측우기 is a traditional Korean rain gauge invented by Jang Yeong-sil during the Joseon Dynasty. It was designed to measure the amount of rainfall accurately, helping farmers and officials monitor weather conditions. The device consists of a cylindrical container with a scale marked on the side. As rainwater collects in the container, the level indicates the amount of precipitation. This simple yet effective tool played a crucial role in agricultural planning and water management in historical Korea.