Chinese inventor who is best known for his invention (in 976) of the chain drive for mechanical clocks. The first chain drive, designed by Philon of Byzantium in about 250 b.c., was used in a catapult. Mechanical clocks did not appear in Europe until the early fourteenth century, and the first Western chain drive was not developed until 1770.
"Chang Ssu-Hsün." Science and Its Times: Understanding the Social Significance of Scientific Discovery. . Encyclopedia.com. (September 25, 2018). http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/chang-ssu-hsun
"Chang Ssu-Hsün." Science and Its Times: Understanding the Social Significance of Scientific Discovery. . Retrieved September 25, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/chang-ssu-hsun