When surveyors sight the summit, there is a risk they might not all measure the same point.
当测量员们看到山顶时,他们可能无法测量到同一个点。
To measure the difference in elevation between poles, surveyors used an optical level—a telescope on a level base—placed halfway between the poles.
为了测量两极之间的高程差,测量员在两极中间的一个水平基座上使用了光学水准望远镜。
The companies building the canals to transport coal needed surveyors to help them find the coal deposits worth mining as well as to determine the best courses for the canals.