From the same front, from the end of the covered way, close to the dividing wall, a second bank of earth is given off, and, passing westwards to unite with the horn-work, divides the inner from the middle moat, and forms a part of the northern defences of the castle. Its inner face is partially lined by a wall, in which is a sluice-tunnel. This is the curved ridge.
II.—The Horn-work covering the western front of the castle, and placed between the middle and outer gates, is an irregular polygon of about three acres, revetted all round with a wall of 15 feet high, above which is a talus of about 8 feet more. From its south-western face issues one of the feeding springs of the lake. On the eastern, or longest face, is a semi-pier, to receive the drawbridge, of 20 feet span, from the opposite gatehouse of the middle ward. On the north-western face a similar semi-pier, between half-round bastions, seems to have supported the drawbridge, also of 20 feet span, giving access to the castle in this direction. Possibly each bridge was of two pieces, one dropping from each bank upon a central tressel or timber structure in the ditch.
III.—The Redoubt has already been mentioned as being formed by scraping down a knoll of gravel on the north-west quarter of the castle.
The body of this earthwork is quadrangular, capped at the three outer angles by three bastions, and excavated in the centre into a sort of casemate. The curtain, towards the castle, is intersected by two trenches, separated by a mound or cavalier, and leading into the centre of the work.
Outside the redoubt, and following the curve of its bastions, is a ditch, upon the outer three sides broad and deep, on the fourth side but slightly marked.
The ramparts of the redoubt are unprovided with either parapets for canon or banquettes for musquetry, and the scarp is continued unbroken to the rampart. Neither scarp nor counterscarp, though steep, has any retaining wall.
Beyond its main ditch is a spacious glacis, terminating in three low bastions and a shallow ditch. Both ditches were probably dry.
The whole work resembles much those thrown up in haste during the wars between Charles I. and the Parliament, and has either been partially destroyed, or, which seems more probable, has never been entirely completed. No doubt it was stockaded.
The inner and middle wards of the castle occupy the island, which has already been described as formed out of the end of the peninsula.
This island is scarped into a parallelogram, 111 yards east and west, by 96 north and south. The four angles are capped by large bastions, parts of circles. The intervening straight lines are termed, in fortification, curtains.