The most normal form of a window in an arched style is simply an opening straight through the wall covered by a barrel arch. This is, however, obviously defective in its fitness for diffusing light in the interior, a deficiency which, though slight in the case of a large window in a thin wall, becomes serious when the window is narrow and the wall thick. The simplest method of meeting this is to splay the jambs and arch of the window, at, for example, an angle of forty-five degrees, so as to allow for the spreading of the rays of light within. In English architecture of pre-Norman days, this was most frequently done, both within and without, by placing the glass a long way from the outer face, or perhaps in the mid-thickness of the wall (Fig. 154). This had the advantage of splaying the head or arch as well as the jamb, which allowed more high light to enter; an advantage often increased by splaying the exterior of the arch _more_ than the jambs, giving it a bonnet-like shape, and so obtaining still higher light (Fig. 155). Windows thus splayed inside and out, may be seen in the Castle Church at Dover--some few of these are not arched but had oak lintels, splaying upwards at about forty-five degrees (Fig. 156). The bonnet-headed window may be seen at Holy Trinity Church, Colchester; Clapham Church, Bedfordshire and many other buildings. [Illustration: Fig. 154.] [Illustration: Fig. 155.] [Illustration: Fig. 156.] [Illustration: Fig. 157.--St. Pantaleon’s Church, Cologne.] The deeply splayed window may also be seen in part of St. Pantaleon’s Church at Cologne (Fig. 157), which is a work of the tenth century, and in the aisles of the Basse-œuvre at Beauvais, a church of at least as early a date, so that it may be viewed as a feature common during these early periods of Romanesque which preceded that from which our Mediæval styles were developed. During the rise of the Norman style, a different system was more usually adopted, the splay of the jambs and arch being mainly internal. A series of humble village churches at the back of Dover Cliffs have windows in which the glass was flush with the exterior, and all the splay put inside; many both in Normandy and in this country differ from this only in having a very small external splay, and even when the exterior is shafted the inner splay often comes close to the face of the recessed order. [Illustration: Fig. 158.--Chancel, Burgh Church, Norfolk.] This excessive flushness is less frequent as the style advances, and in Early English, though sometimes, as in the beautiful chancel at Burgh in Norfolk, (Fig. 158) the glass is sometimes brought extremely close to the outside: it is usual to have at least a few inches of splay around it. In transitional work, as in Norman, the internal splay, often of very great width, usually runs round the arch concentrically; but in developed Early English, [Illustration: Fig. 159.] [Illustration: Fig. 160.] [Illustration: Fig. 161.]