Because of the close resemblance in plan and structure between them, the transept was vaulted like the nave in by far the larger number of instances. Thus in the Romanesque schools, where the nave was tunnel vaulted, similar vaults were generally placed above the transept as well. They were, moreover, well suited to this position, especially where there were no transept aisles, for the outer walls running down to the ground afforded them excellent support and also provided space for windows of considerable size. It is not surprising, therefore, to find the tunnel-vaulted transept the standard in Romanesque church architecture, an example appearing even as far north as Jedburgh Abbey in Scotland, although this was a church of the Norman school in which the nave was probably originally roofed with wood.[282] Even in the school of Perigord, where the naves are domed, the transept is frequently covered with a tunnel vault as, for example, in the churches of Souillac (Lot), Tremolac (Dordogne), and Vieux Mareuil (Dordogne), in the cathedral of AngoulÊme, and perhaps originally in the cathedral of Saint Front at PÉrigueux.[283] Occasionally, however, other forms displace the tunnel vault in transept construction.

One of these appears in the abbey church of Cluny (SaÔne-et-Loire) (early twelfth century). Here the bays of the transept, corresponding to the side aisles of the church are tunnel vaulted, but beyond these, there are two projecting bays, the inner one square and covered by an octagonal dome on trumpet squinches, the outer covered with a tunnel vault at a lower level[284] than that over the two bays adjoining the crossing. Above the dome rises an octagonal tower and spire, and the whole composition of this bay shows that it was intended to be a flanking tower like those to be seen at AngoulÊme, TrÉguier (CÔtes-du-Nord), and Exeter cathedrals. For such a tower, a dome is more suitable than a tunnel vault, because it exerts less outward thrust. This is also better distributed.

A more original method of transept vaulting is to be seen in certain churches of the school of Auvergne, among them Notre Dame-du-Port at Clermont-Ferrand (Puy-de-DÔme) (eleventh and twelfth century) (Figs. 49, 50) and Saint Étienne at Nevers (NiÈvre) (cir. 1097).[285] Here each arm of the transept is divided into two distinct vaulting bays by a transverse arch continuing the line of the outer wall of the church. All the projecting portion is then covered by a tunnel vault, while that bay which corresponds to a continuation of the side aisles is covered by a half tunnel vault, its axis at right angles to the transept proper and rising from above the crown of the intermediate transverse arch to the springing of the crossing dome (Figs. 49-50). Such a vault has much to commend it, for it is most logical in affording excellent abutment for the dome, and at the same time it receives abutment from the tunnel vault of the outer transept bay. Curiously enough, one church of the school, namely that at Orcival (Puy-de-DÔme) (twelfth century),[286] while following the main lines laid down by the vaults just described, differs from them in having full tunnel vaults instead of half tunnels abutting the dome. This is a less satisfactory form in that these vault have to be excessively high in order to bring their thrusts to the proper level, but they do possess the advantage of providing excellent window space above the transept roofs.

Transepts with Ribbed Vaulting
Five-Part Ribbed Vaults

With the introduction of ribbed vaulting, examples of six-part vaults, four-part vaults of rectangular and square plan and many forms of complicated vaulting are to be found in the transept exactly as they have been in the nave. Only those vaults which are unusual in character will therefore be discussed. Of these the most important is the five-part rectangular vault sometimes used as a termination of the transept arm. From its appearance in Normandy, and its evident relation to sexpartite vaulting, this method may be assumed to have arisen there. The Abbaye-aux-Dames at Caen (early twelfth century) affords an example of such a vault. It was evidently employed to subdivide the end walls into bays similar to those in the remainder of the church, and thus provide a uniform elevation and window arrangement throughout the edifice. In spite of its uniformity the arrangement is an awkward one, for it brings a pier directly in the center of the transept wall where it would be more natural to find a door. The five-part vault did not, therefore, become a general method of transept termination, though there is a very fine example of its survival in the church of Saint Urbain at Troyes (Aube) (cir. 1262-1300). It may even be that the desire for a regular elevation of the bays led to the subdivision of the transept by a row of central piers, such as those in the large church at Saint Nicolas-du-Port (Meurthe-et-Moselle) (sixteenth century)[287] and in a number of smaller examples, some of them of earlier date.[288]

Square Chevets

Such a vault as that just described was, in a way, a sort of square chevet.[289] It was built to provide a better arrangement of windows in the terminal wall than would be possible beneath the transverse cell of a regular four-or six-part vault. Nor was its use confined to the transept for it is found with a varying number of cells at the end of the nave and choir as well. Such Norman churches as Saint Georges at Saint Martin-de-Boscherville (Fig. 51), Saint Étienne at Caen and Saint Cross at Winchester (choir cir. 1135-1189) are examples of this,[290] while the vaults of the transepts of Limburg Cathedral[291] (1235) and that of the chapter house at Boscherville (Fig. 52) resemble a chevet even more closely in that all but one of their severies are subdivided. When the ribs all rise from the same level, the appearance of such a vault is pleasing, but when,—as in the nave of Boscherville (Fig. 51),[292]—the intermediate ribs are shortened,

the effect is very unsatisfactory, though this shortening of the ribs probably had a structural advantage in preventing the light from being partly cut off, or the windows partly concealed by the radiants and the masonry above them.

