Of the eastern terminations, a number are especially interesting. One is in the church of Saint Yved at Braisne (Aisne) (1180-1216) (Plate IV-f), where there is no ambulatory and yet two chapels have been so arranged with their axes at an angle of forty-five degrees to that of the choir aisle as to form a veritable series of four radiating chapels, two on either side of the principal apse. To cover the triangular bays immediately preceding these chapels, a two-part vault corresponding to one of the diagonal halves of a simple four-part vault, is employed, while the chapel itself is covered with a three-part chevet whose crown is abutted by the half rib of the preceding bay.[451] Occasionally, too, a similar arrangement of chapels is found even where there is an ambulatory as in the church of Saint Nicaise at Reims (now destroyed) and at Upsala. Another termination of interest is that in the church of Vigan (Lot)[452] (fifteenth century) where the apse with its chevet vault is west of the transept, into which it opens through its farthest bay while from the transept itself open five small chapels, a unique arrangement. A third eastern termination of especial interest is that of the church of the Jacobins at Toulouse (Haute-Garonne) (Fig. 89 and Plate IV-g). Here there is a row of central piers the length of the church and the apse embraces the double nave thus formed. This apse the builders have subdivided into a series of triangular bays by arches springing from a pier at the center of its diameter. Each of these is again subdivided like the triangular ambulatory bays of Le Mans cathedral. This completes a vault of very beautiful character. It is not, however, an original product in Toulouse, for the crypt of Canterbury cathedral (1175-1184) affords a similar vault of earlier date and others on a circular plan may be seen in a number of English Chapter Houses. THE VAULTING OF RADIATING CHAPELS [Illustration: FIG. 89.--TOULOUSE, CHURCH OF THE JACOBINS.] As for the radiating chapels, they were added to the ambulatory with the evident purpose of affording more space for altars especially in the great pilgrimage churches.[453] At the beginning of the eleventh century, three such chapels had already been built off the ambulatory of Saint Martin at Tours and only slightly later in date are those in La Couture at Le Mans followed by those of a great number of churches of the eleventh and twelfth centuries.[454] Nor are such chapels found only in churches with ambulatories. They frequently open directly off the apse, sometimes being merely recesses in the thickness of the outer wall[455] but more often extending beyond it.[456] Ordinarily, however, churches with radiating chapels have an ambulatory as well; but even so, there are occasional examples of chapels lying entirely within the thickness of the exterior wall[457] in which cases they are merely half-domed niches.