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. 27.

To draw the Gothic Equilateral Arch.

—From the points A and B ([Fig. 27]), with radius A B equal to the span, describe the arcs B C and A C. By joining C to A and B we obtain an equilateral triangle from which this arch derives its name.

Fig. 28.

To draw the Gothic Lancet Arch.

—In this arch, the centres E and D ([Fig. 28]) from which the arcs are struck, are situate outside of and in a line with the points of springing A and B; thus it is constructed on an acute-angled triangle, as will be seen by joining C to A and B.

Fig. 29.