為古代中國用來觀測星象的儀器，主要由三層環圈所組合而成，由外而內分別為六合儀、三辰儀、四游儀，這些圓形的骨架代表天體經緯度和赤道、黃道、子午圈等。也隱含著各種科學知識間密不可分的關係。

The instrument used in ancient China for observing celestial phenomena consists of three concentric rings. From outermost to innermost, they are the Hexagram Instrument, Three Stars Instrument, and Four Travel Instrument. These circular frameworks represent the celestial coordinates, including the equator, ecliptic, and meridian. They also embody the interconnectedness of various scientific knowledge.