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Translated by Chan Ying Kit Preface Technology is the backbone of a nation’s development, fundamental to social progress and economic prosperity. In global history, the technological advancement of China had taken the lead for a long period of time. The various technological achievements of ancient China had contributed significantly to world civilization. For more than 5,000 years, the diligent and intelligent Chinese people created a robust scientific civilization, leaving behind a number of achievements that warrant global attention. In astrology, Chinese ancestors invented the armillary sphere and the seismograph, as well as having devised several calendars. The Chinese had also invented the world’s earliest automated observatory and the water clock tower. In geography, Xuanzang wrote the worldrenowned Journey to the West, while Xu Xiake completed a monumental geological work, Journey of Xu Xiake. In the art of handicraft, the Chinese invented the arrow and bow, bronze, embroidery and silk. These inventions are pivotal in advancing world civilization. At the same time, China made tremendous progress in the study of physics, chemistry, m e d i c i n e , a r c h i t e c t u r e , t e x t i l e , p o t t e r y, shipbuilding and waterworks. The ostensible Four Great Inventions of the Chinese— gunpowder, compass, paper and printing—had promoted the advancement of world civilization by their widespread adoption and use. Technology creates as well as changes history. Science and technology have influenced productivity the most. Francis Bacon, an English philosopher who pioneered the scientific content_sciTech.indd 1 9/10/2012 5:59:25 PM method of empirical enquiry, wrote that "printing, gunpowder and the compass…whence have followed innumerable changes, in so much that no empire, no sect, no star seems to have exerted greater power and influence in human affairs than these mechanical discoveries.” Understanding the history of Chinese science and technology is integral to inheriting the benefits from these inventions. The great achievements of the ancient Chinese had proven that the Chinese race has enormous creativity. We could inherit this spirit of innovation and active exploration, reviving past Chinese glories. To realise this ambition, we have to study the ancient Chinese inventions and learn from them and their creators, reliving the imagination and ingenuity of the Chinese people. This book adopts a new layout to present five millennia of technological development in Chinese history. We have divided the book into the sections of Astronomy, Geography, Hydraulic Engineering, Architecture, Agriculture, Mathematics, Physics and Chemistry, Medicine and Handicraft in a bid to condense and recapitulate Chinese civilization in a concise yet comprehensive manner, providing readers with a “delectable and wholesome” treat to Chinese history in pictorial representations. It is our hope that the book would serve as an entertaining and educational compendium of Chinese scientific and technological accomplishments from time immemorial. content_sciTech.indd 2 9/10/2012 5:59:25 PM Contents Astronomy 天文历法 Xia Xiao Zheng 《夏小正》 2 Gan Shi Star Manual 《甘石星经》 4 Zhoubi Classic in Calculation 《周髀算经》 6 Taichu Li 《太初历》 8 Zhang Heng 张衡 10 Zhang Heng’s Seismometer 候风地动仪 12 Qianxiang Li 《乾象历》 14 Great Brilliance Calendar (Daming Li) 《大明历》 16 Zhang Zixin’s Three Discoveries Huangji Calendar Yixing's Technological Achievements Treatise on Astrology of the Kaiyuan Era Tower for Water-Powered Sphere & Globe Twelve Qi Calendar 张子信 《皇极历》 一行 18 20 22 《开元占经》 24 水运仪象台 26 《十二气历》 28 Wang Xun 王恂 30 Simplified Armillary Sphere, and Works and Days Calendar 仰仪和《授时历》 32 Wang Xichan 王锡阐 34 Geography 地理探索 The Classic of the Mountains and Seas The Compass 《山海经》 指南针 38 40 Yu Gong Geographical Map 《禹贡地域图》 42 A Record of Buddhist Kingdoms 《佛国记》 44 Commentary on the