Jang Yeong-sil

c. 1390 – c. 1442

Jang Yeong-sil (c. 1390 - after 1442) was a Korean inventor and engineer of the early Joseon dynasty who rose from low-born (government slave) status to high office under King Sejong. He created or improved celestial instruments, the self-striking water clock Jagyeongnu, and other devices central to Sejong's scientific program. He was dismissed from court in 1442, and the date of his death is unknown.

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Life events

Born in Dongnae (present-day Busan) to a low-born family
c. 1390

Jang was born around 1390 as a gwanno (government slave) in Dongnae; his exact birth date is not recorded.

Source: en.wikipedia.org
Birth ✓
Recruited to the royal court for his mechanical talent
c. 1421

His skill in engineering and metalwork brought him to the attention of the court, and King Sejong brought him to the palace around the early 1420s.

Source: en.wikipedia.org
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Freed from slave status and granted a government post
c. 1423

Around 1423, over objections to his low birth, Sejong released Jang from his gwanno status and appointed him to office.

Source: en.wikipedia.org
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Sent to study astronomical instruments and returned to build celestial devices
1433

After studying Chinese astronomical designs, Jang helped construct instruments such as the honcheonui armillary sphere for the royal observatory project.

Source: en.wikipedia.org
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Completed the Jagyeongnu, Korea's self-striking water clock
1434

In 1434 Jang completed the automated striking clepsydra that announced the time at the palace, one of his most famous inventions.

Source: en.wikipedia.org
Achievement ✓
Developed sundials and contributed to metal printing improvements
c. 1437

During the 1430s Jang worked on devices such as the angbu ilgu hemispherical sundial and improvements to metal movable type casting.

Source: en.wikipedia.org
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Contributed to the development of the cheugugi rain gauge
1441

The standardized rain gauge introduced by the Joseon court in 1441-1442 is associated with the scientific program in which Jang played a leading role.

Source: en.wikipedia.org
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Dismissed from court after the king's sedan chair broke
1442

In 1442 a royal palanquin whose construction Jang had supervised broke, and he was blamed, punished, and expelled from the court.

Source: en.wikipedia.org
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Died at an unknown date after his dismissal
c. 1442

Nothing is recorded of Jang's life after his expulsion from court in 1442, and the date and circumstances of his death are unknown.

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