The inner-ward wall probably surrounded the mound, on the outside of its ditch, and was thus open to attack when the outer ward was taken. The old tower, last taken, and the fall of a part of which reduced the garrison to surrender, was probably the donjon or shell crowning the mound. This would be of Norman date, and therefore might well be called the old tower, as distinguished from Falk’s additions, and the repairs after the siege by Stephen. Thus, if the explanation be accepted, Bedford Castle had a shell keep or donjon upon a mound, surrounded by a ditch and wall, and this again by another wall, at a greater distance, the principal storehouses and dwelling being, as was usual, in this larger or outer ward. The History of Bedford Castle and of its siege are the subject of an elaborate paper by the late Rev. C. H. Hartshorn, privately printed in 1861. BERKHAMPSTEAD CASTLE, HERTS. The Castle of Berkhampstead stands in the parish of Berkhampstead St. Peter, in the county of Hertford, and, geologically, upon the lower chalk. Its position is in a chalky bottom, on the left bank of the Bulborne rivulet. Between the stream and the castle the ground is naturally low and marshy, but it is now traversed by the Grand Junction Canal and the London and North-Western Railway, which, with the water-course and the turnpike-road, separate the castle from the town. To the east and north-east of the castle the ground rises steeply towards Whitehill and Berkhampstead Common. To the west and north-west it rises more gradually towards Berkhampstead-place. Between the two, towards the north, is a combe or nearly dry valley, occupied by the old park, called the Berkhampstead estate, and in this valley stands the castle, about 400 yards from its termination in the river. The constituent parts of the castle are a mound; an inner _enceinte_ or ward; an inner ditch; a second _enceinte_; a second ditch; a third _enceinte_, enveloping the northern half only; a ravelin upon the west face; and a third or exterior ditch, also confined to the northern half of the work. The mound is wholly artificial. It is conical, about 60 feet high and 40 feet diameter at the top, having steep sides and a wet ditch round three-fourths of its circumference. Its top was crowned with a circular shell of wall, about 8 feet thick, of which the foundations only remain. Up its southern side is a curtain-wall, much ruined, and about 8 feet thick. This commences at the ground level at the top of the mound, and runs into a fragment of the _enceinte_ wall of the inner ward. It evidently connected this wall with the keep, and was probably, as at Tamworth, parapeted on either face of its rampart walk. It was not continued down the further side of the mound, which was not a part of the _enceinte_, but a citadel placed outside it, and connected with it only by a single wall.