The armillary sphere on the top level comprised 12 rings in three layers, each of the rings being marked with a scale. From the armillary sphere one could directly read off the positions of the 24 Solar Terms, and by looking through a sighting tube one could find the star or planet one wished to observe, and define its coordinates.
最上層的渾儀一共有三層十二個環，上面都有刻度，由渾儀上可以直接對應出二十四節氣的位置，極為實用。而由窺管，可以直接讀出所觀測的星球所在，進而定出它的座標。