The brilliant achievements of ancient China;
In astronomy, Luoxiahong in the Western Han Dynasty was changed into an armillary sphere, which was the main instrument for measuring the position of celestial bodies in ancient China, and it was improved in almost all dynasties. Zhang Heng of the Eastern Han Dynasty created the world's first elephant powered by water conservancy. In Yuan Dynasty, Guo Shoujing successively created and improved many astronomical instruments, such as simple instrument, high meter, inverted instrument and so on 10.
In geography, Pei Xiu was an outstanding cartographer in China during the ancient Western Jin Dynasty. Draw a map of Gong Yu area, and put forward the principles of drawing a map. Notes on Water Classics by Li Daoyuan, a geographer in the Northern Wei Dynasty, is a comprehensive geographical work with high historical, geographical and literary value, which comprehensively and systematically introduces the physical geography and economic geography of the areas where waterways flow.