Page:Charles Moore--Development and Character of Gothic Architecture.djvu/83

Rh level, therefore, the system is as logical as the systems of Senlis and Noyon. But the want of adequate support in the lower piers for the heavy main groups is a defect which mars this otherwise magnificent interior. It should be added that the vaulting shafts of Laon vary in magnitude in conformity with the weights they have to support the central shaft which carries the main transverse rib being the largest, those which carry the diagonal ribs smaller, and those of the longitudinal ribs the smallest.

The Cathedral of Bourges, constructed mainly during the first quarter of the thirteenth century, has also sexpartite vaults, and the disposition of its piers and shafts is peculiar though almost entirely logical. These piers are, in effect, gigantic round columns from the pavement to the springing of the vaults. As they rise through the arcade spandrels they leave something less than a quarter of their diameters projecting, and in conformity with the construction of the vault they are alternately massive and slender. Engaged in them are slender, coursed, vaulting shafts—not closely grouped according to the usual arrangement, but widely separated upon the great cylindrical surface. The adjustment of these vaulting shafts to the vaults is substantially the same as at Laon—the main shafts alone having capitals where the great ribs spring, while the supports of the longitudinal ribs rise unbroken to the higher level of the springing of these ribs. The one illogical feature of the vaulting system of Bourges is that its lesser shafts do not vary in magnitude according to their functions. With this exception there is hardly any Gothic building which exhibits greater constructive propriety; for a complete structural continuity is maintained, in both main and intermediate piers, from the pavement to the crowns of the vaulting arches.

Another mode of sexpartite vault support occurs in the Cathedral of Sens (second half of the twelfth century) and