Judging from the style of the architecture the next oldest part of the fabric after the tower is the north aisle of the choir (generally called the lady chapel). The work here (Fig. 512) is all of a rather early first pointed style. The buttresses are plain with simple set offs, and the windows consist of two or three small pointed lights enclosed within one larger arch. The latter are low segmental pointed arches, and the haunches are raised so as to allow the small side lights to be carried as high as possible. This building is vaulted (Fig. 513) with pointed groins of first pointed section, which spring from semi-octagonal shafts with early caps, and the bosses at the intersection are carved with first pointed foliage. Above the vault there is an upper story with small two-light windows. It is approached by a wheel stair in the thickness of the west wall, entered both from the lady chapel and the nave aisle. Such upper stories over the aisles of early churches are not uncommon, as at Durham, Ely, St. Albans, Dunfermline, &c., but they generally form an upper gallery and admit light to the centre. Here the upper windows admit no light to the choir, the wall of the latter being solid. Possibly this upper chamber may have been used for a scriptorium or similar purpose. Upper stories were frequently employed for writing rooms, as at Arbuthnot and Inchcolm, the room over the chapter house of the latter being the place where Bower wrote his history. It is remarkable that this north aisle of the choir, or lady chapel, should be entirely separated from the choir by a solid wall in which there never was any opening into the aisle except the small doorway near the east end, which is of first pointed date.[42] This doorway, with its details, is shown in Fig. 514. Whether this aisle was the first part of the structure erected by Bishop Clement in order to be used as a temporary church while the remainder of the cathedral was building, or whether the choir built by him was afterwards rebuilt, the north aisle being left unchanged, it is now impossible to say. That the choir is of later date than the aisle there can scarcely be any doubt; but it does not appear to be of much later date. The same base mouldings are carried round the whole building, and the design of the east end of the choir, with its large central and two narrow side windows (see Fig. 512) and plain pinnacles, shows some features of first pointed character; but both the large window of the east end and those of the south side (see Fig. 511) point to a time about the beginning of the decorated period. The windows of the clerestory on the north side above the roof of the north aisle, with their small buttresses, are, however, of a similar early character to those of the north aisle. Whatever may have been the object in building [Illustration: FIG. 512.--Dunblane Cathedral. Choir from North-East.] [Illustration: FIG. 513.--Dunblane Cathedral. Lady Chapel.]