A brass armillary developed by Kuo Shou-ching in the Yuan dynasty (1271-1368) simplified the earlier models and improved accuracy; it can be seen today at the Tse-chin Mountain observatory in Nanking.
元朝郭守敬的銅製渾天儀更精美與實用，他簡化歷代渾天儀的結構（因稱簡儀），不僅使用方便、提高精確度，且開創現代望遠鏡的架筒法，現仍存於南京紫金山天文台。