1911 Encyclopedia Britannica
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.
These files are public domain.
Chisholm, Hugh, General Editor. Entry for 'Bench-Mark'. 1911 Encyclopedia Britanica. https://www.studylight.org/encyclopedias/eng/bri/b/bench-mark.html. 1910.