down to the ground floor, which contained the stores, and another stair leads to the upper floors and battlements. The upper floor is generally appropriated as the owner's private apartment or bedroom. Many of the older keeps have been raised a story in Norman times to obtain additional accommodation, and a flat leaden roof introduced, which was useful for working military engines. This was managed without heightening the building, by utilising the space formerly occupied by the gabled roof.
The French keeps are similar in general idea, but varied in details. In some of them there is a large open top story, where all the garrison might assemble for the defence of the parapets. The Norman keeps have always walls of great thickness, and trust to the passive resistance they thus offer to attack. The idea of defending the
Fig. 1.—Keep of Château d'Arques from the North-East.
keep by flanking towers has not yet been recognised. The ground floor is sometimes vaulted, and the upper floors are invariably of wood. There are usually only small loops or air-holes on the ground floor, and the windows in the upper floors are small externally, although with wide bays internally, generally containing stone seats. In large halls there is sometimes an upper passage in the thickness of the wall, with a row of windows in the outside wall, and arches in the inner wall next the hall, like the triforium arcade of a church. The interior stairs are spiral, and
