古代测量正午日影长度以确定方向、节气和时刻的天文仪器【天】gnomon and ruler sundial

• 灵台上有浑仪、圭表、地动仪等观测仪器。

  There are observational instruments such as an armillary sphere, gnomon and ruler sundial, and seismometer on the coffin platform.

• 与其他圭表不同，这件圭表适用的地理纬度是固定的。

  In contrast to other gnomon and ruler sundials, this gnomon and ruler sundial can only be used at a fixed latitude.

借指准则principle