The south transept of Soissons Cathedral was evidently suggested by Noyon. This is apparent in the adoption of the two-storied side aisle and in the semi-circular plan. But the method of vaulting common to both churches has a greater refinement at Soissons. Reduced to its simplest expression of strength by the attenuation of its skeleton, the vault still exercises its full thrust on those parts which rise above the upper gallery. The architect of Soissons was not content, like his brother of Noyon, to support the vault laterally by interior arches collaborating with the _arcs-doubleaux_ of the triforium, and reinforced by an abutment impinging on the wall of the central nave. To him the idea occurred of detached semi-arches in open air, springing from above the roof of the triforium and its buttresses and marking each bay. Thus was born the _flying buttress_, a feature frankly emphasising its special aim and function, namely, to meet the thrust of the main vault at its points of concentration. [Illustration:30. SOISSONS CATHEDRAL. SOUTH TRANSEPT. SECTION OF FLYING BUTTRESS] [Illustration: 31. PERSPECTIVE VIEW OF SOUTH TRANSEPT, SOISSONS CATHEDRAL[8]] [8] These flying buttresses, in themselves insufficient for the task laid upon them, and worn by the destructive action of the weather, were pushed entirely out of shape by the constant pressure from within, the thrust of the vault being aggravated by the circular plan of the building, while the vaults themselves became dislocated by reason of their insufficient abutments. It became necessary to reconstruct the buttresses in 1880, to avert the total collapse of the south transept. The reconstruction of these flying buttresses, and of many others of the same period, furnishes us with a criticism _ad hominem_ upon the system. The flying buttress, in combination with the intersecting arch, gave birth to a new system of construction, a system on which were raised vast buildings which compel our admiration and demand our careful study, but should not invite our imitation. They are monuments to the ingenuity of the twelfth and thirteenth century architect, but no less are they beacons warning against the perils of a rationalism--more apparent than real--which their authors carried to its extreme limits, casting to the winds all traditional principles, and consequently all authority. It would seem as though the architects of this period, emboldened by such achievements as the churches of Noyon, Soissons, Laon, Paris, Sens, and Bourges, and spurred by professional emulation, went on from one feat of daring to another, passing from the triumphs of Rheims, Amiens, and Mans to the supreme architectural folly of Beauvais, and creating monuments no less amazing in dimension than in the statical problems grappled with, if not always solved. CHAPTER VI CHURCHES AND CATHEDRALS OF THE TWELFTH AND THIRTEENTH CENTURIES