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Zhang Sixun (fl. 10th century) was a Chinese astronomer
Astronomer

An astronomer is a scientist who studies Celestial body such as planets, stars, and Galaxy.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using physical laws....
 and military engineer
Military engineer

A military engineer is primarily responsible for the design and construction of offensive, defensive, and logistical structures for warfare. Other duties include the layout, placement, maintenance and dismantling of defensive land mine and the clearing of enemy minefields and the construction and destruction of bridges....
 from Bazhong, Sichuan
Bazhong

Bazhong is a prefecture-level city in north-eastern Sichuan province....
 during the early Song Dynasty
Song Dynasty

The Song Dynasty was a ruling Chinese dynasty in China between 960–1279 AD; it succeeded the Five Dynasties and Ten Kingdoms Period, and was followed by the Yuan Dynasty....
 (960-1279 AD). He is credited with creating an armillary sphere
Armillary sphere

An armillary sphere is a model of the celestial sphere....
 for his astronomical clock tower
Clock tower

A clock tower is a tower built with one or more clock Clock face. The clock tower is usually part of a church or municipal building such as a town hall, but many clock towers are free-standing....
 that employed the use of liquid mercury
Mercury (element)

Mercury , also called quicksilver or hydrargyrum , is a chemical element with the symbol Hg and atomic number 80. A heavy, silvery d-block metal, mercury is one of six elements that are liquid at or near room temperature and pressure....
 (dripped periodically from a clepsydra
Clepsydra

Clepsydra may refer to*Clepsydra , the Greek word for water clock.* Clepsydra Geyser in the Lower Geyser Basin of Yellowstone*Clepsydra , a genus of protists....
 clock). The liquid mercury filled scoops of the waterwheel would rotate and thus provide the effect of an escapement
Escapement

In mechanical watches and clocks, an escapement is a device which converts continuous rotational motion into an Oscillatory or back and forth motion....
 mechanism in clockworks and allow the astronomical armillary sphere to rotate as needed.






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Zhang Sixun (fl. 10th century) was a Chinese astronomer
Astronomer

An astronomer is a scientist who studies Celestial body such as planets, stars, and Galaxy.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using physical laws....
 and military engineer
Military engineer

A military engineer is primarily responsible for the design and construction of offensive, defensive, and logistical structures for warfare. Other duties include the layout, placement, maintenance and dismantling of defensive land mine and the clearing of enemy minefields and the construction and destruction of bridges....
 from Bazhong, Sichuan
Bazhong

Bazhong is a prefecture-level city in north-eastern Sichuan province....
 during the early Song Dynasty
Song Dynasty

The Song Dynasty was a ruling Chinese dynasty in China between 960–1279 AD; it succeeded the Five Dynasties and Ten Kingdoms Period, and was followed by the Yuan Dynasty....
 (960-1279 AD). He is credited with creating an armillary sphere
Armillary sphere

An armillary sphere is a model of the celestial sphere....
 for his astronomical clock tower
Clock tower

A clock tower is a tower built with one or more clock Clock face. The clock tower is usually part of a church or municipal building such as a town hall, but many clock towers are free-standing....
 that employed the use of liquid mercury
Mercury (element)

Mercury , also called quicksilver or hydrargyrum , is a chemical element with the symbol Hg and atomic number 80. A heavy, silvery d-block metal, mercury is one of six elements that are liquid at or near room temperature and pressure....
 (dripped periodically from a clepsydra
Clepsydra

Clepsydra may refer to*Clepsydra , the Greek word for water clock.* Clepsydra Geyser in the Lower Geyser Basin of Yellowstone*Clepsydra , a genus of protists....
 clock). The liquid mercury filled scoops of the waterwheel would rotate and thus provide the effect of an escapement
Escapement

In mechanical watches and clocks, an escapement is a device which converts continuous rotational motion into an Oscillatory or back and forth motion....
 mechanism in clockworks and allow the astronomical armillary sphere to rotate as needed. He designed the model for his armillary sphere in 976 and completed the creation of it in 977.

