In improving agricultural technology, Sejong contributed to the sciences of astronomy and meteorology (weather). He invented a calendar for the Korean people and ordered the development of accurate clocks. Droughts plagued the kingdom and King Sejong directed every village to measure the amount of rainfall.
His son, the crown prince, later called King Munjong, invented a rain gauge while measuring rainfall at the palace. Munjong decided that instead of digging into the earth to check rain levels, it would be better to use a standardized container. King Sejong sent a rain gauge to every village, and they were used as an official tool to measure the farmer's potential harvest. Sejong also used these measurements to determine what the farmer's land taxes should be. The rain gauge was invented in the fourth month of 1441. The invention of the rain gauge in Korea came two hundred years before inventor Christopher Wren created a rain gauge (tipping bucket rain gauge circa 1662) in Europe.
On March 15, 1950, New York City hired Dr Wallace E Howell as the city's official "rainmaker".