Jianpingyi shuo 簡平儀說

Jianpingyi shuo 簡平儀說 "On the simple levelling tool" is a book on astronomy written during the late Ming period 明 (1368-1644) by the Jesuit missionary Jesuit Sabatino de Ursis (1575-1620; Ch. Xiong Sanba 熊三拔).

The "simplified levelling tool" (jianpingyi 簡平儀) was designed by de Ursis based on the principles of the astrolabe. It consisted of two plates: the celestial plate (tianpan 天盤) was positioned below as a square base, while the terrestrial plate (dipan 地盤) was above and had a hollowed-out semicircle, making alignment easier. A pivot was set between the two plates, allowing them to rotate.

This book primarily explains using the tool to observe the Sun's longitude and latitude, determine time, and measure latitude. It also briefly discusses the concept of the Earth as a sphere.

It was printed in the Ming period and is included in the series Tianxue chuban 天學初函, Shoushange congshu 守山閣叢書, Siku quanshu 四庫全書 and Zhong-Xi suanxue congshu 中西算學叢書.