Life and works


Zhang Sixun, although innovative, built upon the efforts of those before him. It was the Han Dynasty
Han Dynasty

The Han Dynasty followed the Qin Dynasty and preceded the Three Kingdoms in China. The Han Dynasty was ruled by the family known as the Liu clan who had peasant origins....
 era scientist and engineer Zhang Heng
Zhang Heng

Zhang Heng was an Chinese astronomy, Chinese mathematics, List of Chinese inventions, Chinese geography, History of cartography#China, Chinese art, Chinese poetry, Government of the Han Dynasty, and Chinese literature from Nanyang, Henan, Henan, and lived during the Eastern Han Dynasty of China....
 (78-139 AD) who invented the first hydraulic-powered (ie. with waterwheel and clepsydra) armillary sphere. In addition, it was the Tang Dynasty
Tang Dynasty

The Tang Dynasty was an Dynasties in Chinese history preceded by the Sui Dynasty and followed by the Five Dynasties and Ten Kingdoms Period. It was founded by the Li family, who seized power during the decline and collapse of the Sui Empire....
 era Buddhist monk
Monk

A Monk is a person who practices religious asceticism, the unconditioning of mind and body in favor of the realization of one's true nature, and does so living either alone or with any number of like-minded people, whilst always maintaining some degree of physical separation from those not sharing the same purpose....
 and engineer Yi Xing
Yi Xing

Yi Xing , born Zhang Sui , was a China astronomer, mathematician, mechanical engineering, and Buddhist monk of the Tang Dynasty . His astronomical celestial globe was the first to feature a clockwork escapement mechanism, the first in a long tradition of Chinese astronomical clock....
 (683-727 AD) who invented the first hydraulic-powered armillary sphere that incorporated the escapement
Escapement

In mechanical watches and clocks, an escapement is a device which converts continuous rotational motion into an Oscillatory or back and forth motion....
 mechanism. Yet Zhang Sixun applied some innovative ideas of his own in order for his hydraulic-powered armillary sphere to function. His astronomical armillary sphere and clock was much like that of the later statesman Su Song
Su Song

Su Song was a renowned Chinese people Scholar-bureaucrat, Chinese astronomy, History of cartography#China, horology, Traditional Chinese medicine, mineralogy, zoology, botany, mechanics and Chinese architecture, Chinese poetry, antiquarian, and Foreign relations of Imperial China of the Song Dynasty ....
 (1020-1101 AD), incorporating the scoop-bearing driving-wheel and gearing, together with 19 clock jacks to report and sound the hours. His device also employed the use of liquid mercury
Mercury (element)

Mercury , also called quicksilver or hydrargyrum , is a chemical element with the symbol Hg and atomic number 80. A heavy, silvery d-block metal, mercury is one of six elements that are liquid at or near room temperature and pressure....
 in the closed circuit of the clepsydra and waterwheel instead of water, because water would freeze easily during winter, while mercury could assure smooth and continual function and time-keeping during the cold season. Later Ming Dynasty
Ming Dynasty

The Ming Dynasty , or Empire of the Great Ming , was the ruling Dynasties in Chinese history of China from 1368 to 1644, following the collapse of the Mongol-led Yuan Dynasty....
 clocks had the same concern in mind when they employed the use of falling sand grains to push the wheel drive. The later Su Song wrote that after Zhang's death, no one could replicate what he had achieved, much like with Su Song himself and his astronomical clock tower
Clock tower

A clock tower is a tower built with one or more clock Clock face. The clock tower is usually part of a church or municipal building such as a town hall, but many clock towers are free-standing....
 after his own death.

Historical texts

The later Song Dynasty historical text of the Song Shi
Twenty-Four Histories

The Twenty-Four Histories is a collection of China historical books covering a period of history from 3000 BC to the Ming Dynasty in the 17th century....
 (compiled in 1345 AD) records Zhang's work (Wade-Giles
Wade-Giles

Wade-Giles , sometimes abbreviated Wade, is a Romanization system for the Mandarin Chinese language used in Beijing. It developed from a system produced by Thomas Francis Wade in the mid-19th century, and reached settled form with Herbert Giles' Chinese language-English language dictionary of 1892....
 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 ordered artisans of the Imperial Workshops to construct it within the Palace. On a kuei-mao day in the first month of the 4th year (+979) the elaborate machine was completed, and the emperor caused it to be placed under the eastern drum-tower of the Wen-Ming Hall.


