Zhang Heng (張衡)

Born	78 Nanyang, China
Died	139 Luoyang, China
Residence	Luoyang
Field	Astronomy, Mathematics, Seismology, Hydraulics, Geography, Ethnography, Mechanical engineering, Calendrical science, Metaphysics, Poetry
Known for	Seismometer, Hydraulic-powered Armillary sphere, pi calculation, shi (poetry), Universe model, lunar eclipse and solar eclipse theory
Religion	Confucianism

For other uses, see Zhang Heng (disambiguation).

This is a Chinese name; the family name is Zhang.

Zhang Heng (張衡, Pinyin: Zhāng Héng, Wade-Giles: Chang Heng) (78 – 139 AD) was an astronomer, mathematician, inventor, geographer, artist, poet, statesman, and literary scholar of the Eastern Han Dynasty in ancient China. He had extensive knowledge of mechanics and gears, applying this knowledge to several of his known inventions. According to historian Joseph Needham, Zhang Heng was noted in his day for being able to "make three wheels rotate as if they were one (neng ling san lun du zhuan ye)".^[1] He is best known for his invention of the world's first water-powered armillary sphere to represent astronomical observation,^[2] and the world's first seismometer device, which discerned the cardinal direction of earthquakes from incredibly far distances.^[2][3][4] In the realm of early science, he is often compared by historians to his contemporaries in ancient Greece and ancient Rome. Image File history File links Zhang_Heng. ... For other uses, see number 78. ... Nanyang might be: Nanyang, Henan, (南阳) a city in the Peoples Republic of China. ... Events Births Deaths Zhang Heng, Chinese mathematician Categories: 139 ... Luoyang (Simplified Chinese: ; Traditional Chinese: ; pinyin: ) is a prefecture-level city in western Henan province, Peoples Republic of China. ... Luoyang (Simplified Chinese: ; Traditional Chinese: ; pinyin: ) is a prefecture-level city in western Henan province, Peoples Republic of China. ... A giant Hubble mosaic of the Crab Nebula, a supernova remnant Astronomy is the science of celestial objects (such as stars, planets, comets, and galaxies) and phenomena that originate outside the Earths atmosphere (such as auroras and cosmic background radiation). ... Euclid, Greek mathematician, 3rd century BC, as imagined by by Raphael in this detail from The School of Athens. ... Seismology (from the Greek seismos = earthquake and logos = word) is the scientific study of earthquakes and the propagation of elastic waves through the Earth. ... Table of Hydraulics and Hydrostatics, from the 1728 Cyclopaedia. ... Ethnography (from the Greek ethnos = people and graphein = writing) refers to the genre of writing that presents varying degrees of qualitative and quantitative descriptions of human social phenomena, based on fieldwork. ... Mechanical engineering is an engineering discipline that involves the application of principles of physics for analysis, design, manufacturing, and maintenance of mechanical systems. ... A page from the Hindu calendar 1871-72. ... Plato and Aristotle (right), by Raphael (Stanza della Segnatura, Rome). ... The Chinese poem Quatrain on Heavenly Mountain by Emperor Gaozong (Song Dynasty) Poetry (from the Greek , poiesis, making or creating) is a form of art in which language is used for its aesthetic qualities in addition to, or in lieu of, its ostensible meaning. ... Seismometers (in Greek seismos = earthquake and metero = measure) are used by seismologists to measure and record the size and force of seismic waves. ... Table of Hydraulics and Hydrostatics, from the 1728 Cyclopaedia. ... Armillary sphere An armillary sphere (variations known as a spherical astrolabe, armilla, or armil) is a model of the celestial sphere, invented by the ancient Greek Eratosthenes in 255 BC. Its name comes from the Latin armilla (circle, bracelet), since it has a skeleton made of graduated metal circles linking... When a circles diameter is 1, its circumference is Ï€. The mathematical constant Ï€ is an irrational real number, approximately equal to 3. ... Shi (è©©) is the Chinese word for poem; it can also be used to mean Chinese poetry other than lyrics, or (most commonly) the classical form of poetry developed in the late Han dynasty and which reached its zenith in the Tang dynasty. ... The shape of the Universe is an informal name for a subject of investigation within physical cosmology. ... Time lapse movie of the 3 March 2007 lunar eclipse A lunar eclipse occurs whenever the Moon passes through some portion of the Earths shadow. ... Photo taken during the 1999 eclipse. ... Wenmiao Temple, a Confucian Temple in Wuwei, Gansu Confucian temple in Kaohsiung, Republic of China (Taiwan). ... Zhang Heng can refer to: Zhang Heng, an ancient astronomer and mathematician Chang Heng, lunar crater named after him Zhang Heng, a fictional character from Water Margin This is a disambiguation page: a list of articles associated with the same title. ... This article or section does not adequately cite its references or sources. ... A Chinese surname, family name (Chinese: ; pinyin: ) or clan name (氏; pinyin: shì), is one of the hundreds or thousands of family names that have been historically used by Han Chinese and Sinicized Chinese ethnic groups in mainland China, Taiwan, and among overseas Chinese communities. ... Zhang (Traditional Chinese: 張, Simplified Chinese: 张, pinyin: Zhāng, Wade-Giles: Chang, Yale: Jeung, Jyutping: Zoeng1, Hong Kong Government: Cheung) is among the most common Chinese surnames. ... Hanyu Pinyin (Simplified Chinese: ; Traditional Chinese: ; pinyin: ), commonly called Pinyin, is the most common variant of Standard Mandarin romanization system in use. ... Wade-Giles, sometimes abbreviated Wade, is a Romanization (phonetic notation and transliteration) system for the Chinese language based on Mandarin. ... For other uses, see number 78. ... Events Births Deaths Zhang Heng, Chinese mathematician Categories: 139 ... Look up AD, ad-, and ad in Wiktionary, the free dictionary. ... An astronomer or astrophysicist is a person whose area of interest is astronomy or astrophysics. ... Leonhard Euler, one of the greatest mathematicians of all time A mathematician is a person whose primary area of study and research is the field of mathematics. ... For other uses, see Inventor (disambiguation). ... A geographer is a crazy psycho whose area of study is geocrap, the pseudoscientific study of Earths physical environment and human habitat and the study of boring students to death. ... The definition of an artist is wide-ranging and covers a broad spectrum of activities to do with creating art, practising the arts and/or demonstrating an art. ... The poor poet A poet is a person who writes poetry. ... Statesman is a respectful term used to refer to politicians, and other notable figures of state. ... Literature is literally an acquaintance with letters as in the first sense given in the Oxford English Dictionary (from the Latin littera meaning an individual written character (letter)). The term has, however, generally come to identify a collection of texts. ... The Han Dynasty (Traditional Chinese characters: 漢朝, Simplified Chinese characters: 汉朝, pinyin Hàncháo 202 BC - AD 220) followed the Qin Dynasty and preceded the Three Kingdoms in China. ... Mechanics (Greek ) is the branch of physics concerned with the behaviour of physical bodies when subjected to forces or displacements, and the subsequent effect of the bodies on their environment. ... Joseph Terence Montgomery Needham (December 9, 1900 – March 24, 1995) was a British biochemist and pre-eminent authority on the history of Chinese science. ... Armillary sphere An armillary sphere (variations known as a spherical astrolabe, armilla, or armil) is a model of the celestial sphere, invented by the ancient Greek Eratosthenes in 255 BC. Its name comes from the Latin armilla (circle, bracelet), since it has a skeleton made of graduated metal circles linking... Seismometers (in Greek seismos = earthquake and metero = measure) are used by seismologists to measure and record the size and force of seismic waves. ... This article or section does not cite its references or sources. ... An earthquake is the result from the sudden release of stored energy in the Earths crust that creates seismic waves. ... The Temple to Athena, the Parthenon Ancient Greece is a period in Greek history that lasted for around three thousand years. ... Ancient Rome was a civilization that grew from a small agricultural community founded on the Italian Peninsula circa the 9th century BC to a massive empire straddling the Mediterranean Sea. ...

