Joseon · Historical figure
Jang Yeongsil
A Joseon engineer involved in water clocks and astronomical instruments.
Key events
As a court engineer under Sejong, he made astronomical instruments and the Jagyeongnu and Ongnu water clocks, introducing automatic signaling into royal timekeeping.
Legacy
He helped develop timekeeping and observational instruments such as Jagyeongnu. Royal support and collaboration mattered alongside individual ingenuity.