shen kuo

 

Born 1031 in Hangzhou, Zhejiang province, China – Died 1095 in Ching-k’ou, China

 

 

Shen Kuo also known as Shen Gua or Shen Kuo  was a Han Chinese polymathic scientist and statesman of the Song dynasty (960–1279). Excelling in many fields of study and statecraft, he was a mathematician, astronomer, meteorologist, geologist, zoologist, botanist, pharmacologist, agronomist, archaeologist, ethnographer, cartographer, encyclopedist, general, diplomat, hydraulic engineer, inventor, academy chancellor, finance minister, governmental state inspector, poet, musician and ultimate abstract thinker. A civil servant, his roles include serving as the head official for the Bureau of Astronomy in the Song court, as well as an Assistant Minister of Imperial Hospitality.

 

Magnetic North

In his Dream Pool Essays or Dream Torrent Essays of 1088, Shen was the first to describe the magnetic needle compass, which would be used for navigation (first described in Europe by Alexander Neckam in 1187). Shen discovered the concept of true north in terms of magnetic declination towards the north pole, with experimentation of suspended magnetic needles. This was the decisive step in human history to make compasses more useful for navigation and may have been a concept unknown in Europe for another four hundred years.

 

 

s29800570.jpg

 

 

Understanding the History of Earth

Alongside his colleague Wei Pu, Shen planned to map the orbital paths of the Moon and the planets in an intensive five-year project involving daily observations, yet this was thwarted by political opponents at court. To aid his work in astronomy, Shen Kuo made improved designs of the armillary sphere, gnomon, sighting tube, and invented a new type of inflow water clock. Shen Kuo devised a geological hypothesis for land formation (geomorphology), based upon findings of inland marine fossils, knowledge of soil erosion, and the deposition of silt. He also proposed a hypothesis of gradual climate change, after observing ancient petrified bamboos that were preserved underground in a dry northern habitat that would not support bamboo growth in his time. Shen Kuo claimed that fossilised plants were evidence for changes in climate. He recognised fossils of certain sea creatures in rock far from the sea and understood what this meant. Observing seashells in strata of the T’ai-hang Shan mountains, he deduced that these mountains, though now far from the sea, must once have been a seashore.

 

Mapping 

He was the first literary figure in China to mention the use of the drydock to repair boats suspended out of water, and also wrote of the effectiveness of the relatively new invention of the canal pound lock. Although Ibn al-Haytham (965–1039) was the first to describe camera obscura, Shen was the first in China to do so, several decades later. Shen wrote extensively about movable type printing invented by Bi Sheng (990–1051), and because of his written works, the legacy of Bi Sheng and the modern understanding of the earliest movable type has been handed down to later generations.

Following an old tradition in China, Shen created a raised-relief map while inspecting borderlands. The three-dimensional maps of areas he visited made from wooden plates on which sawdust mixed with glue and melted wax were used. His description of an ancient crossbow mechanism which he himself unearthed proved to be a Jacob’s staff, a surveying tool which wasn’t known in Europe until described by Levi ben Gerson in 1321. While subprefect of Ning-Kuo in Anhwei province in 1061, Shen undertook a cartographic survey and then undertook another major land reclamation programme. Again it was very successful and after Shen passed national examinations in 1063 and moved to Yang-chou, the governor realised that here was someone of outstanding ability and recommended him for an appointment at court in the capital Kaifeng in Honan province.

 

Government & Peace Maker

Shen now undertook a series of reforms initiated by the Northern Song Dynasty reformer Wang Anshi.  Wang’s opponents in government saw Shen as someone traveling around the country obtaining support for Wang’s reform programme and they began to conspire against him. However, Shen was so successful in the tasks he was given that he continued to be asked to undertake projects of major national importance. In 1075 he undertook the task of revising the defence strategy of the country, and he undertook very successful negotiations with the Khitan tribes in the north who were threatening to invade. Using his knowledge of history to refute the claims of the Khitan tribes to Chinese territory, he brought peace to the area which lasted for a number of years. Returning to the capital Kaifeng, Shen was appointed to the Imperial Academy and appointed Finance Commissioner in 1077. His writings on the theory of supply and demand, made while holding this office, are quite remarkable. He wrote on methods of forecasting prices, the currency supply, price controls, market intervention and other topics which were not studied again in this depth until modern times.

