Water-powered mills

Timeline

1. c. 1070–1085Bianjing, Northern Song · KaifengThe court set up official water mills along the Bian River, using water power to grind wheat and tea, processing grain for the capital's million-strong population and imperial guards while increasing fiscal revenue; the genre painting 'Water Mill' depicts such large water-powered workshops.
2. 1086Bianjing, Northern Song · KaifengSu Zhe submitted the 'Memorial Requesting Abolition of Official Water Mills,' arguing that official mills blocked water and hindered grain transport, competed with the people for profit, and that dredging costs exceeded annual mill profits, requesting their abolition; court policy fluctuated several times around the Yuanyou reforms.
3. c. 1081–1090Huai region, Northern Song (Changge etc.) · Xuchang'Water-driven linked mills,' in which one vertical wheel drove multiple millstones, were used in the Huai River basin for grinding flour and making tea cakes; forms recorded later by Wang Zhen's 'Agricultural Treatise,' such as one wheel linked to two or nine mills, were already well developed in Northern Song practice.