Waterways Classic 《水经注》 46 Great Tang Records on the Western 《大唐西域记》 Regions Dream Pool Essays (Mengxi Bitan) The Voyages of Zheng He content_sciTech.indd 3 48 《梦溪笔谈》 50 郑和下西洋 52 9/10/2012 5:59:25 PM The Travelogues of Xu Xiake 《徐霞客游记》 54 T h e F a m o u s G e o g r a p h e r Ya n g Shoujing 杨守敬 56 Li Siguang, Famous Scientist and Geologist 李四光 58 Hydraulic Engineering 水利工程 Exploiting the Terrain for Flood Protection 大禹治水 Shaopei Dam 芍陂 Irrigation Canals from the Zhang River 引漳灌邺 into Ye 62 64 66 Dujiangyan Irrigation System 都江堰 68 Zhengguo Canal 郑国渠 70 Ling Canal 灵渠 72 Longshou Drain 龙首渠 74 Mystery of the Kan’er Wells 坎儿井之谜 76 Zhaozhou Bridge 赵州桥 78 Grand Canal 京杭大运河 80 Gezhou Dam 葛洲坝 82 Three Gorges Dam 三峡工程 84 Qufu Confucius Temple 曲阜孔庙 88 The Great Wall of China 长城 90 Yellow Crane Tower 黄鹤楼 92 Potala Palace 布达拉宫 94 Giant Wild Goose Pagoda 大雁塔 96 Architecture 建筑设计 Treatise on Architectural Methods 《营造法式》 98 Shanxi Ying County Wooden Pagoda 山西应县木塔 100 The Forbidden City 故宫 102 Zhuozheng Garden 拙政园 104 Suzhou Lingering Garden 苏州留园 106 Chengde Imperial Summer Villa 承德避暑山庄 108 Summer Palace 颐和园 110 content_sciTech.indd 4 9/10/2012 5:59:26 PM Agriculture 农学农具 Ma Jun 马钧 114 Substituting Land Method 代田法 116 Book of Fan Shen 《汜胜之书》 118 Siming Yueling 《四民月令》 120 Essential Methods of the Common 《齐民要术》 People 122 Essence of Tea Farming Plow Quyuanli Wang Zhen's Book of Agriculture Huang Daopo's Invention 《茶经》 124 曲辕犁 126 《王祯农书》 黄道婆 128 130 Nongzheng Quanshu 《农政全书》 132 Tiangong Kaiwu 《天工开物》 134 Yuan Longping 袁隆平 136 算筹 140 Mathematics 数学成就 The Counting-rods The Nine Chapters on Mathematical Art 《九章算术》 142 The World's First Precise Calculation of the Pi, π 圆周率 144 Mathematician Qin Jiushao 秦九韶 146 Southern Song Mathematician, Yang Hui 杨辉 148 Zhu Shijie and Jade Mirror of the Four 《四元玉鉴》 Unknowns 150 Pioneer of Contemporary Mathematics, Li Shanlan 李善兰 152 Hua Luogeng 华罗庚 154 Chen Jingrun 陈景润 156 content_sciTech.indd 5 9/10/2012 5:59:27 PM Physics & Chemistry 物理化学 《墨经》 160 Light-transmitting Mirror 透光镜 162 Invention of Hydraulic-Powered Blast Furnace 水排 164 Paper-making Technology 造纸术 166 Mystery around the Invention of Gunpowder 火药 168 Movable Type Printing 活字印刷术 170 Watertight Compartment 水密隔舱 172 Zhan Tianyou 詹天佑 174 Hou Debang, the Great Chemist 侯德榜 176 Qian Xuesen, the Famous Physicist 钱学森 178 Qiang Sanqiang 钱三强 180 Deng Jiaxian 邓稼先 182 Wang Xuan 王选 184 Acupuncture 针灸 188 Massage 推拿按摩 190 The Divine Physician Bian Que's Medical Contributions 扁鹊 192 Mo's Scripts Medicine 医学药物 Yellow Emperor's Inner Canon 《黄帝内经》 194 Divine Farmer's Materia Medica 《神农本草经》 196 Huo Tuo, the Surgical Pioneer 华佗 198 Treatise on Cold Pathogenic and Miscellaneous Diseases 《伤寒杂病论》 200 Canon of Acupuncture and Moxibustion 《针灸甲乙经》 202 The Pulse Classic 《脉经》 204 Handy Therapies for Emergencies 《肘后备急方》 206 Sun Simiao, the King of Medicine 孙思邈 208 Tang Materia Medica 《唐本草》 210 The World's First Forensic Book 《洗冤集录》 212 content_sciTech.indd 6 9/10/2012 5:59:27 PM Zhu Su, Prince of Medical Achievements 朱橚 214 Compendium of Materia Medica 《本草纲目》 216 Orthodoxy in Surgery 《外科正宗》 218 Wu Youxing's School of Pestilential Epidemics Correction of Errors in Medical Classics 吴有性 《医林改错》 220 222 Handicraft 手工制造 Revolution of the Artisans 土木工具 226 The Kite 风筝 228 The Records of Examination of Craftsman 《考工记》 230 Xuan Paper 宣纸 232 Su Embroidery 苏绣 234 The Invention of Pottery 陶器 236 Lacquer Ware 漆器 238 The Invention of Bronze Ware 青铜器 240 The Invention of Porecelain 瓷器 242 The Yongle Bell 永乐大钟 244 content_sciTech.indd 7 9/10/2012 5:59:29 PM Xia Xiao Zheng China’s Earliest Calendar X ia Xiao Zheng is China’s earliest work on phenology and agricultural almanac; the work was an important reference on climatic conditions and changes in the pre-Qin era. Xia Xiao Zheng scrolls Xia Xiao Zheng《夏小正》is one of the earliest documents in ancient China. It is also the earliest remaining almanac that adopts the Daylight Saving Time method of