Life

Born in what is now Nanyang, Henan, Zhang Heng was an accomplished writer at twelve. At sixteen, he left home to pursue his study in the capital cities. He spent at least ten years of his youth in literature studies and writing. He published several well recognized literary writings, and was admired for his straightforward style and natural poetic ability. In a poem criticizing the previous Western Han Dynasty, Zhang Heng once wrote: Nanyang might be: Nanyang, Henan, (南阳) a city in the Peoples Republic of China. ... Henan (Chinese: 河南; Hanyu Pinyin: ; Wade-Giles: Ho-nan), is a province of the Peoples Republic of China, located in the central part of the country. ...

Those who won this territory were strong;

Those who depended on it endured.

When a stream is long, its water is not easily exhausted.

When roots are deep, they do not rot easily.

Therefore, as extravagance and ostentation were given free reign,

The odour became pungent and increasingly fulsome ^[5]

Before his work in astronomy, mathematics, and technological invention, Zhang was a famed and notable literary author of poetry. Xiao Tong (501-531) immortalized several of Zhang's works in his anthology of literature, Wen xuan. Rhapsodies (fu 賦) include "Western Metropolis Rhapsody" 西京賦 (WX 2.36), "Eastern Metropolis Rhapsody" 東京賦 (WX 3.51), "Southern Capital Rhapsody" 南都賦 (WX 4.68), "Rhapsody on Contemplating the Mystery" 思玄賦 (WX 15.213), and "Rhapsody on Returning to the Fields" 歸田賦 (WX 15.222).^[6] The latter fu is an especially interesting piece, being very short compared to his other, mainly long epedeictic fu, and possessing a lyrical quality and refinement beyond its time. A set of four short lyric poems shi 詩, entitled "Lyric Poems on Four Sorrows" 四愁詩, is also included with Zhang's preface (WX 29.414). This set constitutes some of the earliest heptasyllabic shi Chinese poetry written. Zhang Heng's Four Stanzas of Sorrow is the first known seven-syllabic poem from China: Xiao Tong (è•­çµ±) (501-531), courtesy name Deshi (å¾·æ–½), formally Crown Prince Zhaoming (昭明太子, literally the accomplished and understanding crown prince), later further posthumously honored as Emperor Zhaoming (昭明皇帝), was a crown prince of the Chinese dynasty Liang Dynasty. ... Events Qi He Di succeeds Qo Dong Hun Hou as ruler of the Chinese Qi Dynasty Pope Symmachus is accused of various crimes, but claims that the secular rulers have no authority over him. ... Events End of the reign of Northern Wei Chang Guang Wang, ruler of the Chinese Northern Wei Dynasty. ... Fu (賦) is a Chinese literary form that combines prose and poetry, sometimes called rhymed prose. ... Fu (賦) is a Chinese literary form that combines prose and poetry, sometimes called rhymed prose. ... Shi (è©©) is the Chinese word for poem; it can also be used to mean Chinese poetry other than lyrics, or (most commonly) the classical form of poetry developed in the late Han dynasty and which reached its zenith in the Tang dynasty. ... Shi (è©©) is the Chinese word for poem; it can also be used to mean Chinese poetry other than lyrics, or (most commonly) the classical form of poetry developed in the late Han dynasty and which reached its zenith in the Tang dynasty. ... Quatrain on Heavenly Mountain by Emperor Gaozong Hand-painted Chinese New Years duilian (對聯 couplet), a by-product of Chinese poetry, pasted on the sides of doors leading to peoples homes, at Lijiang City, Yunnan Poetry is the most highly regarded literary genre in ancient China. ...

