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.
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.
22. SECTION OF A SINGLE-AISLED CHURCH VAULTED ON INTERSECTING ARCHES WITH BUTTRESSES
