Mediaeval Church Vaulting

by Clarence Ward

Ambulatories with Half Tunnel Vaults

Besides these annular vaults, there are a few examples of ambulatories with half tunnel vaults which may owe their origin to the desire of the builders to keep the outer impost of the vaults as low as possible and still raise the inner line above the apsidal arcade.[411] In any event such an ambulatory is occasionally found in churches where the aisles also are half-tunneled, as, for example, in the abbey church of Montmajour (cir. 1015-1018)[412] and in the twelfth century church of Saintes.[413] Though this type of vault apparently has no pre-Romanesque prototype, it is perhaps possible that the concentric aisle of the circular church of Rieux-Merinville (Aude) (eleventh century)[414] affords an earlier example of its use over a space of similar plan. There is also an interesting use of a half-tunnel vaulted triforium above the ambulatory and abutting the half dome of the apse which opens into it through five arches, in the church of Loctudy (Finistère) twelfth century.[415]

There are, however, circular buildings of the Byzantine and Carolingian periods with vaulted aisles which may well have furnished the prototypes for other methods of ambulatory vaulting which the Romanesque builders employed. One of these is the Royal Chapel at Aachen (796-804), in which the aisles are two stories high with the lower story covered by groined vaults of alternately square and rectangular plan with no transverse arches separating the bays.[416]