+ARCHITECTURAL DETAILS.+ The details of French Romanesque architecture varied considerably in the several provinces, according as classic, Byzantine, or local influences prevailed. Except in a few of the Aquitanian churches, the round arch was universal. The walls were heavy and built of rubble between facings of stones of moderate size dressed with the axe. Windows and doors were widely splayed to diminish the obstruction of the massive walls, and were treated with jamb-shafts and recessed arches. These were usually formed with large cylindrical mouldings, richly carved with leaf ornaments, zigzags, billets, and grotesques. Figure-sculpture was more generally used in the South than in the North. The interior piers were sometimes cylindrical, but more often clustered, and where square bays of four-part or six-part vaulting were employed, the piers were alternately lighter and heavier. Each shaft had its independent capital either of the block type or of a form resembling somewhat that of the Corinthian order. During the eleventh century it became customary to carry up to the main vaulting one or more shafts of the compound pier to support the vaulting ribs. Thus the division of the nave into _bays_ was accentuated, while at the same time the horizontal three-fold division of the height by a well-defined triforium between the pier-arches and clearstory began to be likewise emphasized. +VAULTING.+ The vaulting was also divided into bays by transverse ribs, and where it was groined the groins themselves began in the twelfth century to be marked by groin-ribs. These were constructed independently of the vaulting, and the four or six compartments of each vaulting-bay were then built in, the ribs serving, in part at least, to support the centrings for this purpose. This far-reaching principle, already applied by the Romans in their concrete vaults (see p. 84), appears as a re-discovery, or rather an independent invention, of the builders of Normandy at the close of the eleventh century. The flying buttress was a later invention; in the round-arched buildings of the eleventh and twelfth centuries the buttressing was mainly internal, and was incomplete and timid in its arrangement. +EXTERIORS.+ The exteriors were on this account plain and flat. The windows were small, the mouldings simple, and towers were rarely combined with the body of the church until after the beginning of the twelfth century. Then they appeared as mere belfries of moderate height, with pyramidal roofs and effectively arranged openings, the germs of the noble Gothic spires of later times. Externally the western porches and portals were the most important features of the design, producing an imposing effect by their massive arches, clustered piers, richly carved mouldings, and deep shadows.