The one in the north end is supposed to date from 1362. It is composed of six lights, and the head shows late geometrical tracery. The transom crossing the mullions is not visible from the outside. Below it a second set of mullions supports a small gallery which leads to the triforium. This window was repaired in 1512 and filled with glass of the period representing its chief figures--St. Augustine, St. Jerome, St. Gregory and St. Ambrose. Therefore it became known as =The Four Doctors of the Church=. Prior Castell, who had charge of the repairs, placed himself here kneeling before the Virgin. The opposite window, in the south end of the transept, is called the =Te Deum=. It contains six lights and is Perpendicular in style, dating between 1416 and 1446. There are corresponding stairways in the north-west and south-west corners of the transepts. Now we come to the =Tower=, supported on four large Norman piers with semicircular arches. We look above about seventy feet and see the first story of the lantern with a gallery. Panels, grotesque heads, corbels, crockets and finials and a string-course ornamented with the Tudor flower give us plenty to study. Then come the windows, each with two lights and divided by a transom, and, last of all, the handsome groined roof with bosses on the ribs. The =Choir= is the earliest part of the church. It contains Early Norman, Early English and Early Decorated work. The two later styles occur in the eastern part, and much beautiful detail is to be enjoyed. Where the one leaves off and the other begins affords interesting study. Carileph’s work is seen in the western bays. Arcades adorn the piers on both sides of the choir. The lower row has six arches and the upper three. All these are carved with foliage, heads and half figures. On each pier of the upper arcade there is an angel under a canopy. The vaulting dates from the Thirteenth Century. It is quadripartite. Square leaves and the dog-tooth decorate the ribs. The bosses at the points of intersection are very fine. An altar-tomb with the effigy of =Bishop Hatfield= (1345-1381), beneath the Bishop’s Throne, reminds us of the days when bishops were princes and warriors. Hatfield led eighty archers to the siege of Calais; and during his rule at Durham the battle of Neville’s Cross occurred (see page 236). Such a magnificent bishop had to have a magnificent tomb; and so, according to the custom of the day, he designed one for himself. Here he lies beneath a canopy that once was bright with painting and gilding. His effigy shows his splendid robes. The =Screen=, separating the choir from the nave, dates from 1870-1876. The =Choir-stalls= were made from 1660 to 1672 to replace the originals destroyed by the Scottish prisoners incarcerated in the Cathedral in 1650 after the battle of Dunbar.