Sometime in the fifteenth century the third bay from the east, in each aisle, was altered and a large Perpendicular window inserted in order to admit more light to the sanctuary. During the restoration of the cathedral these later windows were removed, and replaced by careful copies of the other Early English windows. The basement is composed of bold mouldings with a plain wall equivalent in height to the internal wall arcade. Over this, a string-course runs uninterruptedly round the choir just below the windows. [Illustration: THE SOUTH DOOR. (See p. 21.) _A. Pumphrey, Photo._] Each compartment has an arcade of four lancet-shaped divisions, the external ones blank; while the internal divisions (which are wider than the others) form the window. The slender, banded, shafts are detached, which is rather unusual, and have moulded bases and capitals. The bands divide the shafts into unequal lengths, the lower portion being the shorter. The arch mouldings are good. Owing to the fact that the blank arches are more acutely pointed, their outer mouldings terminate higher than the mouldings of the internal arches. Towards the east end small heads, and bosses of foliage, ornament the junction of these mouldings. Above these the cornice and parapet rest upon blocks bearing the nail-head ornament. [Illustration: ELEVATION OF EAST END.] The second bay from the east is divided into three equal spaces, with a very narrow acute angle on the right. A series of fine gabled buttresses gives relief to the exterior of the choir on each side. The windows of the #Clerestory# have very rich mouldings, and also afford fine examples of flowing tracery. Each bay has an arch with three divisions, the central one higher and wider than the others. On this side only--the north--the base is ornamented with trefoils. There is a cornice above the windows extending from the tower to the east end. It is richly decorated with heads and the ball-flower ornament which is characteristic of fourteenth-century work. It is broken here and there by gargoyles projecting almost three feet from the wall. The parapet makes but a poor show in comparison with the rich windows and cornice. As the choir never had a groined ceiling there was no necessity for flying buttresses, and their absence gives the clerestory a very monotonous flat effect. This is further intensified by the window tracery being level with the wall, the architraves having no depth of moulding round them. Some years ago the aisles and clerestory were skilfully refaced, and consequently the exteriors have a very modern appearance.