series of large apsidal recesses or chapels along each side. This type is again followed at Orvieto cathedral.
The most perfect plan for a great church would seem to be that in which the central eastern apse is surrounded by an ambulatory from which small circular-ended chapels open out – one, three, four, five or seven. This is the plan which was adopted in the main line of progress into Gothic, and it continued to be used right through the Middle Ages. This fine scheme probably dates from Carolingian days, and three important churches, at Tours, Dijon and Le Mans, were built in this form at the end of the tenth century. Churches of the same type were built in England, first for the abbey of St Augustine, Canterbury, and the cathedrals of Winchester and Gloucester, during the last quarter of the eleventh century. An apse was an essential member of a great church during the Romanesque period. In its centre the bishop had his throne lifted high above the altar as ruler of the assembly; this broken remnants at Norwich still shew. The planning of a great church implied the dealing with several common factors which might be variously combined. The nave might be one, or three, or five spans wide; there might be a transept of one, two, or three spans, and the eastern limb might have a simple apse, or parallel apses, or an ambulatory and a series of radiating chapels. The position of towers was another factor to be considered. Their positions were partly, doubtless, a matter of choice, but largely they were conditioned by structural requirements. A great single tower at the west end, as at Ely, will stop the thrusts of the inner arcading as well as the more usual pair of towers. In French churches towers were frequently put at the transepts also, and Winchester cathedral seems to have been intended to have transeptal towers. In Germany towers are often seen on either side of the apse. At Tournai four towers built around the crossing against the transepts support the central lantern, making a most impressive group of five spire-capped towers. At Exeter two massive towers stand over small square transepts. A third great controlling factor in the design of churches was that of vaulting. The possibilities of rearing vaults were explored in all sorts of ways. All three spans might have barrel vaults, or those over the aisles might be quadrants rising higher against the nave than where they fell on the aisle walls. The bays might be vaulted transversely, a favourite device in Burgundy, or they might be covered by a combination of longitudinal and transverse vaults interpenetrating and forming "groined" vaults. This last became the standard form for the vaults of churches in north-western Europe, and the tradition was carried forward into Gothic. The use of this scheme allowed of high windows in every bay, and concentrated the thrusts at intervals above the piers of the inner arcades. One school of French Romanesque experimented with a series of domes covering square compartments, and the curious church at Loches has its nave covered by stone pyramidal erections like low pitched spires. It
