Cheugugi

Cheugugi (Hangul: 측우기, Hanja: 測雨器) is the first well-known rain gauge invented and used during the Joseon dynasty of Korea.

In the early days of the Joseon dynasty, there was a system to measure and report a region's rainfall for the sake of agriculture.

This method could not tell the exact rainfall, because there are differences in the amount of rainwater absorbed into the ground by the nature of the local soil.

To prevent errors of this kind, King Sejong the Great ordered the Gwansanggam (Hangul: 관상감, Hanja: 觀象監) (the Joseon kingdom's research institute of astronomy, geography, calendar and weather) to build a rainwater container, the Cheugugi, made of iron in August 1441 (according to the lunar calendar) based on the idea of his Crown Prince, who later became Munjong of Joseon.

By observing the preserved one, it is generally characterized by its oil-drum shape which is fixed on the hexahedral stone support, Cheugudae (측우대).

The rainfall is measured by dipping a ruler and recorded by poon (Hangul: 푼, Hanja: 分) units (approximately 0.303 cm (0.120 inch)).