It is pierced north and south by a portal 6 feet 9 inches broad, which commences by a square cell, vaulted, with a cross and longitudinal rib, chamfered, and pierced at the intersection by an octagonal cavity. Two door jambs then reduce the opening by a foot, and between them, in the vault, is a hole 9 inches diameter, apparently intended for a chain which passed out over the rib of the further door, and worked, still within the tower, a light bridge, the recess for which is seen outside the door. The chamber here widens by 3 feet, to allow space for those defending the east wall. When this bridge was down, a way was opened to a door in the west wall, outside which is a platform, whence a second bridge dropped southwards across the ditch. The upper story of this postern tower was one large chamber for working the inner bridge. A door leads from it upon the rampart walk of the east curtain. Above this were the battlements of the postern, two stages below that of the contiguous tower. In the Tudor reigns these buildings were encumbered with additions in brick, timber, and plaster, which still remain, and much obscure the original details. This postern tower is Perpendicular, perhaps the work of Richard II. Besides the bulwarks and towers just described, the inner ward was strengthened against surprise by several cross walls and gates, breaking it up into independent sections. One of these gates crossed from Bell to Byward Tower, and another, it is said, crossed north of Beauchamp Tower. There were walls with gates across the ward, on either side of Traitors’ Gate, so that prisoners could be brought in by water and led across into the Bloody Tower gate, without any chance of rescue in the outer ward, and indeed without being seen. Another gateway of a stronger description, and with towers, extended from Lanthorn to near Cradle Tower; and another also, already mentioned, opened in the small curtain between Salt and Well Tower. There was at least one more gateway in the short curtain east from Salt Tower. The ward, between all these gates, must have been intended to be open; but, at least since the Tudor reigns, it has been encumbered with private houses. Here the operations of the Mint were carried on with much inconvenience; and the north and west limbs of the ward still bear the name of Mint Street, and the east limb, of Irish Mint Street. The curtain or scarp wall of this ward was, no doubt, the work of Henry III., and much of the wall is still original. In the west wall, near Byward, below a modern battery of two guns, are six loops, probably old, but lighting modern casemates, and beneath each an air-hole. Also, on the north front, close west of the new bastion in the wall, is a pointed arched door, long closed up, but probably an original water-gate. West of this also is an original loop, no doubt marking the place of a mural chamber not now accessible. [Illustration: MIDDLE TOWER.]