Each bay of the #Nave# is divided into two sub-bays. The main bays have massive piers with engaged shafts on the recessed faces. The bases of these are cruciform in plan, though the arms of the cross are very short. At the height of the springing of the arch the shafts are surmounted by plain cushion capitals. The division into sub-bays is effected by the introduction midway of a massive round column on a square base. These columns are ornamented in various ways, by channels cut on the face. Some take the form of a zig-zag, some a spiral, others a spiral in two directions, forming a trellis-like pattern, and others again are reeded vertically. Their capitals are octagonal cushions. The arches of the sub-bays are recessed square, with the usual Norman roll moulding, decorated with chevrons, and on the wall face a square billet. The chevron ornament is absent in the earlier work in the choir and transepts. The triforium is almost uniform throughout the whole church. In each sub-bay it consists of two small arches under one larger one, with the tympanum solid. Here also the capitals are cushions and perfectly plain. [Illustration: Triforium and Clerestory.] Above the triforium is the clerestory, which contains one light to each sub-bay, and surmounting all is the vaulting, which springs from the piers and from grotesquely carved corbels between the triforium arches. The vaulting ribs are ornamented with chevrons on either side of a bold semi-circular moulding. So much for the general arrangement of the bays. Some idea of the massiveness of the structures may be gathered when it is known that each group of the clustered pillars separating the bays covers an area of two hundred and twenty-five square feet at its base, while those of the cylindrical columns of the sub-bays are twelve feet square, and the columns themselves have a circumference of over twenty-three feet. There is little room to doubt that the effect obtained by the old builders of Durham was intentional. The masterly way in which great masses of solid masonry, greater than was constructively necessary, are handled, and the reticence and delicacy of the ornament combine to prove this. There is in the whole scheme a delightful union of great power and vigour in the masses, and of tenderness and loving care in the detail.