became large enough to require dividing members and to call for the use of tracery. And when they did become so, and when tracery was employed, the opening still remained really a window through a wall. When the grouped lancets of the east end were replaced by one great mullioned and traceried opening, some truly magnificent designs were indeed produced, of which that of the Presbytery of Lincoln is perhaps the grandest; yet still are these great windows generally mere openings in walls. Rarely, if ever, in England do the rib of the vault and the archivolt of the aperture come one and the same member, as they do in Amiens Cathedral.
Such are the structural characteristics of early pointed architecture in England in so far as concerns the longitudinal bays. The east ends in this architecture are usually square, perhaps because the constructive difficulties of the apsidal form were deemed too formidable, or, perhaps, from an acquired preference derived from the widespread example of the great Cistercian churches.
Not many east ends remain in their original form; but two important ones—those of Ely and Lincoln—have come down to us. They date, respectively, from the first and from the second half of the thirteenth century, and they afford a sufficient idea of such structures generally. In both of these buildings the eastern enclosure corresponds with the internal division into a wide and high central aisle and two narrower and lower side aisles. The divisions are, in each case, marked by boldly projecting buttresses, and the central compartments are surmounted by gables which follow the lines of the timber roofs. In other respects the two examples differ considerably. That of Ely (Fig. 89) has, in its central compartment, three tiers of grouped lancets—three tall ones of equal height in the lower tier, five shorter ones of graduated heights, following the line of the arch of the vault, in the second tier, and three still shorter ones of equal height, flanked on either side by a lower blind arch, in the third tier. The lower tier embraces nearly the combined height of the ground-story and the triforium, the second tier is on the clerestory level, and the third occupies the lower portion of the gable, and lights the space above the vaults beneath the timber roof. The lateral compartments