In Taishan stays my dear sweetheart,

But Liangfu keeps us long apart;

Looking east, I find tears start.

She gives me a sword to my delight;

A jade I give her as requite.

I'm at a loss as she is out of sight;

Why should I trouble myself all night?^[7]

His long lyrical poems also revealed a great amount of information on urban layout and basic geography, with his rhapsody "Sir Based-On-Nothing" providing details on terrain, palaces, hunting parks, markets, and prominent buildings of Chang'an.^[6] He also wrote about the various love affairs of the emperor, not satisfied with the imperial harem, going out into the city incognito to seek out prostitutes and sing-song girls. This was seen as a general criticism of present Eastern Han emperors and their imperial favorites, guised in the criticism of earlier Western Han emperors.^[8] The focus of Zhang's writing on specific places, its terrain, society, people, and their customs could also be seen as early attempts of ethnographic categorization.^[9] With his Reply to Criticism, Zhang Heng was also an early writer and proponent of the Chinese literary genre 'shelun', or 'hypothetical discourse', where the author creates a written dialogue between himself and an imaginary person (or they may be a real person of his entourage or association), and where the other poses questions to the author on how to lead a successful life.^[10] Ethnography (from the Greek ethnos = nation and graphe = writing) refers to the qualitative description of human social phenomena, based on months or years of fieldwork. ...

Zhang Heng began his studies in astronomy at the age of thirty, and began publishing his works in astronomy and mathematics. In 116, at the age of thirty-eight, Zhang became a government official for the court of Emperor An of Han. Zhang took on several positions since then, becoming the chief astrologer for the Han court. In his humble Confucian sensibility, Zhang respectfully declined many promotions that were offered to him that would have greatly advanced his career. Zhang eventually accepted the promoted position of President of the Imperial Chancellory. However, the 3rd century Chinese philosopher and poet Fu Xuan once lamented in an essay of his over the fact that Zhang Heng was never placed in the Ministry of Works. Writing highly of Zhang and the 3rd century mechanical engineer Ma Jun, Fu Xuan wrote: Events Roman Emperor Trajan completes his invasion of Parthia by capturing the cities of Seleucia, Ctesiphon and Susa, marking the high-water mark of the Roman Empires eastern expansion. ... Emperor An of Han, ch. ... An astrologer practices one or more forms of astrology. ... Confucianism (儒家 Pinyin: rújiā The School of the Scholars), sometimes translated as the School of Literati, is an East Asian ethical, religious and philosophical system originally developed from the teachings of Confucius. ... // Overview Events 212: Constitutio Antoniniana grants citizenship to all free Roman men 212-216: Baths of Caracalla 230-232: Sassanid dynasty of Persia launches a war to reconquer lost lands in the Roman east 235-284: Crisis of the Third Century shakes Roman Empire 250-538: Kofun era, the first... A philosopher is a person who thinks deeply regarding people, society, the world, and/or the universe. ... Fu Xuan (pinyin; Fu Hsüan, Wade-Giles; 217-278) was a Chinese poet of the Western Jin Dynasty. ... Look up engineer in Wiktionary, the free dictionary. ... Ma Jun a certain officer serving under Wei that oversaw the construction of Chong Huas palace under the orders of Cao Rui. ...

...neither of them was ever an official of the Ministry of Works, and their ingenuity did not benefit the world. When (authorities) employ personnel with no regard to special talent, and having heard of genius neglect even to test it - is this not hateful and disastrous? ^[11]

Zhang was given great honors in life and in death. In honor of his achievements in science and technology, Cui Zi-yu wrote a memorial inscription on the burial stele of Zhang Heng that stated:

His mathematical computations exhausted (the riddles of) the heavens and the earth. His inventions were comparable even to those of the Author of Change. The excellence of his talent and the splendour of his art were one with those of the gods.^[12]

Achievements in science and technology

In terms of invention and discovery, Zhang Heng was a prolific and revolutionary inventor and astronomical scientist for his age.

Astronomy, mathematics, and calendrical studies

With his astronomical finds and theories, Zhang was a pioneer of his day. In his publication of 120 AD called Ling Xian (靈憲, Mystical Laws, a summary of astronomical theories at the time), he approximated pi as 730/232 (or approx 3.1466), yet the later 3rd century Chinese mathematician Liu Hui would more accurately approximate pi. In one of his formulae for spherical volume calculation, he also used pi as the square root of 10 (or approx 3.162).^[13] Zhang Heng theorized that the universe was like an egg with the stars on the shell and the Earth as the yolk.^[4] This was similar to the Western geocentric model before the coming of Galileo Galilei. Although it was the ancient Warring States Chinese astronomers Shi Shen and Gan De who would compile the world's first star catalogue, Zhang nonetheless catalogued 2500 stars alone and recognized over 100 constellations. In relative comparison, this star catalogue featured many more positions for the stars than the Greek astronomer Hipparchus, who catalogued roughly 800 stars in his work of the 2nd century BC. In 123 Zhang Heng corrected the Chinese calendar to harmonize more accurately with the timing of the seasons, according to the finds of his astronomical observations. Like his contemporary, the philosopher Wang Chong, Zhang Heng also wrote of astronomical phenomena, such as the solar eclipse and lunar eclipse. In the Ling Xian, he wrote (Wade-Giles spelling): When a circles diameter is 1, its circumference is Ï€. The mathematical constant Ï€ is an irrational real number, approximately equal to 3. ... A possible likeness of Liu Hui on japanpostage stamp This is a Chinese name; the family name is 劉 (Liu) Liu Hui 劉徽 was a Chinese mathematician who lived in the 200s in the Wei Kingdom. ... Early printed rendition of the Ptolemaic system. ... KDFSAJFKASJDKFJASDKLJFDKLASJFLKJASKLFJLAKSJFLKSJALFKJSKLJFto the Sun-centered solar system which Galileo supported. ... Shi Shen (Chinese: ; Wade-Giles: Shih Shen, fl. ... This article or section is not written in the formal tone expected of an encyclopedia article. ... In astronomy, many stars are referred to simply by catalogue numbers. ... Hipparchus. ... Roman Emperor Hadrians villa at Tivoli was built. ... A page from the Hindu calendar 1871-72. ... Wang Chung (27 – 97 C.E.) (Traditional Chinese: 王充; Simplified Chinese: 王充; pinyin: Wáng Chōng) was a Chinese philosopher during the Han Dynasty who developed a rational, secular, naturalistic, and mechanistic account of the world and of human beings. ... Photo taken during the 1999 eclipse. ... Time lapse movie of the 3 March 2007 lunar eclipse A lunar eclipse occurs whenever the Moon passes through some portion of the Earths shadow. ...