advancing time. The various terms that the book uses are simple and succinct, but the content remains extensive. Also, the book uses a 12-month system to record the phenology, weather, climate and important political events, especially the events that portrayed China as an agrarian society. The book shows that the crops that the pre-Qin Chinese had cultivated included cereals, fibrous plants, dyes and horticultural crops; other activities were rearing silkworms and livestock, fishing and hunting. Rearing of silkworms and horses was significant. The neutering of horses, the production of blue dye and the cultivation of Brassica, peaches and apricots are recorded in the book, constituting their first historical documentation. The most outstanding part of Xia Xiao Zheng is on phenology. Owing to agricultural needs of the time, the book records phenological information that determines the time or season most suitable for farming. The Chinese had used the book to document their agricultural activities conducted in different months. Most of the texts are arranged in lines of two to four characters. To record the change in climate, the book describes the palpable changes in plants and animals. In addition, the book uses terms from visible constellations such as Chen San (辰参)and Zhi Nü 织女 (Weaver Girl) for greater clarity. The book, however, lacks records of constellations for the months of November, December and February. Also, the concept of the four seasons and the 24 solar terms had not been established yet. Xia Xiao Zheng does not mention anything about handicraft; labour distribution at that time was not advanced. This also shows that Xia Xiao Zheng is a book or almanac of great antiquity. 2 Sci_Tec.indd FINAL.indd 2 9/10/2012 5:22:06 PM C H IN E S E S C IE N C E A N D TEC H N O LO G Y A Chinese traditional astrological chart Great debate has been raved on the completion of Xia Xiao Zheng. The general consensus is that it was completed in the Spring and Autumn Period. Before the Sui Dynasty, the book comprised only one chapter in Book of Rites of Dai 《大戴礼记》that Dai Dehui of Western Han had written. Later, the book emerged as an offprint and was published for the first time in Chronicles of Sui《隋书•经籍志》. From the Northern Song to the Qing Dynasty, more than 10 revisions of the book were made. Rumours had it that Yu of the Xia Dynasty “issued Xia Calendar to tributary states”. In Book of Rites, Confucius said, “I would like to experience the rites of Xia; it is the predecessor of Ji that I cannot analyse in depth. I have the Xia Calendar.” Zheng Xuanjian said, “For those who possess the Xia Calendar, there is a chapter entitled Xiao Zheng in the document.” In Historical Records of Xia 《史记•夏本纪》, Sima Qian wrote that Confucius had used Xia Calendar along with many other scholars. All these records confirm that Xia Xiao Zheng was used before the Spring and Autumn Period. C o n t e m p o r a r y s c h o l a r s X i a We i y i n g a n d F a n Chuyu argue that the scripts in Xia Xiao Zheng might have originated in the Shang or Zhou Dynasty. The other possibility is that Huaihai residents had compiled it before the Spring and Autumn Period. Xia Xiao Zheng contains vivid details about the legendary Xia Dynasty and provides important information for the analysis of ancient Chinese agricultural technology. The chapter Zhuan in Xia Xiao Zheng was written by the people of the Warring States Period. Regarding the regions that were referred to in Xia Xiao Zheng, Xia Weiying posits that the scripts clearly reflect the phenology of the Huaihai region. However, not all scholars hold his view. Dai’s Xia Xiao Zheng, compiled by Bo Songqing in the Song Dynasty Origin of the Weaver Girl The seventh lunar month is the time when summer gradually turns into autumn, so it was an important month on the calendar. The author of Xia Xiao Zheng went to great lengths to describe the celestial features of the