sighting tube

• 观测管

sighting tube的用法和样例：

例句

1. A surveying instrument consisting of a spirit level and a sighting tube,used to measure the angle of inclination of a line from the observer to the target.
   由一个水平仪和一个观测管组成的测量工具，用来测量从观测者到目标的直线的倾斜角。