aisles had to be left free, outer aisles, similarly divided, were made. Great French cathedrals, like Amiens, not only have a complicated series of chapels opening from the aisles of the apse, but have their naves lined with chapels, which were formed by removing the outer walls of the aisles to a level with the outer face of the buttresses. The ordinary parish church had no need of these elaborate arrangements, although in towns and in districts where money was plentiful and its possessors recognised its true source, plans hardly less spacious than those of the cathedral and monastery churches came into being. But it is obvious that, in a church where there were no more than two or three altars, space would be gained by removing them from the body of the church to the end of the aisles. In some twelfth century churches there were probably altars against the wall on either side of the narrow chancel arch; and, in later days, as at Ranworth and Patricio, when the rood screen filled the lower part of a broad arch, altars were placed against the screen. In the first case, the chancel arch might have been widened; in the second case, the sides of the screen would have been freed, by the addition of aisles into which the altars could have been removed. Sec. 42. The most common plan of the aisled church is formed by an aisled nave with a long aisleless chancel, western tower, and south porch. So common is this that it may be spoken of as the normal plan of the larger English parish church. There must have been, we already have said, a very large number of aisleless churches in England at the time of the Conquest. Where Norman builders reconstructed parish churches, they showed a distinct preference for the aisleless plan. But, in many churches, built about or soon after the beginning of the twelfth century, aisles were planned and executed. The walls of earlier churches were entirely taken down, and new arcades built in their place, not necessarily on the precise line of the old foundations. Aisled twelfth century naves on a magnificent scale may be seen, for example, at Melbourne in Derbyshire, and Sherburn-in-Elmet, between York and Leeds. Both places were important episcopal residences: Melbourne belonged to the bishops of Carlisle; the manor of Sherburn was the head of a barony of the archbishops of York, who, all through the middle ages, did much to promote architecture on their domains. Another twelfth century nave of great magnificence is that of Norham-on-Tweed, which belonged to the cathedral priory of Durham; and, although we must not assume that it was built at the expense of the monastery, it doubtless owes its stately proportions to the influence of the mother house. Less imposing in elevation, but richer in refined detail, are such aisled naves as those of Long Sutton in south Lincolnshire, and Walsoken in west Norfolk, which belong to the later part of the twelfth century. The plans in each