The Draughtsman's Handbook of Plan and Map Drawing / Including instructions for the preparation of engineering, architectural, and mechanical drawings.

by George G. André

Fig. 2.

Fig. 1.

Fig. 2.

To erect a Perpendicular to a given Straight Line.

—Let it be required to erect a line perpendicular to the point B ([Fig. 2]) in the line A B. From any point C above the line, with radius B C, describe an arc as A B D; join A C and produce the line until it cuts the arc in D, and join D B; then will D B be perpendicular to A B.

Fig. 3.