Pyongyang, August 22 (KCNA) -- Jang Yong Sil was a celebrated technician who contributed to the development of astronomy and meteorology.

Jang, born into a slave family, invented new astronomical observation apparatuses, metal types and musical instruments.

His talents were so great that he was known to Sejong King of the Ri Dynasty (1392-1910).

He joined in casting metal types for several years from 1432 and invented various astronomical observation apparatuses.

After studying machines made in other countries, he invented Jagyokru, an automatic water clock.

He then made a solar clock and other observation instruments needed for a large observatory.

He also invented a copper rain gauge, which was used throughout the country for hundreds of years.