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He invented a mechanized water clock with the Tantric monk and mathematician Yi Xing (Chinese: 一行; pinyin: Yī Xíng; Wade–Giles: I-Hsing). [1] [2] [3] It was actually an astronomical instrument that served as a clock, made of bronze in the capital of Chang'an in the 720s. It was described by a contemporary text this way:
Yi Xing also owed much to the scholarly followers of Ma Jun, who had employed horizontal jack-wheels and other mechanical toys worked by waterwheels. [4] The Daoist Li Lan was an expert at working with water clocks, creating steelyard balances for weighing water that was used in the tank of the clepsydra, [4] providing more inspiration for Yi Xing.
Yi Xing's device also had a mechanically timed bell that was struck automatically every year, and a drum that was struck automatically every quarter-hour; essentially, a striking clock. [24] Yi Xing's astronomical clock and water-powered armillary sphere became well known throughout the country, since students attempting to pass the imperial ...
The liquid in water clocks was liable to freezing, and had to be kept warm with torches, a problem that was solved in 976 by the Chinese astronomer and engineer Zhang Sixun. His invention—a considerable improvement on Yi Xing's clock—used mercury instead of water. Mercury is a liquid at room temperature, and freezes at −38.83 °C (−37.9 ...
The tower clock of Norwich Cathedral constructed c. 1273 (reference to a payment for a mechanical clock dated to this year) is the earliest such large clock known. The clock has not survived. [ 95 ] The first clock known to strike regularly on the hour, a clock with a verge and foliot mechanism, is recorded in Milan in 1336. [ 96 ]
The famous clock tower that the Chinese polymath Su Song built by 1094 during the Song dynasty would employ Yi Xing's escapement with waterwheel scoops filled by clepsydra drip, and powered a crowning armillary sphere, a central celestial globe, and mechanically operated manikins that would exit mechanically opened doors of the clock tower at ...
The later Song dynasty historical text of the Song Shi (compiled in 1345 AD) records Zhang's work (Wade-Giles spelling): . At the beginning of the Thai-Phing Hsing-Kuo reign-period (+976) the Szechuanese Chang Ssu-Hsun [Zhang Sixun], a student in the Bureau of Astronomy, invented an astronomical clock (lit. armillary sphere, hun i) and presented the designs to the emperor Thai Tsung, who ...
His clocks of the period used a grasshopper escapement which malfunctioned if not driven continuously—even while the clock was being wound. In essence, the maintaining power consists of a disc between the driving drum of the clock and the great wheel. The drum drives the disc, and a spring attached to the disc drives the great wheel.