In the midday, when the gnomon's shadow was cast over the stone plate, they could read the length of the shadow directly from the ruler.
正午时，表影投在石板上，古人就能直接读出表影的长度值。
The invention relates to a stone plate, which comprises the following parts: thin stone plate, strip groove on the back of thin stone plate, rib reinforcement inserted in the strip groove.
一种石质板材，包括一石材薄板，在该石材薄板的背面设有条形沟槽，该条形沟槽内嵌设有加强筋。
The invention relates to a stone plate, which comprises the following parts: thin stone plate, strip groove on the back of thin stone plate, rib reinforcement inserted in the strip groove.
一种石质板材，包括一石材薄板，在该石材薄板的背面设有条形沟槽，该条形沟槽内嵌设有加强筋。
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