the windows in the north wall. The caps are carved and have square abaci. The large outer arch of each window is of square section and perfectly plain, having only a small chamfer on the edge, and a label moulding. Each window is divided into two openings by a single central shaft, having a carved cap and broad square abacus, on which rest the two plain pointed arches of the inner openings. The shield above is pierced [Illustration: FIG. 498.--Holyrood Abbey. Upper Part of Tower.] with a bold quatrefoil. The jambs and central shaft have a moulded band in the middle of their height, and the windows are built up solid to that level, one of the mouldings of the band being carried across as a cornice; but this is probably a late insertion. On each external angle of the tower a large nook shaft is carried up, and finished with a cap on top and base at bottom. As above mentioned, the two western piers of the crossing (see Fig. 493) are still standing. They consist of shafts similar to those of the main piers of the nave, but considerably larger, and are carried up to the same height as the vaulting shafts of the nave, where they have similar caps and a bold pointed arch thrown across the nave. Within this arch there has been erected, in modern times, a large traceried window. The spaces below the window and across the side aisles have been built up with fragments of the demolished structure, and a window is thus formed at the east end of each aisle. During the fifteenth century the church has evidently undergone a thorough repair. It is thought that this was undertaken by Abbot Crawford, who presided over the abbey from about 1460 to 1483. The work executed at this time consisted of the addition of seven buttresses on the north side and several buttresses on the south side of the aisles. Those on the north side (see Fig. 486) are large, and may either enclose the old buttresses, or have been substituted for them. They have a set-off near the centre, above which each contains an elaborately ornamented and canopied niche. Beneath and above the niche there are carved panels which have contained angels and shields, with coats of arms. The arms of Abbot Crawford are said to have been carved on the panels, but they are now too much decayed to be distinguishable. Above the upper panels the buttresses are continued with several set-offs, and finished with a small square pinnacle. The pinnacles have been crocheted and terminated with a carved finial, but they are now greatly wasted away. There were, doubtless, flying arches from the above buttresses to the clerestory (see their springing in Fig. 484), but they must have fallen with the roof.