OF THE DIFFERENT KINDS OF ARCHES.
Q. Do the distinctions of the different styles, as they differ from each
other, depend at all upon the form of the arch?
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.
[Illustration]
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).
[Illustration]
Q. How are they formed or described?
A. The semicircular arch is described from a centre in the same line with
its spring; the stilted arch in the same manner, but the sides are carried
downwards in a straight line below the spring of the curve till they rest
upon the imposts; the segmental arch is described from a centre lower than
its spring; and the horse-shoe arch from a centre placed above its spring.
Q. During what period of time do we find these arches generally in use?
A. The semicircular arch, which is the most common, we find to have
prevailed from the time of the Romans to the close of the twelfth
century, when it became generally discarded; and we seldom meet with it
again, in its simple state, till about the middle of the sixteenth
century. It is in some degree considered as a characteristic of the
Anglo-Saxon and Norman styles. The stilted arch is chiefly found in
conjunction with the semicircular arch in the construction of Norman
vaulting over a space in plan that of a parallelogram. The segmental arch
we meet with in almost all the styles, used as an arch of construction,
and for doorway and window arches; whilst the form of the horse-shoe arch
seems, in many instances, to have been occasioned by the settlement and
inclination of the piers from which it springs.
Q. Into how many classes may the pointed arch be divided?
A. Into two, namely, the simple pointed arch described from two centres,
and the complex pointed arch described from four centres.
Q. What are the different kinds of simple pointed arches?
A. The LANCET, or acute-pointed arch; the EQUILATERAL pointed arch; and
the OBTUSE-ANGLED pointed arch.
Q. How is the lancet arch formed and described?
A. It is formed of two segments of a circle, and its centres have a radius
or line longer than the breadth of the arch, and may be described from an
acute-angled triangle. (fig. 5.).[TN-1]
Q. How is the equilateral arch formed and described?
A. From two segments of a circle; the centres of it have a radius or line
equal to the breadth of the arch, and it may be described from an
equilateral triangle. (fig. 6.)
[Illustration]
Q. How is the obtuse-angled arch formed and described?
A. Like the foregoing, it is formed from two segments of a circle, and the
centres of it have a radius shorter than the breadth of the arch; it is
described from an obtuse-angled triangle. (fig. 7.)
Q. During what period were these pointed arches in use?
A. They were all gradually introduced in the twelfth century, and
continued during the thirteenth century; after which the lancet arch
appears to have been generally discarded, though the other two prevailed
till a much later period.
Q. What are the different kinds of complex pointed arches?
A. Those commonly called the OGEE, or contrasted arch; and the TUDOR arch.
Q. How is the ogee, or contrasted arch, formed and described?
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.
[Illustration]
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.
[Illustration]
Q. What other kinds of arches are there worthy of notice?
A. Those which are called foiled arches, as the round-headed trefoil (fig.
10), the pointed trefoil (fig. 11), and the square-headed trefoil (fig.
12). The first prevailed in the latter part of the twelfth and early part
of the thirteenth century, chiefly as a heading for niches or blank
arcades; the second, used for the same purpose, we find to have prevailed
in the thirteenth century; and the latter is found in doorways of the
thirteenth, fourteenth, and fifteenth centuries. In all these the
exterior mouldings follow the same curvatures as the inner mouldings, and
are thus distinguishable from arches the heads of which are only foliated
within.
[Illustration: DOORWAY. St. Thomas’s, Oxford, circa 1250.]
[Illustration: Anglo-Saxon Doorway, Brixworth Church, Northamptonshire.
(7th cent.)]