The exterior of the keep has suffered so much that hardly any detail is left, nearly all the facing stone having disappeared. The most perfect side is that towards the gorge, difficult of access (Fig. 10). From it, however, we learn that the building consisted of a plain mass of ashlar work broken at the angles and the middle of each side by a shallow projecting pier. Each corner of the building has a small circular shaft with cap and base of the ordinary Norman type. The window openings must have been narrow, as was usually the case, and probably of very simple detail, matching that of the doorway and the shoot of the _garde-robe_. At the parapet level there were probably four turrets rising from the angle buttresses, but all traces of them have gone. Indeed all that can be gathered of the external appearance is that it was of the usual severe type and that the detail was of the simplest. While castles and their keeps were still in full occupation, but towards the later years of their existence, there were built a number of fortified manor houses of stone. It is quite probable that these buildings embodied in permanent materials a type of plan that had long prevailed in a less durable form. The keep was contrived so as to be as economical of space as possible; the rooms were piled one on the top of the other. But where defensive precautions were not so imperative, and space was not so valuable, the rooms were placed alongside of each other on the ground. The manor house, therefore, followed a type of plan somewhat different from that of the keep, but in both cases the hall was the principal apartment; it was the sleeping, eating, and living room of the household. As years went by the keep type of plan fell into disuse; its singular lack of comfort may easily account for this. The manor house type, on the contrary, survived, and it is this type which has been developed, through century after century, into the house of modern times. It is, however, curious to find a few late survivals of the keep, some of them built long after the necessity for castles had disappeared; others, owing to their geographical position, being the natural expression of the wants of the district. Among the former is Tattershall Castle in Lincolnshire, built by Lord Treasurer Cromwell in the fifteenth century, the same who built the great manor house of South Wingfield in Derbyshire. Both of these houses will be more fully mentioned in their chronological order. Among the latter are many of the peel-towers of Northumberland, which continued to be built with the ancient restricted arrangements until the accession of James I. Cocklaw Tower, near Hexham, is a fairly late example (Figs. 11, 12); it was built in the sixteenth century and contained hardly more accommodation than the Peak Castle. At the ground level was a cellar entered from the outside by a doorway protected by machicolations. Above the cellar was the hall, entered by an external door several