Tang and Song Dynasties. There were more scientific and technological achievements in the Song dynasty (960- 1279) than in the Tang dynasty (618-907) because the two dynasties had completely different environments. The Tang period was humanistic while the Song era was much more scientific and technological. During the Song dynasty the pure sciences began to appear. Improvements in hydraulic engineering occurred, including the caisson, used either as an underwater foundation or as a floodgate. Shipbuilding technology was improved greatly when the sternpost rudder became common, and seagoing junks of substantial size were built. Chemical science, practiced in the little-known laboratories of Daoist shrines in Tang times, was applied to devastating effect on the battlefield when armies began to use gunpowder. The biological sciences thrived too and were applied for the benefit of society. Also, well-known physicians appeared in Song times, and many books on pharmaceutical botany and zoology were...