 ft) tall, with escapements to keep the clock turning and bells to signal every quarter - hour . Another noteworthy clock, the elaborate Cosmic Engine, was built by Su Song, in 1088 . It was about the size of Zhang's tower, but had an automatically rotating armillary sphere--also called a celestial globe--from which the positions of the stars could be observed . It also featured five panels with mannequins ringing gongs or bells, and tablets showing the time of day, or other special times . Furthermore, it featured the first known endless power - transmitting chain drive in horology . Originally built in the capital of Kaifeng, it was dismantled by the Jin army and sent to the capital of Yanjing (now Beijing), where they were unable to put it back together . As a result, Su Song's son Su Xie was ordered to build a replica . </P> <P> The clock towers built by Zhang Sixun and Su Song, in the 10th and 11th centuries, respectively, also incorporated a striking clock mechanism, the use of clock jacks to sound the hours . A striking clock outside of China was the Jayrun Water Clock, at the Umayyad Mosque in Damascus, Syria, which struck once every hour . It was constructed by Muhammad al - Sa'ati in the 12th century, and later described by his son Ridwan ibn al - Sa'ati, in his On the Construction of Clocks and their Use (1203), when repairing the clock . In 1235, an early monumental water - powered alarm clock that "announced the appointed hours of prayer and the time both by day and by night" was completed in the entrance hall of the Mustansiriya Madrasah in Baghdad . </P> <P> The first geared clock was invented in the 11th century by the Arab engineer Ibn Khalaf al - Muradi in Islamic Iberia; it was a water clock that employed a complex gear train mechanism, including both segmental and epicyclic gearing, capable of transmitting high torque . The clock was unrivalled in its use of sophisticated complex gearing, until the mechanical clocks of the mid-14th century . Al - Muradi's clock also employed the use of mercury in its hydraulic linkages, which could function mechanical automata . Al - Muradi's work was known to scholars working under Alfonso X of Castile, hence the mechanism may have played a role in the development of the European mechanical clocks . Other monumental water clocks constructed by medieval Muslim engineers also employed complex gear trains and arrays of automata . Like the earlier Greeks and Chinese, Arab engineers at the time also developed a liquid - driven escapement mechanism which they employed in some of their water clocks . Heavy floats were used as weights and a constant - head system was used as an escapement mechanism, which was present in the hydraulic controls they used to make heavy floats descend at a slow and steady rate . </P> <P> A mercury clock, described in the Libros del saber de Astronomia, a Spanish work from 1277 consisting of translations and paraphrases of Arabic works, is sometimes quoted as evidence for Muslim knowledge of a mechanical clock . However, the device was actually a compartmented cylindrical water clock, which the Jewish author of the relevant section, Rabbi Isaac, constructed using principles described by a philosopher named "Iran", identified with Heron of Alexandria (fl . 1st century AD), on how heavy objects may be lifted . </P>

Who invented the first mechanical clock in 1300
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