The sun is like fire and the moon like water. The fire gives out light and the water reflects it. Thus the moon's brightness is produced from the radiance of the sun, and the moon's darkness is due to (the light of) the sun being obstructed. The side which faces the sun is fully lit, and the side which is away from it is dark. The planets (as well as the moon) have the nature of water and reflect light. The light pouring forth from the sun does not always reach the moon owing to the obstruction of the earth itself—this is called 'an-hsü', a lunar eclipse. When (a similar effect) happens with a planet (we call it) an occulation (hsing wei); when the moon passes across (the sun's path) then there is a solar eclipse (shih).^[14]

The water-powered armillary sphere

A modern replica of a Ming Dynasty era armillary sphere, found at the Beijing Ancient Observatory.

Zhang Heng is the first known person in history to apply hydraulic-run motive power (ie. by employing a clepsydra and waterwheel) to rotate the astronomical insturment of the armillary sphere.^[15][16] The Greek astronomer Eratosthenes invented the first armillary sphere in 255 BC, while the Chinese armillary sphere was developed in earnest by 52 BC, due to the adding of a permanently-fixed equatorial ring by the astronomer Geng Shouchang.^[17] In 84 AD the astronomers Fu An and Jia Kui added the ecliptic ring, and finally Zhang Heng added the horizon and meridian rings to the armillary sphere by 125 AD.^[17] Zhang described this invention in his written work Lou Shui Zhuan Hun Tian Yi Chi (Apparatus for Rotating an Armillary Sphere by Clepsydra Water) of 125 AD, and besides being one of the most impressive inventions of his day, it would influence later Chinese horologists in making waterclocks that employed complex gears (leading to the discovery of the escapement mechanism by the 8th century). The historian Joseph Needham states: Image File history File linksMetadata No higher resolution available. ... Image File history File linksMetadata No higher resolution available. ... For other uses, see Ming. ... Beijing (Chinese: 北京; pinyin: BÄ›ijÄ«ng; IPA: ;  ), a metropolis in northern China, is the capital of the Peoples Republic of China (PRC). ... Hydraulics is a branch of science and engineering concerned with the use of liquids to perform mechanical tasks. ... Clepsydra may refer to An ancient type of clock: see Clepsydra (clock) An invertebrate: see Clepsydra (animal) This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... An overshot water wheel standing 42 feet high powers the Old Mill at Berry College in Rome, Georgia A water wheel (also waterwheel, Norse mill, Persian wheel or noria) is a hydropower system; a system for extracting power from a flow of water. ... Armillary sphere An armillary sphere (variations known as a spherical astrolabe, armilla, or armil) is a model of the celestial sphere, invented by the ancient Greek Eratosthenes in 255 BC. Its name comes from the Latin armilla (circle, bracelet), since it has a skeleton made of graduated metal circles linking... Eratosthenes (Greek ; 276 BC - 194 BC) was a Greek mathematician, geographer and astronomer. ... Horology is the science and study of timekeeping devices. ... A water clock or clepsydra is a device for measuring time by letting water regularly flow out of a container usually by a tiny aperture. ... A simple escapement. ... Joseph Terence Montgomery Needham (December 9, 1900 – March 24, 1995) was a British biochemist and pre-eminent authority on the history of Chinese science. ...

What were the factors leading to the first escapement clock in China? The chief tradition leading to Yi Xing (+725 (AD)) was of course the succession of 'pre-clocks' which had started with Chang Heng (Zhang Heng) about +125 (AD). Reason has been given for believing that these applied power to the slow turning movement of computational armillary spheres and celestial globes by means of a water-wheel using clepsydra drip, which intermittently exerted the force of a lug to act on the teeth of a wheel on a polar-axis shaft. Chang Heng in his turn had composed this arrangement by uniting the armillary rings of his predecessors into the equatorial armillary sphere, and combining it with the principles of the water-mills and hydraulic trip-hammers which had become so widespread in Chinese culture in the previous century.^[18] Yi Xing (Yi-xing) (一行) (683 – 727) was a Chinese astronomer and buddhist monk of the Tang Dynasty. ... An overshot water wheel standing 42 feet high powers the Old Mill at Berry College in Rome, Georgia A water wheel is a hydropower system; a machine for extracting power from the flow of water. ... This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... A watermill is a machine constructed by connecting a water wheel to a pair of millstones. ... A triphammer is a massive power hammer, usually raised by a cam and then released to fall under the force of gravity. ...

