Jang Yeong-Sil: Inventor of the striking clepsydra during the reign of King Sejong in Joseon

Abstract

Jang Yeong-sil was the Chief Royal Engineer in charge of the engineering and construction project for re-equipping the Royal Observatory during the reign of King Sejong (r. 1432-1438). Jang devoted himself to making five kinds of astronomical instruments and ten timekeepers. In this paper the life and contributions of Jang are introduced along with his major invention: the striking clepsydra. This paper also discusses how the clepsydras were handed down and utilized by Jang’s successors in the making of astronomical clocks in Joseon. Not only did Jang assimilate the techniques of his Korean, Chinese and Islamic predecessors, but he also was a creative and innovative engineer. Jang is in some ways the most articulate among those in a long tradition of “automation” in Asian science and technology, where automation is a matter of submission to the laws of nature rather than the means of controlling nature, as seen in our time. This paper positions Jang’s work as a catalyst for new directions in automation and robotic arts. He was one of those mechanical geniuses who contributed to the advancement of pre-modern science and technology