The Automatic Striking Clepsydra Jagyeongnoo installed in the Time Announcing Pavilion Borugak was the first clockwork with time announcing mechanisms in Korea. In June of 1432 King Sejong ordered Jang Yeong-sil make a timekeeping apparatus, whose woo...
The Automatic Striking Clepsydra Jagyeongnoo installed in the Time Announcing Pavilion Borugak was the first clockwork with time announcing mechanisms in Korea. In June of 1432 King Sejong ordered Jang Yeong-sil make a timekeeping apparatus, whose wooden figurines announce time signals automatically without human intervention. On July 1, 1434 Jagyeongnoo began to function as the Royal Court standard timekeeper. Among numerous parts only clepsydra vessels have survived up to the present and nothing of the time announcing mechanisms remains nowadays.
The authors of this paper had recently reconstructed the whole system of Jagyeongnoo, including the time announcing mechanisms as well. The mechanical and functional details of the time-telling apparatus were described in this paper. The characteristic aspects of Jang's ingenious devices, such as float-rod and ball-rack mechanism, ball-relay mechanism, and twelve double-hour announcing mechanism, were evaluated at the viewpoint of history of technology.