Indeed, the Chinese tradition of hydraulic engineering was not initiated by Zhang in any sense, as it spanned back as far as the mid Zhou Dynasty (c. 6th century BC), with figures such as Sunshu Ao and Ximen Bao. In the contemporary age of Zhang Heng, there were those such as Du Shi (c. 31 AD), who was the first to apply the motive power of waterwheels to a mechanical device that operated bellows of the blast furnace to smelt cast iron. Still, Zhang's water-powered armillary sphere was a marvel of his day. As noted before, Zhang Heng provided a valuable description of his water-powered armillary sphere in the Lou Shui Zhuan Hun Tian Yi Chi treatise of 125. In it, Zhang states: Boundaries of the Western Zhou Dynasty (1050 - 771 BC) in China The Zhou Dynasty (Chinese: ; pinyin: ; Wade-Giles: Chou Ch`ao; 1122 BC to 256 BC (ref) followed the Shang (Yin) Dynasty and preceded the Qin Dynasty in China. ... Sunshu Ao (孫叔敖) was an ancient Chinese court minister serving the administration of Duke Zhuang of Chu during the reign of King Ding of Zhou (606 BC-586 BC), during the Eastern Zhou Dynasty. ... Ximen Bao (西門豹) was an ancient Chinese government minister and court advisor to Marquis Wen of Wei (文侯) (445 BC-396 BC) during the Warring States (481 BC-221 BC) period of China. ... Du Shi (Wade-Giles: Tu Shih, active 1st century AD) was a governmental Prefect of Nanyang in 31 AD and a mechanical engineer of the Eastern Han Dynasty in ancient China. ... Hand bellows The bellows is a device for delivering pressured air in a controlled quantity to a controlled location. ... Blast furnace in Sestao, Spain. ... Cast iron usually refers to grey cast iron, but can mean any of a group of iron-based alloys containing more than 2% carbon (alloys with less carbon are carbon steel by definition). ...

The equatorial ring goes around the belly of the armillary sphere 91 and 5/19 (degrees) away from the pole. The circle of the ecliptic also goes round the belly of the instrument at an angle of 24 (degrees) with the equator. Thus at the summer solstice the ecliptic is 67 (degrees) and a fraction away from the pole, while at the winter solstice it is 115 (degrees) and a fraction away. Hence (the points) where the ecliptic and the equator intersect should give the north polar distances of the spring and autumn equinoxes. But now (it has been recorded that) the spring equinox is 90 and 1/4 (degrees) away from the pole, and the autumn equinox is 92 and 1/4 (degrees) away. The former figure is adopted only because it agrees with the (results obtained by the) method of measuring solstitial sun shadows as embodied in the Xia (dynasty) calendar.^[19] The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ... World map showing the equator in red In tourist areas, the equator is often marked on the sides of roads The equator marked as it crosses Ilhéu das Rolas, in São Tomé and Príncipe. ... Illumination of Earth by the sun on the northern hemisphere summer solstice The summer solstice is an astronomical term regarding the position of the sun in relation to the celestial equator. ... Illumination of Earth by Sun on the day of the northern hemisphere winter solstice Illumination of Earth by Sun on the day of the southern hemisphere winter solstice In astronomy, the winter solstice is the moment when the earth is at a point in its orbit where one hemisphere is... Illumination of the Earth by the Sun on the day of equinox, (ignoring twilight). ...

In his treatise on the water-driven armillary sphere, Zhang Heng also provided valuable information on the Chinese clepsydra clock of his day, showing that the Chinese had invented the inflow clepsydra (as opposed to the earlier outflow clepsydra in late Zhou Dynasty China). In Zhang's description, he writes of a 'jade dragon's neck', which in later times meant a siphon,^[20] and wrote of the floats and indicator-rods of the inflow clepsydra: Boundaries of the Western Zhou Dynasty (1050 - 771 BC) in China The Zhou Dynasty (Chinese: ; pinyin: ; Wade-Giles: Chou Ch`ao; 1122 BC to 256 BC (ref) followed the Shang (Yin) Dynasty and preceded the Qin Dynasty in China. ... siphon principle A siphon (also spelled syphon) is a continuous tube that allows liquid to drain from a reservoir through an intermediate point that is higher than the reservoir, the up-slope flow being driven only by hydrostatic pressure without any need for pumping. ...

Bronze Vessels are made and placed one above the other at different levels; they are filled with pure water. Each has at the botttom a small opening in the form of a 'jade dragon's neck'. The water dripping (from above) enters two inflow receivers (alternately), the left one being for the night and the right one for the day. On the covers of each (inflow receiver) there are small cast statuettes in gilt bronze; the left (night) one is an immortal and the right (day) one is a policeman. These figures guide the indicator-rod (lit. arrow) with their left hands, and indicate the graduations on it with their right hands, thus giving the time.^[20] A gilded Tibetan Vajrasattva Gilding is the art of applying metal leaf (most commonly gold or silver leaf) to a surface. ...

A modern replica of Zhang Heng's seismometer, the Houfeng Didong Yi.

The water-powered armillary sphere of Zhang Heng would have profound effects upon Chinese astronomy and mechanical engineering in later generations. With Zhang Heng's complex use of gears and ingenious model, he would greatly influence later astronomers and engineers such as Yi Xing, Zhang Sixun, Su Song, Shen Kuo, and many others. A replica of an ancient Chinese Siesmograph from Eastern Han Dynasty (25-220 CE) This picture was taken in July 2004 from an exhibition at Chabot Space & Science Center in Oakland California. ... A replica of an ancient Chinese Siesmograph from Eastern Han Dynasty (25-220 CE) This picture was taken in July 2004 from an exhibition at Chabot Space & Science Center in Oakland California. ... Seismometers (in Greek seismos = earthquake and metero = measure) are used by seismologists to measure and record the size and force of seismic waves. ... Yi Xing (Yi-xing) (一行) (683 – 727) was a Chinese astronomer and buddhist monk of the Tang Dynasty. ... An artists interpretation of the astronomical clock tower of Su Song (1020-1101) Zhang Sixun (Chinese: ; pinyin: ; Wade-Giles: chang ssu hsün) was a 10th century Chinese astronomer and engineer during the Song Dynasty (960-1279 AD). ... Su Song 蘇頌 (1020 – 1101), style Zirong 子容, was a Chinese engineer. ... This is a Chinese name; the family name is Shen Shen Kuo or Shen Kua (Chinese: ; pinyin: ) (1031–1095 AD) was a polymath Chinese scientist of the Song Dynasty (960–1279 AD). ...

