钟表业。测时仪器。控制位置的符号表示。

Horology. Timekeeping instruments. Symbolization of control positions.

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赤道式日晷，是古人利用太阳投影测时的科学仪器，由晷盘、晷针和底座组成。

An equatorial sundial is an ancient scientific equipment to tell time by using the shadow from solar projection. It consists of a sundial plate, a gnomon and a base.

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