The debates on the xuanji yuheng 璿璣玉衡 of the late Joseon dynasty had two different lines. The first was to regard it as an astronomical instrument, namely the armillary sphere (渾天儀), and to concentrate on analyzing its detailed structure. This line of the study again can be divided into two. The one was to restore the original instrument utilizing Zhu Xi's commentary. The other was to build a new kind of observational instruments based on Western astronomy that had been introduced in the late Joseon dynasty. The second line of discussion on the xuanji yuheng however denied the idea of the xuanji yuheng as an astronomical instrument. This once again can be splitted into two separate trends. The one was to adopt and to expand the traditional concept of the xuanji yuheng as the Ursa Major (北斗七星). The other proposed new interpretations. The doctrines and the annotations of Confucian canons were questioned and totally new views were presented. This last line reflected an intellectual change in the late Joseon dynasty.