Zhang's seismograph

In 132, Zhang Heng presented to the Han court what many historians consider his most impressive invention. Zhang Heng invented the first seismometer, called Houfeng Didong Yi (lit. instrument for measuring the seasonal winds and the movements of the Earth), for determining the exact direction of tremors and earthquakes.^[16] According to the Book of Later Han, his copper-made urn-shaped device, with swinging inverted pendulum inside, was able to detect the direction of an earthquake from hundreds of miles/kilometers away.^[21] This was essential for the Han government in sending quick aid and relief to regions devastated by this natural disaster.^[21][3] Later Chinese of subsequent periods were able to reinvent Zhang's seismograph, including the 6th century mathematician Xindu Fang of the Northern Qi Dynasty,^[22] and the astronomer and mathematician Lin Xiao-gong of the Sui Dynasty (581–618).^[23] On June 13, 2005, modern Chinese seismologists announced that they had successfully created a replica of the instrument ^[24] Events The messianic, charismatic leader Simon bar Kokhba starts a war of liberation against the Romans, which is crushed by emperor Hadrian. ... Seismometers (in Greek seismos = earthquake and metero = measure) are used by seismologists to measure and record the size and force of seismic waves. ... An earthquake is the result from the sudden release of stored energy in the Earths crust that creates seismic waves. ... The Book of Later Han (Chinese:后汉书) is one of the official Chinese historical works which was compiled by Fan Ye in the 5th century, using a number of earlier histories and documents as sources. ... Simple gravity pendulum assumes no air resistance and no friction of/at the nail/screw. ... The Northern Qi Dynasty was one of the Northern dynasties of Chinese history and ruled northern China from 550 to 577. ... The Sui Dynasty (Chinese: ; pinyin: ; 581-619[1]) followed the Southern and Northern Dynasties and preceded the Tang Dynasty in China. ... Events The Sui Dynasty replaces the Northern Zhou Dynasty, the last of the Northern Dynasties in China. ... Events End of the Sui Dynasty and beginning of the Tang Dynasty in China. ... June 13 is the 164th day of the year in the Gregorian calendar (165th in leap years), with 201 days remaining. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... Seismology (from the Greek seismos = earthquake and logos = word) is the scientific study of earthquakes and the movement of waves through the Earth. ...

Odometer and South Pointing Chariot

Zhang Heng is often accredited with the invention of the first odometer (also pronounced hodometer) device in China, an achievement alongside earlier contemporaries Archimedes and Heron of Alexandria from the Hellenized West. An odometer is a device which mechanically or electronically measures the distance traveled by an operated vehicle (found standard in modern automobiles), and was a mechanical device used by the Roman and Han-Chinese empires in roughly the same time frame. By the 3rd century, the Chinese had termed the device as the 'ji li gu che', or 'li-recording drum carriage' (Note: the modern measurement of li = 500 m/1640 ft).^[25] Ancient Chinese texts tell of the mechanical carriage's functions, and as one li is traversed, a mechanical-driven wooden figure strikes a drum, and when ten li is traversed, another wooden figure would strike a gong or a bell with its mechanical-operated arm.^[25] However, there is evidence to suggest that the invention of the odometer was a gradual process in Han Dynasty China that centered around the huang men court people (ie. eunuchs, palace officials, attendants and familiars, actors, acrobats, etc.) that would follow the musical procession of the royal 'drum-chariot'.^[26] There is speculation that some time in the 1st century BC, during the Western Han Dynasty, the beating of drums and gongs were mechanically-driven by working automatically off the rotation of the road-wheels.^[26] This might have actually been the design of one Loxia Hong (c. 110 BC), yet by at least 125 AD the mechanical odometer carriage was already known, depicted in a mural of the Xiao Tang Shan Tomb.^[26] A modern non-digital odometer A Smiths speedometer from the 1920s showing odometer and trip meter An odometer is a device used for indicating distance traveled by an automobile or other vehicle. ... Archimedes (Greek: c. ... Heros aeolipile Hero (or Heron) of Alexandria (c. ... The term Hellenistic (established by the German historian Johann Gustav Droysen) in the history of the ancient world is used to refer to the shift from a culture dominated by ethnic Greeks, however scattered geographically, to a culture dominated by Greek-speakers of whatever ethnicity, and from the political dominance... Car redirects here. ... The li (里 lǐ) is a Chinese unit of distance, until recently usually considered to be about 576 metres, but is now standardised at a half a kilometre or 500 metres (547 yards). ...

The South Pointing Chariot is another mechanical contraption accredited to Zhang Heng. It is a non-magnetic compass-vehicle shaped in the form of a wheeled chariot, and functioning off of differential gears. The mechanical device of the differential provides equal amount of torque to wheels rotating at different speeds. This device allowed a fixed wooden figurine (in the shape of a Chinese state minister) to constantly point in the southern direction, hence the name of the device. The Song Shu (c. 500 AD) records that Zhang Heng re-invented it from its earliest model found in the Zhou Dynasty period, but the violent collapse of the Han Dynasty unfortunately did not allow it to be preserved. Whether the ancient passage of this book on Zhang Heng is valid or not, Ma Jun (200-265 AD) of the following century was successful in creating it.^[27] South Pointing Chariot (replica) Supposedly invented sometime around 2600BC in China by the Yellow Emperor Huang Di, the South Pointing Chariot (Zhi Nan Ju 指南車) is widely regarded as the most complex geared mechanism of the ancient Chinese civilization. ... In an automobile and other four-wheeled vehicles, a differential is a device, usually consisting of gears, that allows each of the driving wheels to rotate at different speeds, while supplying equal torque to each of them. ... Torque applied via an adjustable end wrench Relationship between force, torque, and momentum vectors in a rotating system In physics, torque (or often called a moment) can informally be thought of as rotational force or angular force which causes a change in rotational motion. ... Ma Jun a certain officer serving under Wei that oversaw the construction of Chong Huas palace under the orders of Cao Rui. ... For other uses, see number 200. ... Events Wei Yuandi abdicates, end of the China. ...

