Dream Pool Essays
Pound locks were first used in China during the Song Dynasty (960–1279 AD), having been pioneered by the Song politician and naval engineer Qiao Weiyue in 984. They replaced earlier double slipways that had caused trouble and are mentioned by the Chinese polymath Shen Kuo (1031–1095) in his book "Dream Pool Essays" (published in 1088), and fully described in the Chinese historical text "Song Shi" (compiled in 1345):