This type of chevet as developed at Paris and Vézelay played a large part in subsequent architecture, for out of it would seem to have sprung what will be for convenience termed the buttressing-ribbed chevet. Among the more important early chevets of this type are those over the apses of Noyon[371] transepts, of Saint Remi at Reims (Fig. 64), of Saint Leu d’Esserent (Oise), and of the cathedrals of Sens, Canterbury, Noyon, and others, all probably completed before 1180. Although differing in a number of details, these apses have certain features in common. They all include beneath the chevet the preceding bay of the church, and all have the same arrangement of ribs which are so placed that the two springing from the piers next beyond the apsidal arch on either side form a transverse arch against whose crown all the others abut (Plate II-d). The object of this arrangement evidently lay in the desire of the builders to construct a distinct transverse arch between the curve of the apse and the rectangular bay included in the chevet and at the same time to employ the two ribs beyond those forming the arch, as buttresses, to offset the thrust of the remaining radiants. Thus when the rectangular bay was larger than those around the curve, as for example in the choir of Soissons cathedral (Fig. 67), the buttressing ribs were longer than the remainder of those forming the vault. This made the bay containing these two ribs precisely like one-half of a six-part vault, and as this method of vaulting was commonly used in the nave and choir of these churches this chevet was a very [Illustration: FIG. 67.--SOISSONS, CATHEDRAL.]