A closer look at Zhang's seismograph

From the earliest times, the Chinese were concerned with the destructive force of earthquakes. It was recorded in Sima Qian's Shiji (Records of the Grand Historian) that in 780 BC an earthquake had been devastative enough to divert the course of three different rivers.^[28] The ancient Chinese did not understand the cause of earthquakes as being the shift of tectonic plates in the earth's crust. Chinese of the ancient Zhou Dynasty (1050 BC–256 BC) explained the natural phenomenon in terms of disturbances with cosmic Yin and yang, along with the heavens' displeasure with acts committed (or the common peoples' grievances ignored) by the current ruling dynasty.^[28] These theories were ultimately derived from the ancient text of the I Ching (Book of Changes), in its fifty-first hexagram zhen.^[29] There were other early theories about earthquakes by those in ancient Greece; Anaxagoras believed that earthquakes derived from excess water towards the surface crust of the earth bursting below into the hollows of the earth; Democritus believed it was because of the saturation of the earth with water; Anaximenes believed it was because of massive parts of the earth falling into the cavernous hollows due to drying; Aristotle believed it was caused by instability of vapor (pneuma) caused by the drying of the moist earth by the warmth of sun rays.^[29] Sima Qian Si Ma Qian (司馬遷) (c. ... The tectonic plates of the world were mapped in the second half of the 20th century. ... Boundaries of the Western Zhou Dynasty (1050 - 771 BC) in China The Zhou Dynasty (Chinese: ; pinyin: ; Wade-Giles: Chou Ch`ao; 1122 BC to 256 BC (ref) followed the Shang (Yin) Dynasty and preceded the Qin Dynasty in China. ... (Redirected from 1050 BC) Centuries: 12th century BC - 11th century BC - 10th century BC Decades: 1100s BC 1090s BC 1080s BC 1070s BC 1060s BC - 1050s BC - 1040s BC 1030s BC 1020s BC 1010s BC 1000s BC Events and Trends 1053 BC - Death of Zhou kang wang, King of the... Centuries: 4th century BC - 3rd century BC - 2nd century BC Decades: 300s BC 290s BC 280s BC 270s BC 260s BC - 250s BC - 240s BC 230s BC 220s BC 210s BC 200s BC Years: 261 BC 260 BC 259 BC 258 BC 257 BC - 256 BC - 255 BC 254 BC... Taijitu, the traditional symbol representing the forces of yin and yang The dual concepts of yin and yang – or the single concept yin-yang – originate in ancient Chinese philosophy and metaphysics, which describe two primal opposing but complementary principles said to be found in all non-static objects and processes... Alternative meaning: I Ching (monk) The I Ching (Traditional Chinese: 易經, pinyin y jīng; Cantonese IPA: jɪk6gɪŋ1; Cantonese Jyutping: jik6ging1; alternative romanizations include I Jing, Yi Ching, Yi King) is the oldest of the Chinese classic texts. ... Alternative meaning: I Ching (monk) The I Ching (Traditional Chinese: 易經, pinyin yì jīng; Cantonese IPA: jɪk6gɪŋ1; Cantonese Jyutping: jik6ging1; alternative romanizations include I Jing, Yi Ching, Yi King) is the oldest of the Chinese classic texts. ... The Temple to Athena, the Parthenon Ancient Greece is a period in Greek history that lasted for around three thousand years. ... Anaxagoras Anaxagoras (Greek: Αναξαγόρας, c. ... ‎ Democritus (Greek: ) was a pre-Socratic Greek philosopher (born at Abdera in Thrace around 460 BC). ... Anaximenes was the name of several notable people in ancient Greece. ... Aristotle (Greek: AristotélÄ“s) (384 BC – 322 BC) was a Greek philosopher, a student of Plato and teacher of Alexander the Great. ...

Going against the grain of the early theories proposed by his fellow Chinese and contemporary Greeks, Zhang Heng believed earthquakes to be caused by air, writing:

The chief cause of earthquake is air, an element naturally swift and shifting from place to place. As long as it is not stirred, but lurks in a vacant space, it reposes innocently, giving no trouble to objects around it. But any cause coming upon it from without rouses it, or compresses it, and drives it into a narrow space...and when opportunity of escape is cut off, then 'With deep murmur of the Mountain it roars around the barriers', which after long battering it dislodges and tosses on high, growing more fierce the stronger the obstacle with which it has contended.^[30]

In any case, Zhang was responsible for detecting the cardinal direction of this natural phenomenon. In the Hou Han Shu (Book of Later Han, compiled by Fan Ye in the 5th century), there is a detailed description of the device in his biography, which states: The Book of Later Han (Chinese: 後漢書; pinyin: ) is one of the official Chinese historical works which was compiled by Fan Ye (Traditional Chinese: 范瞱; Simplified Chinese: 范晔; 398-445), using a number of earlier histories and documents as sources. ... The Book of Later Han (Chinese:后汉书) is one of the official Chinese historical works which was compiled by Fan Ye in the 5th century, using a number of earlier histories and documents as sources. ... Fan Ye was born on October 23, 1986 in Hebei, China. ...

