Caring For The Trees, China

Science and technology
Among the technological accomplishments of ancient China were paper (not papyrus) and papermaking, woodblock printing and movable type printing, the early lodestone and needle compass, gunpowder, toilet paper, early seismological detectors, matches, pound locks, the double-action piston pump, blast furnace and cast iron, the iron plough, the multi-tube seed drill, the suspension bridge, natural gas as fuel, the differential gear for the South Pointing Chariot, the hydraulic-powered armillary sphere, the hydraulic-powered trip hammer, the mechanical chain drive, the mechanical belt drive, the raised-relief map, the propeller, the crossbow, the cannon, the rocket, the multistage rocket, etc.
Chinese astronomers were among the first to record observations of a supernova. The work of the astronomer Shen Kuo (1031–95) alone was most impressive, as he theorized that the sun and moon were spherical, corrected the position of the polestar with his improved sighting tube, discovered the concept of true north, wrote of planetary motions such as retrogradation, and compared the orbital paths of the planets to points on the shape of a rotating willow leaf. With evidence for them, he also postulated geological theories for the processes of land formation in geomorphology and climate change in paleoclimatology.
Other important astronomers included Gan De, Shi Shen, Zhang Heng, Yi Xing, Zhang Sixun, Su Song and Guo Shoujing. Chinese mathematics evolved independently of Greek mathematics and is therefore of great interest in the history of mathematics. The Chinese were also keen on documenting all of their technological achievements, such as in the Tiangong Kaiwu encyclopedia written by Song Yingxing (1587–1666).