the length and breadth of England, especially in the southern counties.
Our review of Norman architecture will not be complete without a brief notice of the castles with which every eminence of any importance was crowned in the time of William the Conqueror and his successors. The keep, or main tower, was the part first built; in some instances it stood alone; in not a few, thanks to its great solidity, it still stands, though all subsequent additions have disappeared. One of these castles, when fully completed by the additions of subsequent generations, was often of vast extent, and usually of irregular form, as the shape of the ground indicated. The exterior line of defence (or outer bailey) was surrounded by a deep ditch called a fosse or moat, protected by an outwork called a barbican, consisting of a strong wall, with turrets, for the defence of the great gate and drawbridge. The external wall enclosing this outer bailey was placed within the ditch, and was 8 to 10 ft. thick by 20 to 30 ft. high, with a parapet (i. e. a wall breast-high) and embrasures (i. e. openings in a wall or parapet). Square towers were raised here and there above the walls, and contained lodgings for the officers engaged in the defence of the castle, etc. The tops of the turrets and of the wall were flat, and the defenders of the castle stood on them to hurl down missiles upon their assailants. The great gate was flanked by a tower on each side, with rooms over the entrance, which was closed with a massive folding door of oak, and provided with a portcullis (i. e. a falling gate, consisting of a strong grating of timber, with pointed spikes, for striking in the ground on which it was thrown, made to slide up and down in a groove of stone- work, inside the entrance arch). Within