 

 

Wang_Shimin-After_Wang_Wei's_Snow_Over_Rivers_and_Mountains.jpg

An art critic Shen admired the work of Wang Wei

Snow over rivers and mountains”

 

False Accusations 

Having reached a position of great power in the government, pushing through effective reforms with great success, he was accused of dishonest practice in the autumn of 1077. These charges were completely false but brought by political opponents of Wang’s reform programme. Shen was a brilliant man, but his skill was in accomplishing tasks and not in political manoeuvring. He had suddenly become exposed since the politically skilful Wang had become frustrated and had retired in the autumn of 1076. It was Wang’s replacement who brought the false charges against Shen.

Shen was sent to Shenxi province as Commissioner for Prefectural and Military Affairs. There, in 1081, he organized an advance against the Tanguts winning major victories and extending the control of the Song dynasty over new regions. The emperor was delighted and Shen made proposals to him to fortify the region. However, there were still those who were working against him and his plans were overturned. Instead, plans for fortifications which he considered useless were acted on instead. An attack by the Tanguts saw the Sung troops defeated and sustain heavy losses. Although he had been in no way responsible for the defeat he was blamed by Wang’s successor and was relieved of his command and banished.

 

Mapping Return

This seems to have been fortunate as far as science is concerned since after he was banished he wrote his scientific works. He was banned from taking part in official events and made to live essentially under house arrest. He was free to undertake scientific work, however, and he worked on a project he had begun at the Emperor’s request in 1076, namely to produce maps of all Chinese territory. He produced 23 maps, all drawn to the scale of 1:900,000. Shen knew that maps tended not to survive for long, whereas books had a better chance of long-term survival. Therefore, he encoded his maps in terms of directional coordinates and distances, writing;

“Thus although in later generations the maps may be lost, given my book the territorial divisions may be laid out according to the twenty-four directions, and the maps speedily reconstructed without the least discrepancy.”

Maps are of great military significance, as well as scientific interest, so his project found favour with the government. After six years of being subjected to what was close to house arrest, Shen was allowed to live in a place of his own choosing. He already had purchased a property when he had been a leading figure ten years earlier but he had never seen his property on the outskirts of Jiangsu (Zhenjiang). In 1086 he was allowed to visit it and found a place of great beauty which he had dreamt of for many years. He named it Dream Brook and in 1086 he received a pardon, a state pension, and permission to live where he chose. He spent the last seven years of his life in isolation at Dream Brook. It is a remarkable scientific document which contains his work on mathematics, music, astronomy, calendars, cartography, geology, optics and medicine. There is also a reference to a magnetic compass and its use in cartography.

 

Mathematics 

In terms of other achievements, Shen took a much more abstract view of mathematics than the Chinese generally did. Most Chinese mathematics was motivated by practical problems, but Shen was happy to look at mathematical problems for their own sake. In his astronomical work, Shen had to convert from coordinates given in equatorial form to those given in ecliptic form. This requires at least some understanding of spherical geometry and trigonometry. In fact, Shen demonstrated a remarkable ability to view spatial arrangements and he gave an approximate formula for the length of a circular arc in terms of the cord subtending the arc. There is evidence in this work that he was coming close to trigonometry, effectively having the sine function for his use. Shen’s work in astronomy is remarkable in many ways. He attempted to explain why the motion of the planets across the sky was as observed with periods of retrograde motion. Other Chinese astronomers had only looked at the positions of the planets without ever trying to explain what was observed. Unlike Greek astronomers who tried to explain all motions as circular, Shen proposed that planets moved in a willow leaf motion composed with circular motion around the earth. He is also said to have constructed an armillary sphere, a water clock, and a bronze gnomon, a pointer whose shadow gives the time of mid-day.

 

Legacy 

The breadth of interest alone does not account for Shen’s importance for the study of the Chinese scientific intellect. Another aspect is his profound technical curiosity. Above all, one is aware in Shen, as in other great scientific figures, of a special directness. A member of a society in which the weight of the past always lay heavily on work of the mind, he nevertheless often cut past deeply ingrained structures and assumptions.

Nathan Sivin proposes that Shen was the first in history to “make a clear distinction between our unconnected experiences and the unitary causal world we postulate to explain them,” which Biderman and Scharfstein state is arguably inherent in the works of Heraclitus, Plato, and Democritus as well. The articles are also accredited to the work of J J O’Connor and E F Robertson / further reading.