124 Mcdiceval MiHtary Architecture in England. raneous with the substitution of a covering" of lead for one of shingles or ^tone tiles. Usually the flat exterior faces are relieved by broad pilaster strips of slight projection from 5 feet to 10 feet wide, by 6 inches in depth, one at the end of and flanking each face, and in the larger keeps one, or even two, between them. The flanking pilasters are commonly placed so as to cover the angle, the two meeting ; sometimes, however, they do not quite meet, and the solid angle is replaced by a hollow nook, occasionally, in late keeps, as at Castle Rising and Scar- borough, occupied by a bold bead or engaged shaft. In all but the very small keeps these flanking pilasters are continued 8 feet to 10 feet clear above the parapet as the outer faces of square turrets, now usually ruined. At Hedingham one, partly perfect, remains. Those on the White Tower and at Rochester are in part original, and certainly represent, very closely, original structures. At Bowes there seems to have been but one turret, covering the stairhead. The intermediate pilasters usually stop either just below the base of the parapet or below an upper window. At Dover they are carried into the parapet and support slight internal recesses there, but this is very rare. The pilasters usually are divided by strings into stages, marking the levels of the different floors, and all rise from a common plinth, sometimes slight, but sometimes, as at Mailing, Kenilworth, Guildford, Scarborough, and Norham, where one side rises from lower ground, the plinth is on that side 8 feet to 10 feet high, and has at Kenilworth and Norham a very bold base. The set-off and string-course are sometimes carried along both wall and pilasters. At Colchester and at the White Tower a projecting half-round forms the apse of the chapel, and the pilasters appear upon it ; at Rochester a rounded corner is solid, save at one story, but this is probably due to a reconstruction. The pilasters are one of the most marked features of the Norman style, and their presence at once distinguishes a keep of that period from the fine fourteenth-century towers, as Borthwick and Lochleven, found in Scotland, as well as from towers of Early English date, where the pilasters are bolder and narrower, and often, as at Exeter Castle, chamfered at the angles. The keep wall is from 7 feet to 14 feet thick, and at the base of the foundation sometimes 2ofeet. That of Colchester is reputed to be 30 feet. That of the Tower of London is said to have taken six weeks to pierce, with all modern tools and appliances. The lower 14 feet of the keep of Newcastle is thought to be solid. The wall usually diminishes in thickness as it rises, sometimes by external sets-ofl" of 6 inches, more commonly by an internal
