Zhang Sixun
Encyclopedia
Zhang Sixun was a Chinese astronomer
and military engineer
from Bazhong, Sichuan
during the early Song Dynasty
(960-1279 AD). He is credited with creating an armillary sphere
for his astronomical clock tower
that employed the use of liquid mercury
(dripped periodically from a clepsydra
clock). The liquid mercury filled scoops of the waterwheel would rotate and thus provide the effect of an escapement
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.
era scientist and engineer Zhang Heng
(78-139 AD) who invented the first hydraulic-powered (ie. with waterwheel and clepsydra) armillary sphere. In addition, it was the Tang Dynasty
era Buddhist monk
and engineer Yi Xing
(683-727 AD) who invented the first hydraulic-powered armillary sphere that incorporated the escapement
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
(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
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
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
after his own death.
(compiled in 1345 AD) records Zhang's work (Wade-Giles
spelling):
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.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...
and military engineer
Military engineer
In military science, engineering refers to the practice of designing, building, maintaining and dismantling military works, including offensive, defensive and logistical structures, to shape the physical operating environment in war...
from Bazhong, Sichuan
Bazhong
Bazhong is a prefecture-level city in north-eastern Sichuan province, People's Republic of China.-History:Bazhong was made a prefecture-level city in 1993. Its history, however, goes back much further. During the Xia and Shang Dynasties, it was purportedly a vassal territory of the Liang State. In...
during the early Song Dynasty
Song Dynasty
The Song Dynasty was a ruling dynasty in China between 960 and 1279; it succeeded the Five Dynasties and Ten Kingdoms Period, and was followed by the Yuan Dynasty. It was the first government in world history to issue banknotes or paper money, and the first Chinese government to establish a...
(960-1279 AD). He is credited with creating an armillary sphere
Armillary sphere
An armillary sphere is a model of objects in the sky , consisting of a spherical framework of rings, centred on Earth, that represent lines of celestial longitude and latitude and other astronomically important features such as the ecliptic...
for his astronomical clock tower
Clock tower
A clock tower is a tower specifically built with one or more clock faces. Clock towers can be either freestanding or part of a church or municipal building such as a town hall. Some clock towers are not true clock towers having had their clock faces added to an already existing building...
that employed the use of liquid mercury
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
(dripped periodically from a clepsydra
Clepsydra
Clepsydra may refer to:*Clepsydra , the Greek word for water clock. Also, in ancient Greece, a device for drawing liquids from vats too large to pour, which utilized the principles of air pressure to transport the liquid from one container to another.* Clepsydra Geyser in the Lower Geyser Basin of...
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 that transfers energy to the timekeeping element and enables counting the number of oscillations of the timekeeping element...
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 DynastyHan Dynasty
The Han Dynasty was the second imperial dynasty of China, preceded by the Qin Dynasty and succeeded by the Three Kingdoms . It was founded by the rebel leader Liu Bang, known posthumously as Emperor Gaozu of Han. It was briefly interrupted by the Xin Dynasty of the former regent Wang Mang...
era scientist and engineer Zhang Heng
Zhang Heng
Zhang Heng was a Chinese astronomer, mathematician, inventor, geographer, cartographer, artist, poet, statesman, and literary scholar from Nanyang, Henan. He lived during the Eastern Han Dynasty of China. He was educated in the capital cities of Luoyang and Chang'an, and began his career as a...
(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 imperial dynasty of China 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, living either alone or with any number of monks, while 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 Chinese astronomer, mathematician, mechanical engineer,and Buddhist monk of the Tang Dynasty...
(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 that transfers energy to the timekeeping element and enables counting the number of oscillations of the timekeeping element...
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 polymath who specialized himself as a statesman, astronomer, cartographer, horologist, pharmacologist, mineralogist, zoologist, botanist, mechanical and architectural engineer, poet, antiquarian, and ambassador of the Song Dynasty .Su Song was the engineer of a...
(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 is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
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, also Empire of the Great Ming, was the ruling dynasty of China from 1368 to 1644, following the collapse of the Mongol-led Yuan Dynasty. The Ming, "one of the greatest eras of orderly government and social stability in human history", was the last dynasty in China ruled by ethnic...
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 specifically built with one or more clock faces. Clock towers can be either freestanding or part of a church or municipal building such as a town hall. Some clock towers are not true clock towers having had their clock faces added to an already existing building...
after his own death.
Historical texts
The later Song Dynasty historical text of the Song ShiTwenty-Four Histories
The Twenty-Four Histories is a collection of Chinese historical books covering a period from 3000 BC to the Ming Dynasty in the 17th century. The whole set contains 3213 volumes and about 40 million words...
(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. It developed from a system produced by Thomas Wade during the mid-19th century , and was given completed form with Herbert Giles' Chinese–English dictionary of 1892.Wade–Giles was the most...
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
- Verge escapementVerge escapementThe 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'. Its origin is unknown. Verge escapements were used from the 14th century until about 1800 in clocks...
- History of science and technology in ChinaHistory of science and technology in ChinaThe history of science and technology in China is both long and rich with many contributions to science and technology. In antiquity, independently of other civilizations, ancient Chinese philosophers made significant advances in science, technology, mathematics, and astronomy...
- Technology of the Song DynastyTechnology of the Song DynastyThe Song Dynasty provided some of the most significant technological advances in Chinese history, many of which came from talented statesmen drafted by the government through imperial examinations....
- History of ChinaHistory of ChinaChinese civilization originated in various regional centers along both the Yellow River and the Yangtze River valleys in the Neolithic era, but the Yellow River is said to be the Cradle of Chinese Civilization. With thousands of years of continuous history, China is one of the world's oldest...
- Mechanical engineeringMechanical engineeringMechanical engineering is a discipline of engineering that applies the principles of physics and materials science for analysis, design, manufacturing, and maintenance of mechanical systems. It is the branch of engineering that involves the production and usage of heat and mechanical power for the...