The sphere is mounted by its poles (corresponding to the celestial poles) on a metal axis, and can rotate around it.
整个铜球可以绕一根金属轴转动，转动一周代表一个昼夜。
The gnomon in the middle is perpendicular to the plate, parallel to the earth's axis, and points to the celestial North Pole (near the north Star).
晷针垂直于晷盘，平行于地轴，指向天北极(北极星附近)。
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