<Cheukwoogi> was invented by Crown Prince Yi Hyang (later Munjong) in 1441 during the reign of King Sejong and completed by Jang Yeong-sil. Although it is a simple tin can as a device for measuring rain, it is the pinnacle of empirical science that measures the amount of rain most accurately, preventing disasters such as water floods and being very useful when farming. In the West, Gastelli of Italy made the first rain gauge in Rome in 1639.