Page:A book of folk-lore (1913).djvu/179

176 mediæval churches, castles, and mansions where there is a parapet rising from the wall and obscuring a portion of the roof, this parapet is supported at intervals by corbels, that usually represent heads of either men or beasts, very frequently grotesque. These corbels are not of any great structural importance, though they add to architectural decoration. They are, in fact, a perpetuation of a traditional usage earlier than the construction of buildings of stone. When buildings such as halls were erected of wood, and even later, when the walls were of masonry, the tye beams of the roof projected beyond the supporting walls. These tye beams sustained the principals and the king-post, and rested on the wall-plate. Such was the earliest and simplest form of roof, and it is one that remained in use till Norman times. The stability of the roof depended on the tye beam, which, where it protruded beyond the walls, was sawn off against the grain, and was there most vulnerable, subject to the drive of the weather, and liable to rot. For