Invented in 1441, Korea's bronze rain gauges standardized precipitation measurement 200 years before Europe. Records from these instruments provide Asia's longest continuous rainfall dataset.
Steve46814, CC BY-SA 3.0, via Wikimedia Commons
A royal decree for data
In 1441, King Sejong the Great of Korea's Joseon Dynasty mandated a scientific revolution. His kingdom's prosperity was tied to agriculture, which was in turn dependent on predictable rainfall. The existing method of gauging precipitation—measuring how deep moisture seeped into the soil—was imprecise and varied with ground conditions. To better manage water resources and create a more stable agricultural economy, King Sejong ordered the development of a standardized instrument to measure rainfall accurately.
The result was the Cheugugi (측우기), the world's first national, standardized rain gauge. The initial idea is credited to King Sejong's son, the Crown Prince Yi Hyang (later King Munjong). While the scientist Jang Yeong-sil is often associated with the invention, historical records point to the Crown Prince as the originator. The first prototype was tested in 1441, and by May 1442, a finalized design was distributed to local authorities across the entire country.
The design was simple and effective. It consisted of a bronze cylinder set upon a stone pedestal, or chugudae (측우대). The standardized dimensions were approximately 32 cm in height and 15 cm in diameter. After a rainfall, an official would dip a standardized ruler into the cylinder to measure the depth of the collected water. The time the rain started and stopped was also recorded. This data created a systematic and comparable record from every province.
A national network of science
The Cheugugi was not a standalone instrument; it was the center of a comprehensive, nationwide meteorological network. Following the final design in 1442, King Sejong ordered identical gauges sent to over 350 observation stations, from the capital to small local villages. Local magistrates were responsible for taking measurements and reporting the data to the central government. This systematic collection of rainfall information was unprecedented and occurred more than 200 years before Christopher Wren developed a similar device in Europe.
This network produced a vast and continuous set of data. Though the original 15th-century gauges were lost during Japanese invasions in the late 16th century, the system was revived in 1770 by King Yeongjo. He commissioned new gauges to be made according to the original specifications established during King Sejong's reign. These later instruments continued the data collection until 1907, providing an unbroken rainfall record for Seoul spanning approximately 130 years. These combined records are one of the world's longest continuous sets of instrumental precipitation data.
The only complete, original Cheugugi known to exist today was made in 1837 and installed at the provincial office in Gongju. It weighs 6.2 kilograms and has an inscription detailing its production date and dimensions, which faithfully match the 15th-century standard. This artifact, now a designated National Treasure of South Korea, is a remarkable early scientific system.
💡Fun Facts
The name *Cheugugi* (측우기) is a direct and functional description, translating literally to "rain-measurement instrument."
Before the Cheugugi, officials estimated rainfall by measuring the depth of moisture in the soil, a practice called *Wootaek*.
The Cheugugi system was so scientifically advanced that its measurement accuracy is comparable to modern meteorological standards.
The only complete surviving Cheugugi, made in 1837, was taken to Japan in 1915 and returned to Korea in 1971.
The National Palace Museum of Korea, located within Gyeongbok Palace, is generally open from 10:00 to 18:00, but hours can vary. It is best to check the official website.
Admission
Admission to the National Palace Museum of Korea is free. Admission to the surrounding Gyeongbok Palace requires a ticket (approx. 3,000 KRW), but is free for visitors wearing traditional Hanbok.
Accessibility
The Gyeongbok Palace grounds are large and contain unpaved roads and rough stone floors, which can be challenging for wheelchair users. However, many areas have been fitted with ramps, and accessible restrooms are available. The National Palace Museum building itself is modern and accessible.
