grand summing-up of the principles and constructive forms that had been gradually taking shape since the beginning of the twelfth century. 
FIG. 38. At first glance it may appear that the longitudinal rib is not so much stilted as are those of the buildings before noticed; but this is only because the capitals of their shafts are not situated at the true impost level. The arch is really stilted above these capitals, so that the vault surfaces continue to rise vertically for a considerable height above the springing of the great ribs, whose pressures fall directly upon the pier (Fig. 38), as in the previous examples.
The main vaulting shaft is now, for the first time in a quadripartite vaulting system, perfectly continuous from the pavement; that is to say, it is not sustained by a separate member in the lower pier, as at Paris, Chartres, and Reims; and it is not only continuous, but it also has the same diameter throughout. The shafts of the diagonal ribs rest upon the great pier capital as before, and those of the longitudinal ribs are brought down to the triforium ledge, uniting the clerestory and triforium into one composition in a manner which finds earlier illustration in the choirs of St. Germain des Prés and St. Remi of Reims, and further development in St. Denis and Sees. The abaci of the capitals are everywhere adjusted in form to the sections of the members which they carry; and those of the vaulting shafts are set in the directions of the ribs which they sustain.