The system of Chang Ssu-Hsun was as follows: they built a tower of three storeys (totalling) more than ten feet in height, within which was concealed all the machinery. It was round (at the top to symbolize) the heavens, and square (at the bottom to symbolize) the earth. Below there was set up the lower wheel (ti lun), lower shaft (ti chu), and the framework base (ti tsu). There were also horizontal wheels (heng lun), (vertical) wheels fixed sideways (tshe lun), and slanting wheels (hsieh lun, i.e. oblique gearing); bearings for fixing them in place (ting shen kuan), a central coupling device (chung kuan) and a smaller coupling device (hsiao kuan)(i.e. the escapement); with a main transmission shaft (thien chu). Seven jacks rang bells on the left, struck a large bell on the right, and beat a drum in the middle to indicate clearly the passing of the quarter(-hours).


Each day and night (each 24 hours) the machinery made one complete revolution, and the seven luminaries moved their positions around the ecliptic. Twelve other wooden jacks were also made to come out at each of the (double-)hours, one after the other, bearing tablets indicating the time. The lengths of the days and nights were determined by the (varying) numbers of the quarters (passing in light and darkness). At the upper part of the machinery there were the top piece (thien ting), upper gear(-wheel or -wheels)(thien ya), upper linking device (thien kuan; another part of the escapement), upper (anti-recoil) ratchet pin (thien chih), celestial (ladder?) gear-box (thien tho), upper framework beam carrying bearings (thien shu), and the upper connecting-chain (thien thiao). There were also (on a celestial globe?) the 365 degrees (to show the movement of) the sun, moon, and five planets; as well as the Purple Palace (north polar region), the lunar mansions (hsiu) in their ranks, and the Great Bear, together with the equator and the ecliptic which indicated how the changes of the advance and regression of heat and cold depend upon the measured motions of the sun.


The motive power of the clock was water, according to the method which had come down form Chang Heng [Zhang Heng] in the Han Dynasty through I-Hsing [Yi Xing] and Liang Ling-tsan in the Khai-Yuan reign period (+713 to +741)(of the Thang). But the bronze and iron (of their clocks) had long gone to rust (thung thieh chien se) and could no longer move automatically. Moreover, as during winter the water partly froze and its flow was greatly reduced, the machinery lost its exactness, and there was no constancy between the hot and cold weather. Now, therefore, mercury was employed as a substitute, and there were no more errors...The images of the sun and moon were also attached high up (to the globe) and according to the old method they had been moved by human hand (each day), but now success was attained in having them move automatically. This was a marvellous thing. (Chang) Ssu-Hsun was considered the equal of the Thang clock-makers and was made Special Assistant in charge of the Armillary Sphere (Engine)(Ssu-Thien Hun I Chheng).


See also


  • List of Chinese people
    List of Chinese people

    The following is a list of famous Chinese language people.Note in Chinese names, the Chinese family name is typically placed first . For westernized names, the family name is placed last ....
  • Verge escapement
    Verge escapement

    The verge escapement is the earliest known type of mechanical escapement, the mechanism in a mechanical clock that controls its rate by advancing the gear train at regular intervals or 'ticks'....
  • History of science and technology in China
    History of science and technology in China

    The history of science and technology in China is both long and rich with many contributions to science and technology. In antiquity, independently of Greek philosophers and other civilizations, ancient China philosophers made significant advances in science, technology, mathematics, and astronomy....
  • Technology of the Song Dynasty
    Technology of the Song Dynasty

    The Song Dynasty provided some of the most significant technology advances in History of China, many of which came from talented statesmen drafted by the government through imperial examinations....
  • History of China
    History of China

    China civilization originated in various city-states along the Yellow River valley in the Neolithic era. The written history of China begins with the Shang Dynasty ....
  • Mechanical engineering
    Mechanical engineering

    Mechanical Engineering is an engineering discipline that involves the application of physics#branches of physics for analysis, design, manufacturing, and maintenance of machine....


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