But in fact, as early as the reign of the Western Han's Xuan Di, the minister in charge of agriculture, Geng Shouchang, is recorded as having "an astronomical device cast of bronze, with which to map the heavens."
但早在紀元前七十四年西漢宣帝時的「農業部長」耿壽昌，已「鑄銅為渾象儀，以測天文」。