Song Dynasty - Technology, Science, and Engineering - Polymaths, Inventions, and Astronomy

Polymaths, Inventions, and Astronomy

Polymath figures such as the statesmen Shen Kuo and Su Song (1020–1101) embodied advancements in all fields of study, including biology, botany, zoology, geology, mineralogy, mechanics, horology, astronomy, pharmaceutical medicine, archeology, mathematics, cartography, optics, art criticism, and more.

Shen Kuo was the first to discern magnetic declination of true north while experimenting with a compass. Shen theorized that geographical climates gradually shifted over time. He created a theory of land formation involving concepts accepted in modern geomorphology. He performed optical experiments with camera obscura just decades after Ibn al-Haytham was the first to do so. He also improved the designs of astronomical instruments such as the widened astronomical sighting tube, which allowed Shen Kuo to fix the position of the pole star (which had shifted over centuries of time). Shen Kuo was also known for hydraulic clockworks, as he invented a new overflow-tank clepsydra which had more efficient higher-order interpolation instead of linear interpolation in calibrating the measure of time.

Su Song was best known for his horology treatise written in 1092, which described and illustrated in great detail his hydraulic-powered, 12 metres (39 ft) tall astronomical clock tower built in Kaifeng. The clock tower featured large astronomical instruments of the armillary sphere and celestial globe, both driven by an early intermittently working escapement mechanism (roughly two centuries before the discrete verge escapement of true mechanical clocks appeared in medieval clockworks). In addition, Su Song's clock tower featured the world's first endless power-transmitting chain drive, an essential mechanical device found in many practical uses throughout the ages, such as the bicycle. Su's tower featured a rotating gear wheel with 133 clock jack manikins who were timed to rotate past shuttered windows while ringing gongs and bells, banging drums, and presenting announcement plaques. In his printed book, Su published a celestial atlas of five star charts. These star charts feature a cylindrical projection similar to Mercator projection, the latter being a cartographic innovation of Gerardus Mercator in 1569.