At Mans the arrangement of the choir is so far more remarkable in that it is extremely unusual, or indeed, in its way unique. The flying buttresses are planned in the form of a Y (see A on the plan Fig. 53), thus affording space for windows in the exterior wall, to light the vast circular ambulatory, which at Mans is of unusual importance, and surrounds the choir with a double aisle. The flying buttresses which rise above the _arcs-doubleaux_, bi-furcated (B on the plan), are over-attenuated in section; their exaggerated height and proportionate slenderness threaten to make them spring, so that it has been found necessary to bind them together by ties and iron chains. Such expedients are a sufficient criticism of the ingenious but precarious system adopted by the architects of Mans. [Illustration: 53. MANS CATHEDRAL. PLAN] [Illustration: 54. MANS CATHEDRAL. FLYING BUTTRESSES OF THE APSE] [Illustration: 55. MANS CATHEDRAL. SECTION OF THE CHOIR] The influence of the Ile-de-France in Normandy is manifest in the arrangement of choirs and apsidal chapels in Norman cathedrals of the thirteenth century. The Cathedral of Coutances, a monument of the eleventh century, was rebuilt in the early years of the thirteenth century under the impulse given by Northern France to the architecture of the period. It is in the choir that we clearly trace this influence, in the double columns of the apse, and the ingenious disposition of its collateral vaults. But the façade is purely Norman, not merely in general design, but in the details of the composition, facsimiles of which may be found in England. [Illustration: 56. COUTANCES CATHEDRAL. NORTH TOWER] The Cathedral of Dol in Brittany, one of the great churches of the thirteenth century, seems to have escaped the influences of the Northern innovation. Its general plan, its square apse lighted by large windows, the details of its architecture and ornamentation, all proclaim its affinity to the great churches which rose contemporaneously with it on either side of the Channel, in Normandy, and in England. It is very probable that it was built by the same architects or their immediate disciples, working on the more ancient methods of the Norman schools founded by Lanfranc at Canterbury towards the close of the eleventh century, on the model of those he had established in France at the famous Abbaye du Bec. CHAPTER VIII CATHEDRALS AND CHURCHES OF THE THIRTEENTH AND FOURTEENTH CENTURIES The Cathedrals of Rheims, Amiens, and Beauvais excited extraordinary enthusiasm in their time, not only in the provinces of France, but among neighbouring nations, notably in England, Belgium, Germany, Sweden, Spain, and Italy. This enthusiasm was less fervid in the provinces farthest from the royal domain; but even in these outlying districts several remarkable buildings rose in the first half of the thirteenth century, constructed on the new lines.