_Carlisle._--The defences of Carlisle are said to date from Roman times. The present castle is well situated on the highest point of ground within the city, about 60 feet above the river. Its walls enclose a roughly triangular space of an extent of about three acres. The keep, rectangular in plan, measures 66 feet by 60 feet and is at present 68 feet in height. It rose to a greater height originally. As one would infer from the dimensions of the keep, it is of Norman workmanship, but it has received a good many strengthening additions in comparatively recent times. The keep is situated in the inner ward which occupies the eastern end of the castle enclosure. It is approached by means of two gatehouses, one near the middle of the southern wall, leading into the outer ward, and the other about the middle of the wall which separates the outer and inner ward. The south wall of the castle is of Norman date: the other walls are of both Norman and Edwardian construction. The castle (doubtless as a fortress comprising mostly earthworks and palisading), is attributed to William II. The work was doubtless continued (probably in masonry), by Henry I, and completed in 1135 by David, King of Scotland, who also heightened the city walls. Carlisle was, perhaps, only in a very minor sense of any importance as one of the coast defences of England. Its castle, its walls, and other defences were doubtless intended, primarily, to keep the Scottish border raiders in check, and to serve as a military base against Scotland. The general principle of defending the coast by means of strong castles erected near the shore was in due course extended in accordance with local requirements. Thus, Tynemouth Priory, situated on the coast of Northumberland, was provided as we have seen, with a gatehouse closely resembling in form and massive strength the gatehouse of a mediaeval castle. It is certain that its builders contemplated and provided for military defence. Houses of great personages, and of wealthy institutions such as monastic houses were also built on a defensive or semi-defensive scale. PART IV COAST DEFENCES UNDER HENRY VIII AND LATER ON THE EAST COASTS OF KENT AND SUSSEX OF THE ESTUARIES OF THE THAMES, MEDWAY, ETC. OF THE SOUTH COAST DEFENCES ON THE EAST COASTS OF KENT AND SUSSEX During the reign of Henry VIII an interesting group of castles, or more properly blockhouses, intended entirely for coast defence, was erected on the coasts of Kent and Sussex. The particular circumstances which gave occasion for these defensive works at this period are quaintly set forth by William Lambard in his "Perambulation of Kent."[23]