Gothic Architecture in France
The structural innovations of Gothic architecture were made chiefly in the 12th century. First in importance was the ribbed groin vault. The preceding Romanesque style in Lombardy had constructed vaults with three pairs of semicircular arches, or ribs. One pair, the transverse ribs, spanned the nave of the church and divided it into square bays or compartments; one pair, the wall ribs, ran from pier to pier and marked the sides of the square; and one pair, the diagonal ribs, divided the bay into four triangular segments. This idea had been adopted and modified in the Norman Romanesque style in the 11th century.
In the Lombard system, if all the semicircular ribs started to curve at the same level, the crown, or apex, of the diagonal ribs would be higher than the crown of the transverse ribs, since a diagonal is longer than the side of a square. Also, the Lombard vaults were thick and heavy. The Gothic wanted lighter vaults that could be constructed over areas of any shape, and ribs whose crowns would all be at the same level. Two innovations achieved these ends. First, the ribs were pointed where added height was necessary. Pointing appears first in the wall and transverse ribs, not in the diagonal ribs. The pointed arch in itself could produce a vault with level crowns, but since the Gothic preferred rectangular to square bays, the wall ribs would have been very sharply pointed indeed. Therefore the Gothic builders stilted the wall rib; that is, its springing, the point at which it begins to curve, was raised above the springing of the transverse and diagonal ribs.
With these innovations, vaults could cover rectangular bays in the nave, square bays in the aisles, trapezoidal ones in the ambulatory, and the semicircular apse itself. In facts, whether the ribs support the vault is still debated. They certainly dramatize it by emphasizing its shape and the lines of its intersecting surfaces. Lombard vaults had been as much as two feet (0.6 meter) thick. When the Gothic matured in the 13th century, the vaults had become thin shells only four to six inches (about 10–15 cm) thick. The square bays of Lombard vaulting were divided into four triangles. The Normans altered these quadripartite vaults to sexpartite by adding another transverse rib midway between the main transverse ribs. Gothic builders of the 12th century preferred sexpartite vaults, but the 13th-century builders returned to the quadripartite.
Ribbed vaults need vertical support from a membered pier with a colonnette or pilaster to offer visual support for each rib it carries. These piers had been part of the Lombard system, but they were bulky. At first, the Gothic replaced them with round columns, with a group of colonnettes above them, as in Notre Dame Cathedral, Paris. But the colonnettes were strongly vertical and the round columns less so. Hence in the mature Gothic nave of Amiens Cathedral, four colonnettes were attached to a slender central column. One of these seemed to support the vaults in the aisle, two the arches of the nave arcade, and the fourth the main transverse rib. In Amiens the colonnettes under the wall ribs terminate at the bottom of the triforium, the middle story in a Gothic church, and those under the diagonal ribs terminate at the capitals of the nave arcade. Since the colonnettes merely symbolize their support of the ribs, the complete set need not descend to the floor.
Gothic vaults, especially when they are as high as those in many French cathedrals, require extensive buttressing to resist the lateral pressure or thrust they generate. The pier buttress, or tower buttress, is like a section of wall jutting out from the building opposite each pier. By sheer weight, it overcomes the thrust exerted near its top. Its outer surface has several offsets so that the buttress is thicker at the bottom than at the top. If, like the Ste-Chapelle, Paris, a church has no side aisles, tower buttresses solve the problem. But where side aisles exist, flying buttresses are needed to transmit the thrust of the nave vaults over the aisle roof to the tower buttress. The flying buttress, unique to Gothic architecture, is a half arch resting on the tower buttress and carrying a row of stones at right angles to the line of thrust. In the mature Gothic there may be two fliers, the lower taking care of the nave vault and the upper the wind pressure on the roof.
These structural elements allow the Gothic plan to become a series of isolated points. Bearing walls disappear; their place is taken by stained glass, which in turn needs support against wind. The large windows are divided by vertical bars of stone called mullions, which hold a network of arches or tracery.
The buttresses topped by tapering pinnacles dramatize the vertical movement that reaches its apex in the towers of the front. These towers were designed to carry spires that point to heaven, though spires were not always built. Chartres Cathedral has two, but Notre-Dame in Paris, Reims, and Amiens cathedrals have none.
As one walks around outside a Gothic cathedral, each part of the interior becomes visible. The nave rises a full story above the aisle roofs. The transepts that convert the plan of the church into a cross separate the nave from the choir. The semicircular apse is ringed by the ambulatory, which gives access to the radiating chapels. Each of these parts had its function. The nave was the area for the congregation, while the choir housed the clergy. The apse was the sanctuary, and the radiating chapels provided for smaller services and contained some of the sacred relics so vital to the Middle Ages. The aisles allowed the congregation to move about but they also provided a path for the processions important to the liturgy. These elements existed in the earlier Romanesque cathedrals, but were conceived as self-contained and separate units. In the Gothic churches, the plan allows the volumes to merge, the space to flow from nave to aisles.
The continuity of the piers ensures that the interior of the Gothic church, like the exterior, is vertical. In the 12th century there were often four stories: the nave arcade between the nave and the aisles, a gallery, a triforium corresponding to the aisle roof, and a clerestory to light the nave. Mature Gothic cathedrals like Chartres and Amiens omit the gallery. This did not mean that the vaults were lower. On the contrary, the Gothic craved and dramatized height. The vaults of many French cathedrals are more than 100 feet (about 30 meters) above the pavement, those of Beauvais soaring to about 157 feet (about 48 meters).
The number of Gothic cathedrals built in northern France during the 12th and 13th centuries is remarkable. Even relatively small cities rivaled one another in the size and height of their churches. Though the churches were paid for by the bishop, the townsfolk took pride in them. At Chartres, they contributed their labor in hauling stone to the building, though the actual construction was the task of skilled masons working under an architect's direction. By the end of the 13th century, the wave of cathedral building ebbed, and many were left not quite complete.
The 14th century was a barren time in French architecture, partly because the Hundred Years' War between France and England was fought on French soil. In the 15th century, however, Gothic revived in the Flamboyant style, so called because of the flamelike reversed curves of its tracery, possibly influenced by the English Decorated style. The Flamboyant is best seen in parish churches like St-Maclou (1541), Rouen, with its bowed front. The Flamboyant vaults are more complex than the earlier ones, and the piers often have moldings that run without a capital from the arches down to the base.