Fig. 54.—Laon, Cathedral, Transept Triforium Chapel.
The intersection of the nave and transept was usually treated by the Romanesque builders as a distinctive vaulting bay. Occasionally, in the tunnel-vaulted churches, the builders allowed the vault of nave and transept to intersect and form a groined vault at the crossing, as, for example, in Saint Étienne at Beaugency (after 1050) (Loiret)[305] and in the church of Boisney (Eure).[306] Groined vaults are also found in this position in certain churches, like those of the Rhenish provinces, where similar vaults are used in the nave. But as a general rule, the crossing of the Romanesque church is covered by a dome resting on spherical pendentives or squinches, either unraised or else placed on a drum, which thus forms a lantern with windows to light the church interior. There is no necessity for an extended discussion of raised and unraised domes, since as far as construction is concerned they differ only in the fact that when raised on a lantern they are somewhat more difficult to support because the vaults of choir, nave, and transept no longer serve as buttressing members. The custom, however, of erecting a tower even above the raised domes offset to a large extent the thrusts which they created.
Sometimes these Romanesque crossing domes are of circular plan and supported on spherical pendentives. These are common in the school of Perigord, where examples are afforded by the cathedral of Périgueux [(Fig. 1)] or the abbey church of Solignac.[307] But the use of such domes on spherical pendentives was not confined to Perigord. They are found in Poitou and Les Charentes, in the Southwest, and even in Limousin.[308] One of the best examples, and one in which there is a circular drum below the dome, appears in the church of Le Dorat (cir. middle twelfth century) (Haute-Vienne).[309] Very occasionally, also, the flat triangular pendentive is used, as in Notre Dame at Chauvigny (Vienne).[310]
Lantern Towers
The use of a lantern tower with windows opening into the church below its roof was destined to give rise to a number of interesting vaults. That such towers existed in France as early as the sixth century, is proved by the texts of Gregory of Tours and Fortunatus, in which such lanterns are mentioned as existing over the churches of Saint Martin at Tours, the cathedrals of Clermont-Ferrand, Narbonne, and Paris, as well as at Bordeaux and Nantes,[311] while Rivoira’s contention[312] that the church of San Salvatore or del Crocifisso at Spoleto dates from the fourth century, if correct, would give an earlier though isolated Italian example of such a feature. Whatever its origin, such a lantern was a particularly pleasing feature of church construction, especially in Romanesque churches, which were without direct light in the nave and thus received a much needed addition to their interior illumination. It is not surprising, therefore, to find many of the more daring Romanesque builders including this central feature even in crossings with domes, as has already been noted. As a rule the pendentives were introduced beneath the wall of the clerestory drum which was therefore either of octagonal or circular plan. The examples of such lanterns are too numerous to cite though certain of them are worthy of some remark. In Auvergne, for example, in Notre Dame-du-Port at Clermont-Ferrand (Figs. [49], [50]), at Orcival (Puy-de-Dôme),[313] Saint Nectaire (Puy-de-Dôme),[314] and elsewhere the system of transept and crossing vaulting already described[315] made possible the introduction of windows in either the east or west walls of the central towers, or both, though rarely in those to the north or the south, where there were half or full tunnel vaults to abut the dome. In two churches of Central France, those at Bénévent-l’Abbaye (Creuse)[316] and Le Dorat (Haute Vienne),[317] the lanterns are especially beautiful. They are covered with domes raised on a drum supported upon spherical pendentives. In such churches, where there is no direct light in the nave, the lantern adds much to the appearance of an otherwise oppressively dark interior.
Ribbed Domes
Another lantern of interest is to be seen in southern France in the cathedral of Notre Dame-des-Doms at Avignon (probably cir. middle of twelfth century).[318] Here the transepts are narrower than the nave and in order to make the crossing square, a series of four arches has been thrown across between the spandrels of the nave and choir arches, Over the square thus formed is an octagonal lantern on squinches which in turn supports a circular dome with the unusual feature of a series of flat pilaster-like ribs along its-under surface. Such ribs are, of course, largely decorative and correspond to those found in the apses of many neighboring churches.[319] True ribbed domes were also used as a means of covering the crossing,[320] and this is but natural in view of the fact that such domes were quite frequently employed over circular churches, as for example Saint Sepulchre at Cambridge, and the Templar’s Chapel at Laon [(Fig. 55)],[321] while half domes of similar character appear over many apses of the Transitional period.[322]