compass prime vertical [航] [水运] 罗盘的东西圈
The deviation from vertical, irrespective of compass direction, expressed in degrees.
偏离垂直方向的角度，与指南针方向无关，以度数来表示。
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It contains a telescope, a compass, and a protractor, and it's used to measure horizontal and vertical angles.
一个指南针，一个测角器，它用来测量水平和垂直的角。
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