seventh lunar month. Besides the movement of the Milky Way and the Big Dipper, the author also mentioned the Weaver Girl star. Nevertheless, on a starry sky, the Weaver Girl looks like any other star. Slightly brighter than the rest, it does not have any other unique features. Why did the ancient Chinese adore this star so much as to adorn it with a name and poignant legend? In the seventh month, the summer heat began to subside and the wind turned cold. At this time, ladies began to spin and weave, making winter clothes to prepare for cold autumn and harsh winter. This is when the Weaver Girl reached its apogee in the sky. On the ground, ladies manoeuvred the spinning wheel and sang under the starry sky. In the sky, the Weaver Girl shone brightly as the ladies weaved, and it became the celestial patron of the weaving ladies. 3 Sci_Tec.indd FINAL.indd 3 9/10/2012 5:22:07 PM Gan Shi Star Manual The World’s First Astronomical Book D uring the Eastern Zhou period, productivity levels rose rapidly, and astronomers achieved significant breakthroughs in their field. The Gan Shi Star Manual became the world’s first star-catalogue, contributing to the historical development of astronomical research in both China and the world. Statue of Gan De observing the stars China is one of the birthplaces of astronomy. To meet the needs of agricultural production and calendar-charting, the Chinese started to observe and record the stars and signs, using their observations and records to define directions, time and seasons. During the Eastern Zhou period, Gan De of the Chu state and Shi Shen of the Wei state conducted astronomical research and after years of observation, each produced a book that documented their findings. Gan De wrote the Tianwen Xingzhan《天文星占》, and Shi Shen, Tianwen《天文》; each book contained eight volumes. During the Han Dynasty, readers produced and circulated the books separately, until other writers collected excerpts from the two books and compiled them into the Gan Shi Star Manual《甘石星经》. Shi Shen devised a nomenclature different from that of Gan De for the constellations and stars that he had observed. Shi Shen’s nomenclature was to name a particular asterism (a pattern of stars on Earth’s night sky) and determine the number of stars that the asterism contained. Using Shi Shen’s method, a star was designated as “Asterism name plus Number”. During the Three Kingdoms period, Chen Zhuo consolidated the star charts of Gan De, Shi Shen and another astronomer Wu Xian and derived a total of 283 constellations and 1,464 stars from them, of which 146 constellations were recorded by Gan De; all the 1,464 fixed stars were marked in a star map in different colours. Later astronomers used the map to work out a star atlas and a celestial sphere. Gan De, therefore, contributed much to the naming of the constellations; he also measured and deduced the positions of the stars, but the results of his findings had been lost. Shi Shen made exceptional breakthroughs in studying the motion of Venus, Jupiter, Mercury, Mars and Saturn. He calculated that Jupiter is visible from Earth every 400 days 4 Sci_Tec.indd FINAL.indd 4 9/10/2012 5:22:09 PM C H IN E S E S C IE N C E A N D TEC H N O LO G Y (the synoptic period), deviating from the accurate time of 398.88 days by only 1.12 days. Shi Shen also discovered that the motion of Jupiter is not constant, and that Jupiter often strays from the ecliptic (the plane of Earth’s orbit around the Sun), reflecting superior standards in Chinese astronomy. In addition, Shi Shen determined the visible cycle of Mercury from Earth to be 136 days, deviating from the actual duration of 115 days; although the discrepancy is significant, Shi Shen understood the four stages of the motion of Mercury. Finally, Shi Shen was the first person to observe the retrograde motion of Mars, having calculated the visible cycle of Mars to be 410.780 days, close to the actual