The curtain of the outer ward is in three parts: one, 330 feet long, and curved, encloses the ward on the west or landward side, and connects the gatehouses with the mural towers. This wall is 6 feet thick, and 20 feet high, and is defended by the main fosse. Besides openings from the gatehouses, there is a direct access to this rampart from the court by a mural staircase built against the wall. The rampart walk is protected by a parapet and a rere wall, both of which, to give breadth to the walk, are thrown out upon corbels or false machicolations.
The second part of the curtain is straight, or nearly so, and extends 50 feet in length along the river cliff, from the great gatehouse to the south-east drum tower. Its rampart is accessible from each end. This wall is 30 feet high and 7 feet thick.
The third portion of the curtain also runs along the river cliff, and extends 90 feet from the north-east drum tower to the north gatehouse, near which it makes a salient angle. Between this angle and the gate it is 5 feet thick; elsewhere, only 2 feet. Possibly there was a tower at the angle.
The mural towers are three in number, all placed in the western curtain. They are half round, 30 feet high, 22 feet in diameter, with an external projection of 8 feet, and a slight square projection within formed by the gorge wall. They have a ground floor, looped, a first floor with a fireplace, and a chamber on the level of the rampart walk and forming a part of it. The walls are 5 feet thick. The middle tower of the three has fallen into the fosse. The masonry of these towers is rude, and they are ill-bonded into the wall.
The offices in this ward are represented by the walls of a detached building, 65 feet by 30 feet, with high gables, placed west of the inner ward; another room, 60 feet by 35 feet, built against the river curtain, near the northern gatehouse; and some outbuildings, kitchens probably, and a bakehouse, built against the curved curtain, close west of the same gatehouse. These buildings were probably intended for the accommodation of the garrison.
The main ditch sweeps round the north, west, and south sides of the outer ward, opening upon the river cliff at, and rising towards each end. The opening at the south-east end, near the great gatehouse, is closed by a batardeau, which seems to have been embattled towards the river, and to have been approached from the barbican. There are some traces of a similar wall at the other end, next the north gatehouse. This ditch is high above the river, but is fed by land waters, and part of it is still wet. It is about 30 feet broad, and of considerable depth. Westward it gives off a branch which divides the north and south outworks, and communicates with the ditches of the former.
The barbican appears, from the traces of its foundations, to have been a small, circular tower. It occupied a rocky knoll on the counterscarp of the main ditch, opposite the great gateway, and on the edge of the steep bank of the river. It evidently was intended to cover the drawbridge, and to force those who arrived by this entrance to pass exposed to the fire of the adjacent western curtain. This work seems to have been cut off from the other outworks by a dry ditch, or covered way, leading from the river, south-west of the barbican towards the main ditch.
The outworks are divided into north and south platforms by the branch of the main ditch already mentioned.
The south platform is defended on the east by the mill leat. It was walled in, and seems to have been about 170 yards long by 130 yards broad. Part of the wall remains on the west side and on the north, along the edge of the branch ditch. At the south end, the approach still lies through the outer gatehouse, part only of which is destroyed. The portal, a drop arch with portcullis grooves, remains; above it are three windows with flat, segmental arches. From the sill of the central window a hole opens upon the outside of the portal, probably for the passage of missiles. The building has a ground and upper floor. There are no traces of ditch or drawbridge. The work is rubble. There does not appear to have been any ashlar. The style is Perpendicular—possibly of the date of the great gatehouse, probably later. Grose gives a drawing of this gatehouse in 1786, in which it appears much in its present condition.
The northern platform covers the north and west quarters of the castle. It measures about 130 yards long by 90 yards broad, and is enclosed within a wet ditch, a branch of which nearly cuts off its northern portion, leaving a narrow neck towards the river, across which lay the approach to the south entrance. Within the ditches of this work are high banks, and indications of a slight wall, and perhaps of a tower, near the entrance passage.