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

by George G. André

To draw the Gothic Obtuse Arch.

—This arch, called sometimes the Drop-Arch, is constructed on an obtuse-angled triangle; the centres E and D ([Fig. 29]) being situate below and within the points of springing A and B.

Fig. 30.

To draw the Gothic Tudor Arch.

—On the line of springing A B ([Fig. 30]), take any two points as F and G, so that A F is equal to G B. Draw F E and G D cutting each other on the bisecting line through C; from F and G, with radius F A or G B, describe the short arcs, and from E and D, with radius E C or D C, describe the arcs meeting in C.

Fig. 31.

To draw the Moorish Horse-Shoe Arch.

—The centres E and D ([Fig. 31]) from which the arcs forming this arch are struck, are situate above and within the points of springing A and B. One of the most graceful forms of this arch is obtained when the height of the points E and D above the line of springing and their distance from the bisecting line through C are equal to one-third of the span A B.