figure. Later generations called the compilations by Gan De and Shi Shen the Gan Shi Star Manual. The Gan Shi Star Manual was the world’s first star-catalogue that emerged before the Greek astronomer Hipparchus compiled his findings two centuries later. The Manual, however, was lost during the Song Dynasty, and fragments of which were found incorporated in the Kaiyuan Zhanjing《开元占经》 (The Kaiyuan Reign Treatise on Astrology and Astronomy). The Gan Shi Star Manual was, in fact, the first astronomical book in both China and the world. The book enjoyed a lasting heritage as a reference for determining the position and motion of the Sun, the Moon and the planets. In particular, Shi Shen’s star-catalogue was fundamental to the measurement of celestial bodies because it expresses the 28 lunar constellations in the ascensional differences of their respective stars as arranged along the equator from west to east, as well as the angle between the fixed star and the celestial pole. The star catalogue was a unique Chinese contribution to world astronomy because it adopted the equatorial coordinate system instead of the Western ecliptic coordinate system to mark the positions of fixed stars. Gan Shi Star Manual. Shi Shen Tianwen became known as Shi’s Star Manual after the Western Han Dynasty. Shi Shen Moon Crater Many annals, official records and astronomical books had referred to the Gan Shi Star Manual. To commemorate Shi Shen’s achievements, the crater Shi Shen on the Moon is named after him. The crater is the most notable feature on the Moon’s surface, located near the North Pole of the Moon, resting on the coordinates of 105 degrees east and 76 degrees north, and having an area of 350 sq km. 5 Sci_Tec.indd FINAL.indd 5 9/10/2012 5:22:10 PM Zhoubi Classic in Calculation China's First Astronomical Monograph T he Zhoubi Classic in Calculation (Zhoubi Suanjing) is the first Chinese book on astronomy to date, detailing the height of mountains and the area of land. The book features the size and distance of celestial bodies, as well as a proof of the Pythagorean Theorem, so it was crucial to the mathematical and scientific development of later generations. Zhoubi Suanjing Zhoubi Suanjing《周髀算经》is viewed as the best of the top 10 Chinese mathematical texts. Originally named Zhoubi, the book is China’s first canonical work on astronomy, dating from the Han Dynasty, although some historians argue that the book was produced earlier in the Zhou Dynasty and finalised in the Western Han Dynasty. Conventional wisdom decrees that the Zhoubi Suanjing is a mathematical text. The book, however, is actually an astronomical work that associates mathematical concepts with astronomical observations. To discuss the astronomical calendar and laws, the book records and narrates several mathematical concepts and knowledge, emphasising the Pythagorean Theorem, ratio measurement, and the computation of stellar orientation to explain the two concepts of the celestial sphere and the QuarterRemainder Calendar. The concept of the celestial sphere is included in the earliest Chinese cosmological theory. The theory proposes that Heaven is a spherical umbrella that covers the square Earth; Earth is like a chessboard, above which the Sun, the Moon and the stars move. Therefore, the theory is also known as the “Spherical Heaven and Square Earth” theory. Another precept of the theory is that the celestial bodies of the Sun, the Moon and the stars do not emerge and disappear; optical illusion results in their invisibility when they are afar and visibility when they are near. At the writing of the Zhoubi Suanjing, the celestial sphere theory became a complete and quantitative system of measuring standards, reflecting progress in Chinese cosmological understanding and astronomical development. Have you wondered, on a starry night, how high the sky is? Thousands of years ago, our human ancestors had pondered over the same