The School of Bourgogne
It is most unfortunate for a study of the school of Bourgogne that the mother church at Cluny (Saône-et-Loire) should have been almost totally destroyed in the French Revolution. This great church was begun in 1089 and must have been finished in 1125, for the nave vaults fell in that year and were rebuilt before the final consecration in IIVO. What its original vaulting system was is difficult to say. Reber[93] says that it was probably vaulted like the churches of Auvergne with inner aisles in two stories, but Rivoira[94] states that both the nave and aisles had tunnel vaults on transverse pointed arches. The exterior view,[95] and the model which fortunately remains, would correspond with either arrangement.[96] The important facts to note are that the nave had a clerestory, and that the nave vault was strengthened on the exterior by carrying up the clerestory walls to exert a downward pressure at its haunch, a most important structural advance over the exterior wall of Saint Benoît-sur-Loire.[97]
Fig. 14.—Paray-le-Monial, Abbey Church.
The developed system of Bourgogne may be seen to advantage in the abbey church of Paray-le-Monial (Saône-et-Loire) (Figs. 14, 15), which dates from the early twelfth century and is thus only slightly later than Cluny itself. Its nave is wider and loftier than any yet seen in which a tunnel vault was used, though not equal in size to that at Cluny, which was thirty-two feet wide and ninety-eight feet high. All the structural arches are pointed, but those used for windows, doors and decoration are still round headed.[98] The clerestory, while it has only moderately large windows, is so high above the ground as to render the support of the vaults above it exceptionally difficult. This difficulty was overcome, first by giving the vault a pointed section and thus reducing the thrust; second, by building as light a web as possible and covering it with a wooden roof; third, by using tie-rods of wood or metal, running along near the impost of the vault in the thickness of the walls, thus to a certain extent concentrating the pressure upon the piers; and, finally, as has already been stated, by carrying the exterior walls of the church to a point considerably above the window heads [(Fig. 15)], thus obtaining a downward pressure which offsets the outward thrusts.
Fig. 15.—Paray-le-Monial, Abbey Church.
The side aisles of the school of Bourgogne are also worthy of mention. They are usually covered with groined vaults, in many cases of slightly domical form. Whether this method came directly from Lombardy where there exist early examples of its use, or whether it came in through the influence of Poitou and Auvergne which had come into close contact with Carolingian architecture, is an open question. It seems quite likely, however, that, since the Byzantine builders developed this type and transmitted it to the Carolingian builders of the Rhine valley, it should have passed from there into France and spread over the three northern-central schools as it did over Lombardy. Regardless of its origin, it became the standard type in all the important churches of the Cluniac region. Occasionally, as at Souvigny (Allier) (possibly eleventh century), the enclosing arches are of stilted round headed form, a type which is also found as far north as Vézelay (Yonne) La Madeleine (after 1140) [(Fig. 16)]. Neither of these churches, however, is near the center of the school,[99] and the pointed structural arch as used in the abbey church of Paray-le-Monial [(Fig. 14)] is the common form.
The system employed in Bourgogne marks the highest development attained in the use of a tunnel vault running the length of the nave. In the Ile-de-France a few instances might be cited[100] in which a system like one of those already described was used, and the same is true of certain Romanesque churches outside of France, but in none of them is any new structural method introduced. The tunnel vault was even used occasionally as late as the thirteenth century,[101] but the examples are generally small and insignificant.