Editing Water clock (section)

===Korea===

{{Main|Jang Yeong-sil#Water Clock}}

[[File:BoRuGak_Jagyeongnu.JPG|thumb|right|Jang Yeong-sil's self-striking water clock, the [[Borugak Jagyeongnu]]]]
In 718, [[Unified Silla]] established the system of clepsydra for the first time in Korean history, imitating the Tang Dynasty.<ref>{{cite book|first=Z.|last=Xu|year=2021|chapter=The Spread of Traditional Chinese Mathematics in the Sinosphere and Its Influence|title=The High Tide of Science and Technology Development in China: History of Science and Technology in China|volume=3|pages=413–426|doi=10.1007/978-981-15-7847-2_11|isbn=978-981-15-7846-5 |chapter-url=https://link.springer.com/content/pdf/10.1007/978-981-15-7847-2_11.pdf}}</ref> In 1434, during [[Joseon]] rule, [[Jang Yeong-sil]] ({{ko-hhrm|hangul=장영실|hanja=蔣英實}}), a palace guard and later chief court engineer, constructed the [[Borugak Jagyeongnu]] or self-striking water clock of Borugak Pavillion for [[Sejong the Great]].

What made his water clock self-striking (or automatic) was using jack-work mechanisms: three wooden figures or "jacks" struck objects to signal the time. This innovation no longer required the reliance of human workers, known as "rooster men", to constantly replenish it.{{Citation needed|date=December 2020}}

The uniqueness of the clock was its capability to announce dual-times automatically with visual and audible signals.<ref>{{cite book|last1=Koetsier|first1=Teun|last2=ceccarelli|first2=marco|title=Explorations in the History of Machines and Mechanisms: Proceedings of HMM2012|date=5 April 2012|publisher=Springer Science & Business Media|isbn=9789400741324|page=90|url=https://books.google.com/books?id=-x9NHOLSnNUC&pg=PA90|access-date=27 March 2017|language=en}}</ref> Jang developed a signal conversion technique that made it possible to measure analog time and announce digital time simultaneously as well as to separate the water mechanisms from the ball-operated striking mechanisms.<ref>{{cite book|last1=Koetsier|first1=Teun|last2=ceccarelli|first2=marco|title=Explorations in the History of Machines and Mechanisms: Proceedings of HMM2012|date=5 April 2012|publisher=Springer Science & Business Media|isbn=9789400741324|page=95|url=https://books.google.com/books?id=-x9NHOLSnNUC&pg=PA95|access-date=27 March 2017|language=en}}</ref> The conversion device was called ''pangmok'', and was placed above the inflow vessel that measured the time, the first device of its kind in the world.<ref>{{cite book|title=Fifty Wonders of Korea - Vol. 2|publisher=KSCPP|url=http://www.kscpp.net/LinkClick.aspx?fileticket=lILBCCXDCSk%3d&tabid=144&mid=528|archive-url=https://web.archive.org/web/20170327171319/http://www.kscpp.net/LinkClick.aspx?fileticket=lILBCCXDCSk%3d&tabid=144&mid=528|access-date=27 March 2017|archive-date=2017-03-27}}</ref> Thus, the Borugak water clock is the first hydro-mechanically engineered dual-time clock in the history of horology.<ref>{{cite book|last1=Ceccarelli|first1=Marco|title=Distinguished Figures in Mechanism and Machine Science: Their Contributions and Legacies|date=21 May 2014|publisher=Springer|isbn=9789401789479|page=111|url=https://books.google.com/books?id=yavIAwAAQBAJ&pg=PA111|access-date=27 March 2017|language=en}}</ref><ref>{{cite book|last1=Pisano|first1=Raffaele|title=A Bridge between Conceptual Frameworks: Sciences, Society and Technology Studies|date=30 June 2015|publisher=Springer|isbn=9789401796453|page=364|url=https://books.google.com/books?id=eUUPCgAAQBAJ&pg=PA364|access-date=27 March 2017|language=en}}</ref>