Chapter 43 Section 9 Shen Kuo and "Mengxi Bi Tan"

Shen Kuo (AD 1031-1095), whose characters are preserved, was born in Qiantang (now Hangzhou, Zhejiang).He was an outstanding scientist in the Northern Song Dynasty, and he had profound attainments in many fields of science.History books say that he is "erudite and good at writing, and has written on astronomy, local chronicles, legal calendar, music, medicine, and divination." The most remarkable figure in the whole history of science". "Mengxi Bi Tan" was written by Shen Kuo when he lived in Mengxi Garden in Runzhou (now Zhenjiang, Jiangsu Province) in his later years.The book records his life's experience and research experience, and the content covers a wide range.Among them, items related to science and technology accounted for more than 1/3, involving mathematics, astronomy, calendar, physics, chemistry, geography, meteorology, geology, metallurgy, weapons, water conservancy, architecture, animals and plants, and medicine. "Mengxi Bi Tan" is now regarded as an encyclopedia-style work and a precious document in the history of science and technology.

Shen Kuo made many contributions to science, the more prominent ones are: Mathematics He pioneered the research directions of "Gap Accumulation" and "Circle Convergence" in ancient Chinese mathematics.The gap product technique belongs to the summation problem of high-order arithmetic series, and he created the correct solution formula.The art of circling is a problem of finding the arc length when the circle diameter and sagittal height of the bow are known, and an approximate formula for the solution is also given. Astronomical Calendar He attaches great importance to astronomical observations. In order to test the distance between Polaris and the North Pole, he personally designed a peep tube that can keep Polaris within the field of view. He observed continuously for three months, measured three times a night, and drew more than 200 pictures. , thus drawing the conclusion that the Polaris at that time was more than three degrees away from the North Pole.For the first time, he proposed the conclusion that the length of a day during the winter solstice and the summer solstice are not equal, and proposed that the winter solstice is longer and the summer solstice is shorter.He insisted on the scientific understanding that "the moon has no light" and "the sun shines because the light is the ear", and after half-coated with powder, the side view is like a hook, and the front view is a circle, vividly demonstrating the phenomenon of the moon's waxing and waning.He also put forward suggestions and design schemes for improving the armillary sphere, floating leak, and shadow watch.The twelve solar calendar he proposed can make up for the defect of uneven distribution of solar terms in each month.The Shawneberg calendar, which was used by the United Kingdom in the 1930s to count agricultural climate, is similar to the twelve solar calendars, but it is more than 800 years later than Shen Kuo.

Physics Shen Kuo has studied the imaging of concave mirrors, has discovered the focal point, and proposed that the object does not form an image at the focal point, which is a big step forward from the research of Mohism.In order to demonstrate the resonance phenomenon of sound, he conducted a resonance experiment.He cut a paper figurine, put it on the fundamental string of the qin, and plucked the corresponding overtone string, the paper figurine would jump, but plucked the other strings, the paper figurine would not move.Pluck the response string of another zither, and the paper figurine also jumps.The same experiment in Europe did not appear until the 17th century.

He discovered snail fossils in the Taihang Mountains, and deduced that this place used to be a seashore. He further pointed out that the North China Plain was an alluvial plain, which was formed by the sediment deposition from the upper reaches of the Yellow River, Zhang River, and Hu (huhu) Tuo River.This is the world's earliest scientific insight into the causes of flood plains.He once drew 20 maps of states and counties in the world, including a large national map, a small map, and 18 sub-maps, and created a three-dimensional terrain model. ………… In addition to his own research results, "Mengxi Bi Tan" also recorded many latest technological inventions at that time.For example, the four installation methods of the early compass mentioned above, and Bi Sheng's clay movable type printing are all known to later generations with the help of Shen Kuo's description.