566 FRENCH ARCHITECTURE. Part II. 418. Window at Kheiins. to form a discharging arch. When once this was done it required only a glance from an experienced builder to see that if the dis- charging arch were strong enough, the whole of the wall between the buttresses might be removed without endangering the safety of the building. Tliis was accordingly soon done. The pier between the two lancets be- came attenuated into a mullion, the circle lost its independence, and was grouped with them under the discharging arch, which was carried down each side in boldly splayed jambs, and the whole became in fact a traceried window. In the cathedral at Chartres we have ex- amples of the two extremes of these ti'ansi- tional windoAvs. In the windows of the aisles of the nave (Woodcut No. 416) the circle is small and insignificant, and only serves to join together the two lancets. In the clerestory (Woodcut No. 417), which is somewhat later, the circle is all important and quite over- powers the lower part. Here it is, in fact, a circular window, supported by a rectilinear substructure. In both these instances the dis- charging arch still retains its circular form, and the tracery is still imperfect, inasmuch as all the openings are only holes of various forms cut into a flat surface, whereas to make it per- fect, it is necessary that the lines of two con- tiguous openings should blend together, being se])arated by a straight or curved moulded mullion, and not merely pierced as they are in this instance. This may, perhaps, be better illustrated by one of the windows of the side- aisles at Rheims, where the pointed Gothic window has become complete in all its essential parts. Even here, it will be observed how awkwardly the circle fits into the spherical triangle of the upper part of the window. Indeed, there is an insuperable awkwardness in the small triangles necessarily left in fitting circles into the spaces above the lancets, and beneath the pointed head of the openings. When four or five lights were used instead of two, this defect became more apparent ; and even in the example from St. Ouen (Woodcut No. 419), one of the most beautiful in France, the architect has not been able to obviate the discordance between the conflicting lines of the circle and spherical triangle. At 419. Window at St. Ouen.