question. The Zhoubi Suanjing records a tale in which the legendary Duke Zhou asked the 6 Sci_Tec.indd FINAL.indd 6 9/10/2012 5:22:10 PM C H IN E S E S C IE N C E A N D TEC H N O LO G Y mathematician Shang Zhou, “How high is the sky?” Shang Zhou replied, “Using the Pythagorean Theorem, we can calculate the height of the sky from Earth.” So, what is the Pythagorean Theorem? On a piece of paper, draw a rectangle of breadth 3 cm and length 4 cm. Next, draw a diagonal line across the shape and measure it; you would realise that the diagonal line is 5 cm long. The Pythagorean Theorem is in practice here, and it is also known as the Shang Zhou Theorem. Zhoubi Suanjing also records how our human ancestors used simple arithmetic to calculate the distance between Earth and the Sun: first, enact tall poles of 8 feet across the land and record the length of the pole shadow at noon; the records show that the one in Chang’an measures one foot six inch and that in a location that is 1 km south of Chang’an, it is one foot five inch; the records reveal that for every 1 km moved from Chang’an along the north-south axis, the shadow of the pole would differ by an inch. The experiment was done in summer and in winter, and ancient people calculated the distance between Earth and the Sun to be 100,000 li. Although the figure is a far cry from the actual distance of 149,500,000 km, the method that the Chinese had adopted was correct. Zhoubi Suanjing also writes about the square root and arithmetical progression, as well as the Quarter-Remainder Calendar, suggestive of the mathematical complexity and capacity of the Chinese. The Ten Mathematical Manuals The Ten Mathematical Manuals The Ten Mathematical Classics refer to ten mathematical books written over a span of a millennium from the Han to the Tang Dynasty. These books were assigned textbooks at the Imperial Academy of the Sui Dynasty. They are: 1. Zhoubi Classic in Calculation (Zhoubi Suanjing) 2. Nine Chapters on Mathematical Art (Jiuzhang Suanshu) 3. Sea Island Mathematical Manual (Haidao Suanjing) 4. Mathematical Manual of the Five Government Departments (Wucao Suanjing) 5. Mathematical Manual of Sunzi (Sunzi Suanjing) 6. Mathematical Manual of Xiahou Yang (Xiahou Yang Suanjing) 7. Mathematical Manual of Zhang Qiujian (Zhang Qiujian Suanjing) 8. Five Classics Mathematical Art (Wujing Suanshu) 9. Continuation of Ancient Mathematics (Jigu Suanjing) 10. The “Stitching” Method (Zhuishu) By the time the Song contemporaries compiled and printed the Ten Mathematical Manuals, The “Stitching” Method and Mathematical Manual of Xiahou Yang were already lost, so Shushu Jiyi replaced the former and Hanyan Suanshu, the latter, retaining the name Mathematical Manual of Xiahou Yang. 7 Sci_Tec.indd FINAL.indd 7 9/10/2012 5:22:10 PM Taichu Li Earliest and Most Complete Calendrical System T he formulation of the Taichu Li is a major achievement in the historical development of Chinese calendrical science, as well as in Chinese cosmological theory. The Taichu Li is China’s first and most comprehensive calendrical system of which adequate records are preserved, and it had been the most advanced system in the world at its inception. In the early years of the Western Han Dynasty, people used the Calendar of the Legendary Emperor Zhuanxu, known as Zhuanxu Li 《颛顼历》devised in the Qin era. Discrepancies between this calendar and astronomical occurrences, however, were already noticed, so Emperor Han Wudi accepted the counsel of Sima Qian and others to revise the calendrical system in 104 BC. The Emperor assigned his courtiers Gongsun Qing, Hu Sui and Sima Qian to recruit and lead more than 20 astronomers to devise a new calendrical system, and these astronomers included Deng Ping, Sima Ke, Hou Yijun, Tang Du, and Luo Xiahong (落下 闳). The imperial team possibly used apparatus and instruments, as well as hypotheses and inferences to propose 18 calendrical systems. After