THE BEAUCHAMP TOWER, TOWER OF LONDON.
Ravensburgh Castle, Hexton, Herts.—The northern escarpment of the Chiltern Hills is marked by numerous deep ravines leading down with winding courses to the lowlands. This has the effect of leaving bold bluffs of chalk standing up between them, and upon one of these this remarkably fine hill fortress is placed. In addition to the two ravines lying at the sides it is still further isolated by a third running at right angles between the others. The castle occupies 16 acres of the western half of this plateau, and possesses double ramparts on three sides and triple on the north. The section AB shows the steep descent into the ravine upon the south side, and DE indicates the same, while clearly showing the three lines of defence formed by the two ditches. The scarps are remarkable for their clean and smooth surfaces, the chalk presenting the appearance of having been cut with a huge knife. The entrances into the defence lie at nearly 500 feet above the sea-level.
RAVENSBURGH CASTLE, HEXTON, HERTS.
One of the most prominent examples of the class is Mam Tor, a great hill rising to a height of 1700 feet above sea-level, and dominating Castleton and Edale, Derbyshire. Upon the summit of this eminence is a remarkable earthwork enclosing about 16 acres of land, round which the original rampart must have been nearly three-quarters of a mile in length. Natural defences of a very marked character are upon two sides of the triangular enclosure, consisting of steep slopes which descend for a considerable distance. Upon the summit of these slopes two formidable ramparts with an accompanying fosse have been constructed, thus adding still further to an almost unassailable position. The agricultural inhabitants of the district often term it "The Shivering Mountain" from the many little avalanches of shale which are dislodged from its sides. Upon the northern part the natural defences are not so apparent, as the ridge of an adjoining hill approaches at that point. An entrance to the Fort occurs there at the present time, as shown in the plan, but not in its primitive condition. The only method of entering was by means of the narrow passage shown at the S.W., defended by a fortified mound at its inner mouth, which in turn was defended by a larger mound lying to the N.W. A small spring of water still rises within the enclosure and escapes through the N.W. break. The interior has not been levelled, and a central spine of rock traverses it from north to south. Undoubtedly Mam Tor furnishes us with one of the finest examples of a fortified hilltop to be found in England.