Gov’t designates 18th-century astronomical clock as national treasure

Yoo Geum (1741-1788) is a forgotten Silhak (Realist School of Confucianism) scholar in the 18th century. Also the uncle of Yoo Deuk-gong, Yoo Geum was not entitled to seek a government post since he was the son of a concubine. But he was an outstanding scientist and an inventor, making a variety of machines, such as a pump, since he was a child. An invention he developed in 1787 left a footprint in the history of science in East Asia. The invention was called, “Hongaetongheonui,” which was a new interpretation of Western astronomical clock “Astrolabe.”

The Cultural Heritage Administration on Wednesday said it designated “Hongaetongheonui” as Treasure No. 2032 since it shows a high level of astronomic knowledge of the Joseon Dynasty. Yoo Geum’s “Hongaetongheonui” is known to be the only astronomical clock that has existed in East Asia.

The “Hongaetongheonui” was first known to East Asia when Lee Ji-jo (1565-1630) of the Ming Dynasty published the translation of the manual of the Islamic astronomical clock Astrolabe in the early 17th century. The “Hongaetongheonui” consists of two parts: the disc plate that measures the location of stars and time and the T-shaped plate that points at the location of stars. The T-shaped plate is placed on top of the disc plate using a pin so that it can rotate freely.

But its whereabouts had been unknown after it was sold to Japan around 1930 during the Japanese colonial period. It appeared in the public eye in 2002 when its existence was known to Japanese scholars. Thanks to the effort of Jeon Sang-woon (1928-2018), former president of Sungshin Women’s University and history of science scholar, the “Hongaetongheonui” returned to the country in 2007. Currently, the “Hongaetongheonui” is kept at the Museum of Silhak in Namyangju, Gyeonggi Province.


Won-Mo Yu onemore@donga.com