The next drawing shows a plan of the third or uppermost floor, at the level of the clerestory of the chapel. Here the outer wall is shown perforated all round by a mural gallery, which communicates with the three well staircases and with the chapel. Finally follows a vertical section of the whole keep from east to west, in which is shown the chapel with its clerestory above and its two tiers of crypts below. These drawings, which more especially belong to the detailed description of the Tower of London which follows in its place, are here inserted as illustrating what is written of Norman rectangular keeps in general. [Illustration] The kitchen, though a necessary appendage to a keep, is not often to be discovered. Probably the cooking was of a simple character, mostly carried on before an open fire, or by boiling, or broiling over a brazier. There is a kitchen in the forebuilding at Rochester, high up; and one at the first-floor level in a mural chamber, at Castle Rising and at Norwich. The kitchen when it was in a distinct chamber was at the level of the hall, or even above it. The defences of the outer doorway in a Norman keep were usually one or two stout doors of oak, strengthened with iron, and held close by one or two bars, also of oak, which ran back into deep holes in the wall about four inches square. The herse or portcullis, though used in other parts of castles, was rare in the keep. It is a very old method of defence, formed of stone in the Great Pyramid, and the groove for which remains in the city gate of Pompeii. When employed, as in the keeps of Scarborough, Hedingham, and Rochester, it was a single grate, probably of oak spiked and plated with iron, and it was worked from a mural chamber over the archway. Sometimes, from the narrow dimensions of the groove, the grate seems to have been wholly of iron. It was worked by chains or cords wrapped round a cylinder or windlass, such as is still in use in the main gate-house of the Tower. Norman keeps very seldom retain their original parapets or turrets. The parapet was about two feet thick and five feet high. It was either plain or had broad merlons and narrow embrasures. Usually it was a mere continuation of the wall, without corbels or any contrivance to widen the rampart walls, which were of sufficient thickness for the walk. At Rochester, holes are seen at the base of the parapet for beams to carry a _brétasche_ or external gallery, but these probably are not original. The angle turrets are usually mere places of arms, the rampart walks passing through them. Sometimes they have an upper floor reached by a stone stair or a movable ladder.