[Illustration: FIG. 26.--Winchester Cathedral. West End of the Nave. (From Britton’s _Chronological History of English Architecture_.)] presbytery, so as to distinguish it by its richness. This class of vaulting carries out in its simplest elements the principle adopted at this period in England of making the vaulting surface more important than the ribs, and using the latter as ornaments upon the surface of the vault. The exterior of the churches is generally marked by rather heavy buttresses, crowned with small and debased-looking pinnacles. The buttresses have often a great many set-offs. In other examples buttresses are entirely omitted. The doorways vary considerably. The semi-circular arch, which is sometimes preserved in the earlier styles, is now of very frequent use, not only in doorways, but also in pier arcades and clerestories (as at Paisley and Dunkeld). Elliptic arches and three-sided door heads are also used. At this period we find indications of English influence in a few perpendicular traceries, as at Melrose Abbey, and of French influence in some Flamboyant forms, and in the three or five sided apse which frequently forms the eastern termination of the churches. Western and central towers are usual features, generally rather squat in form, and sometimes surmounted with a short spire, having numerous small lucarnes and pinnacles. Four of these towers were once finished with spires of open work resembling a crown, but the number is now reduced to two--viz., St. Giles’, Edinburgh, and King’s College, Old Aberdeen. The piers are often of a plain circular form, and the arches have frequently plain chamfers instead of mouldings. The caps of piers are peculiar and heavy, the abacus consisting of a deep series of mouldings. Grotesque ornaments and large flowers are common, and frequently of rather coarse design; but in some instances, as in the cloisters of Melrose, the ornaments are beautifully sculptured. A revival of early enrichments, such as the dog-tooth or nail-head, is a curious characteristic of this period, as it was also in the case of the late domestic architecture. Other early features are also revived, such as detached shafts, with well-marked caps and bases of early form. This is specially observable at Iona and in Argyleshire and the Western Islands, where, as already mentioned, a peculiar style prevailed. In course of time, as pointed out elsewhere,[60] the ecclesiastical elements were invaded by the features of domestic architecture, and a mixed, but picturesque, style was developed which had more of a Scottish than a Gothic aspect. Many examples of Scottish structures of the third period will be illustrated. The buildings, though comparatively small, are numerous and interesting, as they illustrate a specially Scottish branch of Gothic architecture. They consist largely of collegiate edifices, and amongst them is the well-known collegiate church of Roslyn.