254 COMPARATIVE ARCHITECTURE. c. Openings.- — The earlier vaulted churches have no clerestory. In the south, narrow openings with wide splays to admit light sufficed, while in the north a commencement in grouping was made, more especially in the direction of filling in the vault spandrels of the clerestory with arrangements of three and five light openings. The ante-chapels at the Church at Vezelay (1130) are generally referred to as having the earliest pointed vaults in France. Imposing western entrances are characteristic of this period. D. Roofs. — In the south, the early treatment was a tunnel vault to the nave, buttressed by half tunnels over the aisles, often in two stories, thus not admitting of a clerestory. The pointed section was sometimes used, doubtless to lessen the thrust upon the walls, and in order that the roofing slabs of stone might be carried direct upon the extrados of the vault. In the north, clerestories of increased height were obtained by means of the intersecting nave vaults (No. 100), with groin ribs (introduced in the twelfth century), whose thrust w^as taken by buttress arches concealed in the aisle roofs — a step towards the later flying but- tresses. The vault in the southern examples frequently supports the roofing slabs direct, while in the northern examples above the stone vault were constructed wooden roofs, which supported the covering independent of the vault. E. Columns. — In nave arcades, either square piers, recessed in planes, and having upon their faces half round shafts carried up to the vaulting ribs (No. 103 m-p), were employed, or columns, circular or octagonal, and reminiscent of Roman times, were used, and then the vaulting shafts start awkwardly from the abacus of their huge capitals (No. 103 d, e), imitated from the Corinthian order. The carrying up of the vaulting shafts emphasizes the division of the nave into bays. F. Mouldings. — In the south, the elegance due to classic tradition contrasts with the rough axed decoration cut upon the structural features of the Norman work. In the latter, arched jambs are formed in recessed planes (No. 102), with nook shafts plainly fluted, or cut with zigzags. Capitals are cubical blocks, either plain or carved with copies of acanthus leaves from old Roman examples (No. 103). Corbel tables, supported by plain blocks or grotesque heads, form the cornices of the walls (No. 103 B, G, j). G. Ornament. — Painted glass was not favoured in southern examples, small, clear-glazed openings being employed to set off" the opaque color decoration of the walls. Stained glass favouring large openings was gradually developed in the north. The diaper work so common in the spandrels of arches, in northern work is supposed to have arisen from the imitation, in carving, of the color pattern work, or draperies that originally occupied the
