A. To a certain extent the form of the arch may be considered as a criterion of style; too much dependence, however, must not be placed on this rule, inasmuch as there are many exceptions.
Q. How are arches divided generally, as to form?
A. Into the triangular-headed or straight-lined pointed arch, the round-headed arch, and the curved-pointed arch; and the latter are again subdivided.
Q. How is the triangular-headed or straight-lined pointed arch formed, and when did it prevail?
A. It may be described as formed by the two upper sides of a triangle, more or less obtuse or acute. It is generally considered as one of the characteristics of the Anglo-Saxon style, where it is often to be met with of plain and rude construction. But instances of this form of arch, though they are not frequent, are to be met with in the Norman and subsequent styles. Arches, however, of this description, of late date, may be generally known by some moulding or other feature peculiar to the style in which it is used.
Q. What different kinds of round-headed arches are there?
A. The semicircular arch (fig. 1), the stilted arch (fig. 2), the segmental arch (fig. 3), and the horse-shoe arch (fig. 4).
