Brick was a building material in the time of the Romans and its use was most probably never wholly discontinued. In Tudor times many of the buildings were of brick and timber, and picturesque brick and timber structures of various dates will be found in all parts of our county. The gallery at Christ's Hospital, Abingdon, shown on the next page, is a good example. All the clay formations in Berkshire have been used for brick and tile making. The works at Katesgrove and other places on the banks of the Kennet at Reading are very old and certainly go back to the sixteenth century. In 1901 there were 1029 men and 35 women engaged in brick, cement, pottery, and like works in Berkshire. The limestone rocks of the Corallian formation have been much quarried in the district between Faringdon and the river Thames near Oxford, and the stone has been used in buildings of all ages. Chalk has also been extensively quarried for building purposes. There is a great deal of chalk in the walls of the Dean's Cloisters and also in other parts of Windsor Castle. Chalk frame-work may be seen in many church windows, at Old Windsor and Bray for instance. At Waltham St Lawrence there is a very curious example, for some flints are actually left in the chalk mullions of the east window of the north chantry. It may be of interest to mention that in the valley of the Seine in northern France chalk has been extensively used as a building stone--in some of the best buildings at Rouen for example. Flints from the chalk are much used as building-material in Berkshire; they are employed fixed in concrete to form the core of walls, as at Reading Abbey, and as facing to walls with stone corners and window-frames. Shottesbrooke Church is faced with beautifully dressed little flints. In other churches the flints are not squared but in the rough state. At St Mary's Church, Reading, there is building of a chess-board pattern, one set of squares being stone and the others formed of small dressed flints. Another example of this chequer-work is shown in the view of the church at White Waltham here given. The hard sandstone which has been derived from the Eocene strata and is termed "sarsen" (see p. 40) is an important Berkshire building stone. There is a great deal of it in the walls all over Windsor Castle, several of the towers and walls being faced with sarsen. In some of the Berkshire gravel beds there is a hard irony conglomerate, and this has been used as a building material. There is a good deal in the tower of St Giles Church, Reading, and in the parish church at Wokingham. There are many building-materials used in the county which have been brought from other districts, but this chapter only deals with things found in Berkshire itself.