Mediaeval Church Vaulting

by Clarence Ward

Apses with Ribbed Half Domes

The first series lies largely in southern France in the Romanesque school of Provence. Here there are a certain number of churches, among them the chapel of Saint Honorat in Les Alyscamps at Arles (Bouches-du-Rhône) (eleventh century?), in which the surface of the half dome is broken out at regular intervals into a number of flat, pilaster-like, radiating strips, forming a part of the actual masonry of the vault. These divide the half dome in much the same manner as true Gothic ribs, but they do not support it in any way and seem to have been used for the decoration which such a change in the surface of the vault produced.[341] As a general rule, these ribs radiate from a point slightly back from the crown of the apse arch and often from a raised masonry ring as in the chapel just cited. They vary, however, both in number, thickness and width, some being comparatively thick and widening out from the central keystone as in the cathedral of Notre Dame-des-Doms at Avignon (Vaucluse), others being but slightly salient and of the same width throughout like those in Saint Honorat at Arles.

Much larger in number and extent is the second series of churches with rib-vaulted apses, though they are in general of later date than those in Provence. Their radiants have a certain structural character, for they are independent of the vault surface and were doubtless erected in most cases as a permanent centering to aid in the construction of the half dome. They do not, however, aid to any extent in its support, for the courses of masonry in the vaults are still horizontal and concentric with the curve of the apse, and the completed half domes would therefore stand just as well were the ribs removed. It may be that they were introduced in order to make the apse correspond more closely in appearance with the ribbed vault which had in many cases been introduced in the naves of the churches in which the ribbed half domes are found. In any event, they mark a stage in apse vaulting between the simple half dome and the developed chevet, which is worthy of careful consideration. Most of these vaults date from the second quarter of the twelfth century and are to be found within the zone of influence of the Ile-de-France, though occasionally an example is found at a long distance from this center as in the case of Sant’ Abondio at Como,[342] Santa Maria di Castello at Corneto-Tarquinia in Italy,[343] and such churches as that of the Monasterio de la Oliva (Navarra) in Spain,[344] (1198). The number of ribs varies considerably, though two is most common particularly in the smaller churches and chapels.[345] Of these, the church at Morienval (Oise) [(Fig. 77)] furnishes a good, though recently reconstructed, example, while Saint Georges-de-Boscherville [(Fig. 61)] may be cited as possessing a large apse of similar character.

The important thing in a comparison of these two vaults is the difference in the lighting of the completed apse. At Boscherville, it was a simple matter to pierce the exterior wall with windows, in this case in two stages, and still keep their crowns practically below the level of the impost of the half dome, since the latter rested directly upon the outer walls. But at Morienval there was an ambulatory, and in order to get a clerestory above its arches, the windows had to be cut into the curved surface of the half dome itself, with the result that they were so deep as to prove of only limited usefulness. Other examples could be cited where this same attempt is made to obtain sufficiently large windows by shoving their heads into the half dome,[346] while at Beaulieu (Corrèze)[347] the windows lie entirely above the impost.

Besides the ribbed half dome just described, there is still another type to be seen in the Lady chapel of the church of Saint Martin-des-Champs at Paris [(Fig. 65)]. Its plan is a trefoil and the vault is made up of a series of segments of domes with salient ribs marking their intersections. As far as construction is concerned, there is really no change from that of the more common half dome, for the courses of masonry are still horizontal and the ribs merely serve as centering and as a means of subdividing the surface to be vaulted and clearly marking the lines of intersection. The vault would stand equally well were the ribs removed and is, in structural character, very similar to the celled domes of the Villa Adriana at Tivoli and of S.S. Sergius and Bacchus at Constantinople.

Fig. 61.—Saint Martin-de-Boscherville, Saint Georges.

“Groined Half Domes”

Another form of apse vault of which there would seem to be a number of examples prior to the introduction of ribbed vaulting may perhaps be termed the “groined half dome.” It is a vault resembling a segmental dome except that the segments do not run down to a common impost, but form a series of window cells not unlike those of a groined vault but not running all the way to the vault crown. The earliest of these vaults appears to be that in the crypt of Saint Laurent at Grenoble (Isère) (sixth century).[348] Rivoira has shown[349] that Roman prototypes of this form can be found in the so-called “Temple di Siepe” (second century) at Rome, the vestibule of the Villa Adriana at Tivoli (125-135) and elsewhere. There are also a number of Romanesque examples. Of these, one is in the chapel off the south transept of Saint Nicholas at Caen (1080-1093),[350] while another is to be found in Saint Andrew’s chapel at Canterbury cathedral (cir. 1110).[351] These vaults closely resemble the true Gothic chevet which was soon to follow them, and they might seem to be its prototypes were it not for the fact that their construction is of an entirely different character. All are built of small stone or rubble and were undoubtedly laid up on a wooden centering with no particular regard for the direction in which the masonry courses ran, or possibly with these courses like those in a half dome. The construction was thus a combination of half dome and groined vaulting and not at all of the ribbed type. That they may, however, have been of influence in the development of the true chevet will be later suggested.