Vaulting of Semicircular Transepts

The vaulting of the transept naturally differs from that in the nave when the former is given a semicircular termination. In Romanesque transepts of this type, the vaults are in the form either of simple half domes, or of tunnel vaults ending in such domes, according as the transept arms are lengthened or left merely in the form of apses. Many churches of both these types, but usually of small size, are to be found in southern France,[293] while others appear in Italy and still others in the north of Europe,[294] where such a church as that of Rolduc (Belgium) was considered by its builders as built in a Lombard manner, “scemate longo-bardico,”[295] indicating that the semicircular transept was thought, at least, to be of Lombard origin. The most highly developed transepts of this tunnel-vaulted, half-domed type are probably those in the church of Saint Mary of the Capitol at Cologne, where a groin-vaulted ambulatory is found around each transept apse. Somewhat similar in plan are the transepts of Tournai cathedral in Belgium (between cir. 1110-1170) (Fig. 53), except that here the surrounding aisle is very narrow, and, more important still, the half dome is replaced by a clumsy chevet vault with very heavy ribs, their haunches raised to support a series of ramping and contracting tunnel vaults. This construction is very similar to the framework of such a dome as that of the Baptistery at Florence. Nor is it without advantages, since it greatly reduces the vault thrusts and therefore renders unnecessary the use of flying-buttresses,[296] and at the same time permits the windows to rise above the level of its impost. The next semicircular transept of importance is that of Noyon cathedral

(cir. 1140),[297] where there is a developed chevet of what will later be called the buttressing ribbed type.[298] More developed still is the south transept of Soissons cathedral (1176-1207), which possesses an ambulatory in two stories with three bays of trapezoidal four-part ribbed vaults corresponding to each principal vaulting bay. The transept proper is covered by a rectangular vault[299] and a broken-ribbed chevet with very broad window cells. Other examples of semicircular transepts could be cited, both of the Romanesque and Gothic periods,[300] but either they do not present any vaulting forms not already discussed or they will be described in connection with the apse proper. That the plan had a long lease of life, if not a very extensive usage, is shown by the fact that it appears in such seventeenth century churches as that of the LycÉe Corneille at Rouen (beg. cir. 1614),[301] and is found in numerous Renaissance churches in which the vaulting returns to the earlier tunnel and half-dome forms.[302]

The Vaults of Transept Aisles and Chapels

As the transept developed in importance aisles were added, sometimes merely along the east walls, but often along the west as well,[303] and even across the ends, especially in churches where such tribunes provided for a continuation of the triforium gallery.[304] In such transepts the side aisles are vaulted just as those belonging to naves of a corresponding period, and therefore require no discussion here. More important are the chapels which open off of the transept, usually from the eastern wall. In general these consist of a semicircular apse either with or without one or more preceding bays. During the Romanesque period such chapels were generally covered with a half dome sometimes preceded by a tunnel vault as in Saint Georges-de-Boscherville, while after the introduction of ribbed vaults, these and the chevet replace the tunnel vaults and half domes in their respective positions. Sometimes the chapels are square, especially in Cistercian churches. They are then covered either with tunnel vaults, as in Kirkstall Abbey, or with ribbed vaults in the Gothic period. Usually all these radiating chapels are but one story in height, but in the cathedral of Laon, two beautiful chapels more than a semicircle in plan and two stories in height appear, one at the east end of both the north and south aisles of the transept (Fig. 54). These chapels are vaulted with seven-part chevets, and form, with the aisles and tribunes preceding them, veritable churches inside of the cathedral. Chapels of similar character, but practically a full circle in plan and vaulted with a double chevet, are also to be seen in the two lower, stories of the transept of Soissons cathedral. They open off of the aisles and galleries through three slender arches, and the view into them from the transept proper affords one of the finest examples of Gothic perspective.

Crossing Vaults

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]

Lobed Domes

Similar domes to that just described at Avignon are quite common in Spain, where for that matter the lantern itself had a very remarkable development. Thus in the cathedral of Zamora (consecrated 1144) there is a dome with sixteen ribs. It is not of perfectly simple type, however, for the masonry between the ribs is curved slightly outward, giving it the form of a lobed dome.[323] The lobes are comparatively small, but otherwise not unlike such larger ones as those in SS. Sergius and Bacchus at Constantinople (cir. 527) and the Serapeum of the Villa Adriana at Tivoli (125-135). As far as construction is concerned this arrangement made it possible to lay up the masonry between the ribs with little or no centering, so that once the ribs were in place, the task of completing the dome was a comparatively simple one. Unlike the “Gothic dome” which is later discussed, the thrusts were not materially decreased by the lobed plan and in its essentials the dome thus formed was precisely like the simple type. From the point of view of appearance these Spanish lanterns are certainly very beautiful. Usually pierced with windows in twelve out of the sixteen bays, and sometimes, as at Salamanca, with a few windows in the lower of the two stages forming the drum, they admit a great quantity of light to the very heart of the church where its presence is most needed. Moreover, the spherical pendentives from which the lanterns rise are more pleasing than the squinches generally found in France.

“Gothic Domes” or Double Chevets

Because of its resemblance to such ribbed domes as those just described it may be well to discuss here what may be called a “Gothic dome” if such a term be permissible. This is, in other words, the familiar chevet vault extended to cover a space of circular or octagonal plan. One of these vaults of circular plan and with eight ribs appears over the crossing of Saint Nicolas at Blois (Fig. 56). Unlike the ribbed dome, its masonry courses are not horizontal and concentric with the impost line, but practically at right angles to it, thus giving wall arches whose crowns are nearly as high as the central keystone itself. Each window cell is thus precisely like one-quarter of a four-part cross-ribbed vault. It was this form of double chevet vault which was frequently used as late as the Renaissance period in Italy, where it appears in such works as the Pazzi chapel at Florence (cir. 1420) (Fig. 57) and elsewhere though without

Fig. 56.—Blois, Saint Nicholas.