(Picture from ChinaCulture.org.)
MedievalPOC is doing a POC Scientists and Mathematicians week this week! This is a topic I wanted to learn more about anyway, so I thought maybe I could contribute. I noticed that there hasn’t yet been an article about my favorite medieval Chinese astronomer/geologist/mathematician/inventor/poet/diplomat/all-around awesome dude 沈括 (Shen Kuo) (1031 - 1095 AD) Somebody else could probably write a better article than I can, since I’m just a beginner to this topic, but here goes anyway…!
Shen Kuo lived during the Northern Song Dynasty (960-1127), which was a very fertile intellectual period for medieval China. Inventions during the Song Dynasty included gunpowder weapons, the canal pound lock, windmills, movable-type printing, and the compass, as well as great advances in metallurgy and shipbuilding.
During his lifetime, Shen Kuo had his fingers in every imaginable field of learning, making extensive studies of nature and of human inventions while traveling around China as a civil servant, diplomat, and military commander. He’s what Europe would call (four centuries later) a “renaissance man”. ;-) Most of what we know about Shen Kuo comes from an enormous book called the Dream Pool Essays (梦溪笔谈 Mengxi Bitan) that he wrote during his retirement. The whole book is on Project Gutenberg, if you happen to be able to read medieval Chinese. Here’s a few of the highlights:
The compass: Most of us know that the magnetic compass is a Chinese invention, but before the Song dynasty it was mainly used for ritual and fortune-telling purposes. Shen Kuo was the first person to measure the difference between Magnetic North and True North, and by so doing helped make the compass into a reliable navigation aid for Song Dynasty ships.
Geology: During his extensive travels around China, Shen Kuo observed fossilized seashells far inland in Shanxi province, as well as petrified bamboo in Yan’an province, which was too dry for bamboo to grow. He deduced that Shanxi must once have been on the sea, and that northern China must once have been much wetter, and proposed a theory of climate and geological change via erosion, mountain uplift, and soil deposition. He also published quite accurate maps, using a consistent scale, based on his geographical surveys.
Astronomy: Shen Kuo made careful observations of the motions of the planets and the phases of the moon, similar to what Tycho Brahe would do centuries later. To make more accurate measurements, he improved the design of the astronomical instruments used at the time — armilarry sphere, gnomon, sighting tube, and water clock. He accurately described the retrograde motion of the planets, proposed the theory that the moon was a sphere lit by the sun, and explained the mechanism of eclipses. Thanks the accuracy of his measurements, he discovered that the position of the Pole Star and the orbits of the planets had shifted slightly since their measurement 350 years earlier by Yi Xing. (Apparently his political enemies used this to get him into a lot of trouble at court, since Yi Xing was highly respected and criticizing his work was considered unacceptable!)
Archaeology: Speaking of criticizing ancient texts, Shen Kuo carefully dug up ritual artifacts of earlier dynasties and argued that physical evidence of the past should be given more weight than textual records.
Math: He solved a lot of complex problems of trigonometry and circular geometry, inspired by his time in the government and military: the calculation of areas for land tax, the efficient packing of spheres, and the terrain space needed for military formations. He also used combinatorics to calculate the number of possible positions in a Go game, and wrote about the mathematical relationships in music.
Medicine: Shen Kuo showed that the human throat has two openings (the trachea and the esophagus), debunking what was at the time the mainstream theory that there were three openings (for solid, liquid, and air).
Besides science, he also wrote extensive poetry, political treatises, and art criticism, and wrote the earliest known description of movable-type printing, which he tells us was invented by a man named Bi Sheng.
So overall, Shen Kuo had a pretty amazing life, and contributed to many different fields. Today his tomb is a tourist attraction in the city of Hangzhou.
(Most of this information is from Wikipedia.)