A clepsydra is a device designed to measure time by observing a flow of water, and was used as a standard timepiece for the state starting in the Three Kingdoms period. One of the first unique mechanisms developed in Korea appeared in 1434 (the 16th year of the reign of King Sejong of the Joseon Dynasty) when Jang Yeong-sil made a device comprised of bells, gongs and drums to automatically tell the time. The clock did not last long, however. Another novel water clock in 1536 (the 31st year of the reign of King Jungjong), some of whose parts have survived to the present day. While the Korean clepsydra appeared later than the Ming device currently preserved in Guangdong Province, China, its size and elaborate crafting have led to its being regarded as a more valuable cultural artifact.