The portal opens from the bridge by a low drop arch, 12 feet broad and 12 feet high, reduced by two deep chamfers to 10 feet opening, followed by a broad jamb, in which are loop openings from the lodges. This is succeeded by a 6-inch portcullis groove, with a chase of 16 inches in the vault, to allow of the passage of a heavy wooden grate. Then follows a heavy rib, pierced with three round holes, which slightly converge, and are probably for the beams of a stockade, supposing the gates to be forced; and behind is a rebate with hinges for the valves of a door, opening inwards. The middle portion of the portal, which begins here, has a flat timber roof, 18 feet high. In it is a second portcullis groove, and the doors of the warders’ lodges. Finally is the inner archway, without jambs, but with a bold triple rib forming the arch. The south lodge door enters a lobby, 8 feet by 4 feet, vaulted in chalk, with a southern loop raking the postern. A pointed door on the left or east face opens into a garderobe, with a loop to the east, now closed. Opposite, a short passage, also vaulted, and with a cross rib, leads into the south or warders’ lodge. This is an octagon, 15 feet 9 inches from face to face. In each angle is a slender octagonal pier, engaged on a face and two half-faces, with a sort of bell-cap and stilted base, both octagonal. From each pier spring a main rib and two half-ribs. The former meet in the centre in a plain joint; the latter form lancet arches at the gable of each cell. All are narrow and plainly chamfered. Of the eight vaulting cells the ridge lines are horizontal, and have no ribs. The ribs and piers are of freestone, the vaults of chalk. From the floor to the pier caps is 6 feet 11 inches. The total height is 17 feet. [Illustration: BYWARD TOWER AND POSTERN.] In each of the faces is a recess. That on the north-east is the entrance. The south-east is occupied by a fireplace, no doubt representing an original one; The other six are looped. The north lodge is entered through a lobby, 7 feet 9 inches square, and 15 feet high, vaulted in four cells, with four slender chamfered hip-ribs, springing from octangular corbels, one at each angle. There is no boss. Each cell has a profile half-rib in its gable. In the east side is a long two-light window beneath a segmental recess, which seems original. This window, and the proportions and general elegance of this chamber, point to its possible use as an oratory. Those who entered the Tower might well need to be met by spiritual support on the threshold.