In the first year of the Yang-Chia reign period (+132 (AD)) Chang Heng also invented an 'earthquake weathercock' (i.e. a seismograph). It consisted of a vessel of fine cast bronze, resembling a wine-jar, and having a diameter of eight chhih [Note: eight chi = roughly 6 ft). It had a domed cover, and the outer surface was ornamented with antique seal-characters and designs of mountains, tortoises, birds, and animals. Inside there was a central column capable of lateral displacement along tracks in the eight directions, and so arranged (that it would operate) a closing and opening mechanism.^[31]

Outside the vessel there were eight dragon heads, each one holding a bronze ball in its mouth, while round the base there sat eight (corresponding) toads, with their mouths open, ready to receive any ball which the dragons might drop. The toothed machinery and ingenious constructions were all hidden inside the vessel, and the cover fitted down closely all round without any crevice. When an earthquake occurred the dragon mechanism of the vessel was caused to vibrate so that a ball was vomited out of a dragon-mouth and caught by the toad underneath. At the same instant a sharp sound was made which called the attention of the observers.^[31]

Now although the mechanism of one dragon was released, the seven (other) heads did not move, and by following the (azimuthal) direction (of the dragon which had been set in motion), one knew (the direction) from which the earthquake (shock) had come (lit. where the earthquake was). When this was verified by the facts there was (found) an almost miraculous agreement (i.e. between the observations made with the apparatus and the news of what had actually happened). Nothing like this had ever been heard of before since the earliest records of the Shu (Jing).^[31]

On one occasion one of the dragons let fall a ball from its mouth though no perceptible shock could be felt. All the scholars at the capital were astonished at this strange effect occurring without any evidence (of an earthquake to cause it). But several days later a messenger arrived bringing news of an earthquake in Long-Xi (Gansu) (Note: which was 400 miles away to the north-west). Upon this everyone admitted the mysterious power of the instrument. Thenceforward it became the duty of the officials of the Bureau of Astronomy and Calendar to record the directions from which earthquakes came.^[32] Gansu (Simplified Chinese: 甘肃; Traditional Chinese: 甘肅; Hanyu Pinyin: ; Wade-Giles: Kan-su, Kansu, or Kan-suh) is a province located in the northwest of the Peoples Republic of China. ...

Furthermore, Zhang Heng's seismograph device incorporated the following in order to function properly:

• Eight mobile arms radiating in as many directions and each connected with cranks which are provided with catch mechanisms at the periphery.
• Any one of the cranks which raises a dragon head and so releases a ball is thus at the same time caught and held, thus immobilising the instrument.
• A crank
• A right-angle lever for raising the dragon's head
• A vertical pin passing through a slot in the crank
• An arm of the pendulum
• The pendulum
• A catch
• A pivot on a projection
• A sling suspending the pendulum
• Attachment of the sling
• A horizontal bar supporting the pendulum
• The lower jaw of the dragon supporting the ball.^[33]

Named in his honour

• lunar crater Chang Heng
• asteroid 1802 Zhang Heng
• mineral Zhanghengite

He also features as a Great Engineer in the PC game Civilization IV. Chang Heng is a lunar crater that is located on the Moons far side. ... Zhanghengite is a mineral consisting of 80% copper and zinc, 10% iron with the balance made up of chromium and aluminium. ... Sid Meiers Civilization IV (or Civilization IV) is a turn-based strategy computer game released in 2005 and developed by lead designer Soren Johnson under the direction of Sid Meier and Meiers studio Firaxis Games. ...

See Also

• Astronomy
• Seismology
• List of Chinese people
• List of Chinese writers
• List of scientists
• List of astronomers
• List of mechanical engineers

A giant Hubble mosaic of the Crab Nebula, a supernova remnant Astronomy is the science of celestial objects (such as stars, planets, comets, and galaxies) and phenomena that originate outside the Earths atmosphere (such as auroras and cosmic background radiation). ... Seismology (from the Greek seismos = earthquake and logos = word) is the scientific study of earthquakes and the propagation of elastic waves through the Earth. ... It has been suggested that this article be split into multiple articles accessible from a disambiguation page. ... // 屈原 Qu Yuan (340 ? -278 ? BC) 宋玉 Song Yu (3rd century BC) 司馬遷 Sima Qian (145- ? BC) 司馬相如 Sima Xiangru (179-117 BC) 班固 Ban Gu (32-92) 張衡 Zhang Heng (78-139) 曹操 Cao Cao (155-220) 曹丕 Cao Pi (187-226) 曹植 Cao Zhi (192-232) 嵇康 Xi Kang (223-262) 陸機 Luigi Jigi (261-303) 陶淵明 Tao Yuanming (365... This page contains links to lists of scientists. ... Famous astronomers and astrophysicists include: Contents: Top - 0–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z [edit] A Marc Aaronson (USA, 1950 – 1987) George Ogden Abell (USA, 1927 – 1983) Antonio Abetti... This is a list of mechanical engineers, notable people who were trained in or practiced mechanical engineering, nuclear engineering, etc. ...

Notes

This article contains Chinese text. Without proper rendering support, you may see question marks, boxes, or other symbols instead of Chinese characters.

Image File history File links Zhongwen. ... 漢字 / 汉字 Chinese character in Hanzi, Kanji, Hanja, Hán Tự. Red in Simplified Chinese. ...

References

• Declercq, Dominik (1998). Writings Against the State: Political Rhetorics in Third and Fourth Century China. Leiden: Koninklijke Brill NV.
• Huang, Ray (1997). China: A Macro History. New York: An East Gate Book, M. E. SHARPE Inc.
• Lewis, Mark Edward (2006). The Construction of Space in Early China. New York: State University of New York Press.
• Morton, W. Scott and Charlton M. Lewis (2005). China: It's History and Culture. New York: McGraw-Hill, Inc.
• Needham, Joseph (1986). Science and Civilization in China: Volume 3, Mathematics and the Sciences of the Heavens and the Earth. Taipei: Caves Books, Ltd.
• Needham, Joseph (1986). Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 2: Mechanical Engineering. Taipei: Caves Books, Ltd.
• Wilson, Robin J. (2001). Stamping Through Mathematics. New York: Springer-Verlag New York, Inc.
• Wright, David Curtis (2001) The History of China. Westport: Greenwood Press.

External Links

• A Biography of Zhang Heng