A. It is formed of four segments of a circle, and is described from four centres, two placed within the arch on a level with the spring, and two placed on the exterior of the arch, and level with the apex or point (fig. 8); each side is composed of a double curve, the lowermost convex and the uppermost concave.
Q. When was the ogee arch introduced, and how long did it prevail?
A. It was introduced early in the fourteenth century, and continued till the close of the fifteenth century.
Q. How is the Tudor arch described?
A. From four centres; two on a level with the spring, and two at a distance from it, and below. (fig. 9.)
Q. When was the Tudor arch introduced, and why is it so called?
A. It was introduced about the middle of the fifteenth century, or perhaps earlier, but became most prevalent during the reigns of Henry the Seventh and Henry the Eighth, under the Tudor dynasty, from which it derives its name.
Q. What other kinds of arches are there worthy of notice?