Rain Gauge (Cheugugi)

Timeline

1. 1441Courtyard of the royal palace in Hanyang · HanyangBecause differing soil absorption rates made 'observing ground moisture' unable to compare rainfall across districts, Crown Prince Yi Hyo proposed collecting rain in a bronze vessel and measuring the water depth with a ruler. The Gwansanggam and artisans including Jang Yeong-sil fashioned a court instrument accordingly, converting precipitation from experiential observation into recordable depth data.
2. 1442Provincial governorates of the eight provinces of Joseon · Joseon dynastySejong ordered the Ministry of Revenue and the Gwansanggam to standardize the instrument: a mouth diameter of seven chon and a depth of one chi five chon, cast in iron or bronze, with rainfall depth and start/end times recorded in units of pun and chon. Each provincial governor was required to install an identical rain gauge in the courtyard of his office and report regularly, creating a nationally comparable archive of precipitation.
3. 1443–1500Hanyang and provincial government offices · Joseon dynastyRainfall data informed the Ministry of Revenue's assessments of the harvest, deliberations on tax remissions and relief, and adjustments to land taxes, and was used alongside the water gauge (a river-level measuring rod). This practice embedded meteorological observation within the centralized bureaucratic system of agricultural administration, making rainfall a national statistic comparable across years.
4. 1770Geumyeong in Gongju and elsewhere · Joseon dynastyAfter the wars of the late 16th century the rain gauge system was suspended for a time; in the 18th century the court recast gauges according to Sejong's original standard and restored observations in the provinces. Artifacts such as the 1837 Geumyeong rain gauge were designated cultural properties, transforming the rain gauge from a practical agricultural instrument into a standardized heritage object in the history of science and meteorology.