by flat buttresses which do not reach below the bottoms of the aisle windows. The eleven windows in the clerestory above are all alike, divided only by flat buttresses. Aisle and clerestory both show a plain parapet and corbels. The bold buttresses on the north side, with their panelled and crocketted pinnacles, save it from the monotony of the south side, which, however, was once greatly concealed by cloisters and convent buildings, and is even now far more enclosed than the northern side. The low #Central Tower#, the coping of which is only 35 feet above the ridge of the transept roof, is Norman, though, as explained before, of later date than the transepts. It is of a simple square form, 150 feet high by 50 wide, and is divided by a string course into two storeys, the lower of which is plain with small round-headed windows; the larger upper storey has on each side three narrow round-headed windows, which form a kind of arcade round the upper part of the tower, surmounted by a zig-zag string course. At the angles are engaged shafts. The massive manner in which the tower was rebuilt in the eleventh century can be better appreciated from within, when we come to the piers which support it. The building has been said to prove that the Normans of the period were "still bad masons and imperfectly acquainted with the principles of construction," the masses of masonry employed showing an enormous waste of both labour and materials. But the architects at any rate gained their end, since the tower has stood to the present day. The strength of the original Norman work, indeed, is so great that for all the 250 feet of nave no flying-buttresses were required to support the later vaulting.