#The Choir.#--The exterior of the north side of the choir is almost identical with that of the south; but there are some points of difference between the four earlier bays east of the transept and the four later ones west of it. In particular, in the four eastern bays the triforium passage runs outside instead of inside the building. The clerestory windows are recessed, and in front of them, running flush with the buttresses, is a screen of three divisions to each bay (see illustration, p. 62). The triforium passage, hidden by the roof of the aisle, runs below the screen and the windows, and between the two. The mullions dividing the screen run straight up to the battlement. The tops of the divisions are ornamented with cusped arches of open stonework. There is a transom crossing the mullions of the screen about one-third of the way up. It is difficult to say what was the object of this screen. It must have been included in the original design, and so cannot have been added afterwards to strengthen the walls. Whether it was a merely decorative experiment or an architectural device for the purpose of allowing the walls to be pierced with very large windows for the display of glass cannot now be decided. The effect from the outside is not good. The mullions break the surface into too many vertical lines, and, with the transom, take away from the dignity and purity of outline of the exterior. Inside, whether by a lucky chance or not, this screen, by darkening the clerestory windows, has greatly added to the effect of the wall of glass at the east end. There are also slight points of difference in the clerestory windows, showing the transitional character of those in the four eastern bays. The windows of the aisle are delicately moulded with capitals to their shafts, and are ornamented with a crocketed gable, ogee-shaped and topped with a prominent finial rising just above the battlements of the aisle. These battlements are pierced with cusped circles, below them is a cornice ornamented with foliage. The buttresses of the aisles are decorated with gargoyles and crowned with pinnacles of a considerable size with crocketed spires and finials. The front of these pinnacles is ornamented with characteristic Perpendicular panelling. The buttresses of the main wall are thin and plain, and, with the pinnacles, much resemble those of the nave. The battlements are of pierced stonework of a common Perpendicular pattern. The eastern transepts do not project beyond the aisles. Their fronts contain very long windows of five lights, each with three transoms. The southern one has strong buttresses ornamented with panelling, and gargoyles at the corners. The northern is much plainer. Their side windows are like those of the clerestory. Britton conjectures that the unfinished state of the stonework on the north side of the choir beneath the window shows that a cloister or other low building was intended in this part, which was never executed.