Cheugugi

(This is mere a translated document of 측우기 on wikipedia.-Editor's comment)

Cheugugi(Hangul:측우기, Hanja:測雨器)is the world first rain gauge which is invented and utilized by Joseon Dynasty of Korea. It was invented and supplied to each Provincial offices during the King Sejong the Great's reign. Now(May 2010), there are just one Joseon dynasty's Cheugugi left, Geumyeong Cheugugi(Hangul:금영측우기, Hanja:錦營測雨器), literally means Cheugugi installed on provincial office's yard. Which is designated as a National Treasure #561 of Korea, and was installed in provincial office of Gongju city, 1837 by the King Yeongjo(the 21st King of the Joseon). In addition, also the official record of the rainfall by Cheugugi form the King Jeongjo's reign to Emperor Gojong's reign is preserved.

The intention of the Cheugugi and operation

Intention

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. However the method to measure rainfall in those days was primitive, measuring the depth of rain water in puddles. 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, the King Sejong the Great ordered the Gwansanggam(Hangul:관상감,Hanja:觀象監)(which was the Joseon kingdom's research institute of astronomy, geography, calendar and weather) to build a rain water container, the Cheugugi, made of iron in August 1441 (according to the lunar calendar). In the early days of the Cheugugi, it was mainly used in the capital area only. In 1442(which was the twenty fourth year of the reign of King Sejong the Great), the King ordered the Gwansanggam again to design a standardized system to measure and record the rainfall. He also ordered his Provincial governors, appointed by the King, to install the same Cheugugi in the courtyard of each provincial office, where the governors themselves would measure and record the rainfall. It was originally made of iron, but there were copper and ceramic ones built in later times.

Exterior Features

As it is described above, the Cheugugi was mainly made of iron. 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 resonable height of the Cheugudae makes the splashed water can't flow into the Cheugugi. The depth of the preserved Cheugugi is about 32 cm and the diameter is about 15 cm.

Operation

It is estimated, the measuring rainfalls by the standardized Cheugugi is institutionalized from May 8, 1442, by lunar calendar. From that day, the word "Chegugi" has came on the official records of the Annals of the Joseon Dynasty(조선왕조실록). And measuring the rainfall is operated, after the rain stopped, by dipping a ruler and recorded by Poon(Hangul:푼, Hanja:分)Units(approximately 0.303 cm(0.120 inch)). Furthermore, the information of the time when the rain began and stopped is also recorded by each cases, always, throughout the nation.

Etc.

Some Cheugudaes(the support) are existing even nowadays, as follows

• The Gwansanggam Cheugudae
• Daegu Sunhwadang Cheugudae(established on Daegu Provincial office by Joseon dynasty)
• Changdeokgung Palace's Cheugudae(Moved to the National Palace Museum of Korea)
• Tongyeong Cheugudae
• Yeon-gyeong-dang(the royal residence located in forbidden garden of Changdeokgung Palace) Cheugudae

There is also Ma-jeon-gyo(Bridge) which is generally known as Supyo-gyo across the Cheonggyecheon(stream flows center of Joseon Era's Seoul City(Inside area of the Seoul wall), near the Gyungbok Palace). The generally known name was originated from the Supyo-seok attached on the pier of the bridge, and the Supyo-seok's meaning and function is "the water level gauge" of Cheonggyecheon, telling how much the stream's water level is risen by a rain. It also established in King Sejong the Great's reign(accurately 2nd year of his reign) and is existing nowadays. But 1958 when the Cheonggyecheon was covered as a road by the Korean Government, it was moved to Jang-chung park and it is located there till now. There was a plan to move the bridge to its original location, during the Cheonggyecheon restoration. But, unfortunately the plan can't be fulfilled, cause there was a difference between the restored width of the Cheonggyecheon and the Bridge's length. So, the bridge located in Jang-chung Park, as it was, till these days.