1911 Encyclopædia Britannica/Bench-mark

From Wikisource
Jump to: navigation, search

BENCH-MARK, a surveyor’s mark cut in stone or some durable material, to indicate a point in a line of levels for the determination of altitudes over a given district. The name is taken from the “angle-iron” which is inserted in the horizontal incision as a “bench” or support for the levelling staff. The mark of the “broad-arrow” is generally incised with the bench-mark so that the horizontal bar passes through its apex.