《晋书·志·第一章》
到汉太初年间，落下闳、鲜于妄人、耿寿昌等人制造圆仪来历法度数。
暨汉太初，落下闳、鲜于妄人、耿寿昌等造员仪以考历度。
In the early years of Emperor Wu of the Han Dynasty, Xiaohong, Xianyuwangren, and Gengshouchang created a circular instrument to deduce the legal degree.