repeated debate, experimentations and analyses, the Emperor chose the system that Deng Ping and Luo Xiahong had proposed. The Emperor changed the name of his reign from Yuanfeng to Taichu, pronouncing that any year henceforth had 12 months, and that a year began in spring and ended in winter. The Taichu Li《太初历》is China’s first imperial enactment of a calendrical system. In the system, the tropical year is 365.2502 days and the synodic month is 29.53086 days. Instead of having the 10th month as the beginning month of the year, the system determines the first month to start the year. The system adopts the 24 solar terms that are suited for an agrarian China, resolving the discrepancies between the solar and the lunar cycles. Luo Xiahong’s Calendrical System Astronomers devised the Taichu Li based on astronomical data and statistics. After careful measurements and calibrations, they formulated the comprehensive system of the Taichu Li. The system conceives that the Sun circles Bronze statue of Luo Xiahong 8 Sci_Tec.indd FINAL.indd 8 9/10/2012 5:22:11 PM C H IN E S E S C IE N C E A N D TEC H N O LO G Y Earth, and Luo Xiahong’s system unifies the qualitative and the quantitative in setting the 10 basic cycles in his calendar: Huigui, Zhirun, Rishi, Ganzhi Year, Ganzhi Day, Jupiter, Mars, Saturn, Venus and Mercury. Innovations in Time Periodisation The Taichu Li defines the first month in spring as the start of a year, and has hence harmonised and unified time for annals, imperial reigns and agricultural production. It also determines the month without the zhongqi (中气) (midperiod; without the 12 or 24 solar terms) as the lunyue (闰 月) (leap month). The Taichu Li remained in use from the Western Han Dynasty to the late Ming period for almost two millennia. The new 24 fortnightly periods or solar terms have allowed the Chinese peasants to foretell seasonal changes and make adequate arrangements for agricultural production. Innovations in Cycle Space Luo Xiahong’s calendrical system includes the Sun, the Moon and the five planets. In the Book of Classics《书 经•尧典》, compiled between 800 BC and 500 BC, it is written that “if birds fly in the day and stars appear at night, it is spring; if the day is long and the stars are bright, it is summer; if the night is moderate and few stars appear at night, it is autumn; if the night is long and the stars are high in the sky, it is winter.” This ancient text forms the basis of Luo Xiahong’s calendrical system of defining the four seasons. The Taichu Li is China’s most well-preserved written calendrical system. The system calibrates the algebraic structure of cosmic images that is fundamentally different from the commonly known calendrical laws. In short, the Taichu Li is technically more advanced than the previous calendars of Yellow Emperor Calendar (黄帝历 Huangdi Li), Calendar of the Legendary Emperor Zhuanxu (颛顼 历 Zhuanxu Li), Summer Calendar (夏历 Xia Li), Shang Calendar (殷历 Yin Li), Zhou Calendar (周历 Zhou Li), and Lu Calendar (鲁历 Lu Li). Han stone relief of the solar and lunar eclipses Liu Xin and Three Sequences Calendar (Santong Li) Western Han scholar Liu Xin revised the Taichu Li by applying the Three Sequences saying of Dong Zhongshu. In computing the Three Sequences system, Liu Xin adopted the Metonic Cycle zhang as the starting point (i.e. 235 lunations in 19 years) and 1 tong (sequence) = 81 zhang = 1,539 years and 3 tong = 1 yuan (epoch) = 4,617 years, hence the “Three Sequences”. Liu Xin attempted to find the time when the Sun, the Moon and the five planets were all in conjunction with Earth. The year, the day and the hour would all be denoted by the jiazi sexagenary cycle. The computation of the coincidence was extremely complex, and it became more so as astronomical observations became more accurate. The Three Sequences Calendar, therefore, is the world’s first astronomical calendar. 9 Sci_Tec.indd FINAL.indd 9 9/10/2012 5:22:11 PM