BUILDINGS VAULTED UPON INTERSECTING ARCHES
The new system derived from the domes upon pendentives, so brilliantly
applied in Anjou and Maine in the first half of the twelfth century,
was thenceforth the normal method of the religious architect. The
admirable simplicity of the new method and its adaptability to every
class of building, from the great abbey church to the modest chapel,
sufficiently accounts for its rapid dissemination throughout Western
Europe, where religious bodies had founded innumerable abbeys, large
and small, of varying rules and orders, but all welded together by one
mighty organisation.
A long array of churches on the Angevin model rose, not only in the
neighbouring provinces--as Ste. Radegonde at Poitiers, Notre Dame de
la Coulture and the nave of St. Julien at Mans,--but farther afield
towards the south. To name only the most important--the charming
Church of Thor, dedicated to Ste. Marie du Lac, between Avignon and
the fountain of Vaucluse; that of St. Sauveur at St. Macaire, near
Bordeaux; the nave of St. André at Bordeaux, begun in 1252 on the
cupola plan, but modified and finally crowned with a groined and
ribbed vault; St. Caprais at Agen, which shows the same modifications,
and lastly, the immense brick nave of St. Étienne at Toulouse,
which measures 64 feet--all demonstrate the progression of the new
principles in the second half of the twelfth century.
[Illustration: 18. PLAN OF THE NAVE, ST. MAURICE AT ANGERS]
Towards the North the advance was no less general. Various buildings
show to what excellent account contemporary architects had turned the
system of vaults on intersecting arches, recognising its admirable
adaptability to different climates, and to the most diverse materials.
But it was reserved for Angers, the cradle of its birth, to give an
added perfection to this ingenious system.
The Church of the Ste. Trinité, on the right bank of the Maine, built
by the sons or pupils of those architects who had planned St. Maurice
for the hill on the opposite shore, marks a fresh advance in the
construction of these vaults. Like St. Maurice, it has but a single
aisle, which is divided into three bays, each as nearly as possible
square on plan. The system of vaulting takes on a greater elegance by
the insertion of a transverse arch, with its supporting shafts, in the
centre of each bay. This divides the bay into two equal parts, and,
cutting the diagonal ribs at their intersection, supports them at the
critical point.
Fig. 19 gives the plan of these vaults, the system of which was
eagerly seized upon by the Northern architects, and the great abbey
church of Noyon appears to have been the first-fruits of this new
development of the Angevin idea.
[Illustration: 19. PLAN OF THE CHURCH OF LA STE. TRINITÉ AT ANGERS]
[Illustration: 20. LONGITUDINAL SECTION OF A BAY OF LA STE. TRINITÉ AT
ANGERS]
The great abbey churches and immense cathedrals which were built from
the second half of the twelfth to the middle of the thirteenth century
attest the importance of the development carried out at Angers by
the arrangement of their own vaults in square compartments. For we
now find this system adopted in the construction of the churches or
cathedrals of Noyon, Laon, Notre Dame at Paris, Sens, and Bourges, to
name only acknowledged masterpieces of so-called Gothic.
[Illustration: 21. TRANSVERSE SECTION OF A BAY OF LA STE. TRINITÉ AT
ANGERS]
The influence of the cupola, which we established in our first
chapter, was both direct and consecutive. It was direct in churches
built with one aisle and vaulted on intersecting arches, and
consecutive in the so-called Romanesque churches, which were either
completed or modified on the new lines by the substitution of vaults
on intersecting arches of dressed stone for timber roofs. A large
number of buildings in England, Normandy, Germany, Northern Italy,
Switzerland, the Rhine Provinces, and those of Northern France bear
testimony of the highest interest to the transformations consequent on
the invention of the groined vault and its universal application.
Architects who had been trained in the great abbey schools, emboldened
by the successes of their forerunners and their own individual
experience, raised on every hand vast cathedrals, in which every known
development of the system was essayed with unequalled daring. Going
on from strength to strength, they eventually abandoned the antique
traditions, and disregarding the statical conditions which ensured
the solidity of the ancient buildings, they invented a system of
construction which is, as it were, merely a skeleton in stone, a stone
version of the timbered roof; its characteristic expression was the
permanent strut known as the _flying buttress_; its governing idea
was equilibrium, for which it provided by architectural stratagems
ingenious in the highest degree, but also extremely precarious. Its
existence or stability depends for the most part on the quality of the
materials and their degrees of resisting power, the essential organs,
by which I mean those vital _weight-carrying_ portions, the failure
of which would involve the ruin of the whole, being _outside_ the
building, and therefore exposed to all those deteriorating influences
from which the _load_ they bear, that is to say, the vaults, are
protected by walls and roof.
[Illustration: 22. SECTION OF A SINGLE-AISLED CHURCH VAULTED ON
INTERSECTING ARCHES WITH BUTTRESSES]
[Illustration: 23. SECTION OF A THREE-AISLED CHURCH VAULTED ON
INTERSECTING ARCHES WITH FLYING BUTTRESSES]
The great buildings constructed on these new principles consisted of
a central nave with two, or even four side aisles. The huge structure
depended for its light first upon low windows in the collateral
portions, secondly, upon windows at a much higher level. Hence it
became necessary to raise the vault of the central nave, and to
give it an abutment in the form of _detached semi-arches_ or flying
buttresses. The crowns of these semi-arches impinged the piers at the
planes of greatest pressure and received the collective thrust of
all the ribs, formerets, transverse and diagonal arches. Their bases
rested upon abutments, the strength of which was calculated according
to the thrust they had to meet.