Based on the same simple arch, circle and cusp forms as the French tracery, the English geometric tracery is infinitely richer and more varied. The great east end and west windows of the cathedrals allowed the develop ment of four-, six- or eight-light windows, designed in two or three orders, carefully systematized, like the east window of Lincoln cathedral (c. 1280), in eight lights, with three orders. But the greatest change was in single order windows of smaller size. In these the use of cusps without circles became common, and all sorts of star-shaped, triangular and other geometric forms occur.
In the early years of the 14th century the English architects discovered that by the use of the ogee (q.v.) curve, or curve of double curvature, the occasional harsh angularities of the geometric style could be avoided, and wavy-lined tracery of great beauty produced. This gave rise to the so-called curvilinear tracery. Its simplest form is the reticu lated, or network window in which the entire upper part is filled with a regular all-over pattern of waving bars, rhythmically tan gent and then separating. But the introduction of the reverse curve set free the imagination of the designer, and an infinite number of varying types resulted, such as the rose window at Lincoln cathedral (135o), or the great west window at York (c. 1338).
By the end of the 3rd quarter of the i4th century a reaction had set in against this flowing curva ture, and the 15th century saw the new style—the so-called per pendicular—triumphant. It was based on one controlling idea— verticality. Mullions were run through unbroken from bottom to top. At intervals they were connected by horizontal bars running across the window, supported on little arches between the mul lions, thus dividing the whole window into tiers of little arch headed lights. At the top there is great variety of treatment, but almost always the upper lights are smaller than those below: and there was frequent use of curved bars intersecting the verti cals, and to some extent recalling the arched forms of the earlier styles. This new feeling appears in the transept window of Gloucester cathedral as early as 1335, and in a more developed form in the east window of the choir, which fills the entire east end, about 135o. During the 15th century the lines become more and more rectangular and the window heads have flatter and flatter arches. The climax of this development is reached in such enormous end windows as those of the King's College chapel, Cambridge, and St. George's chapel, Windsor (c. 1525).
Wall tracery of perpendicular character was widely used both for exterior and interior work during the 15th and early 16th centuries. Great areas are sometimes filled with tiers of traceried panels, as in the Henry VII. chapel, Westminster Abbey (begun 1502). In some cases, where flint was common, a tracery of cut stone, filled in with dark flints, decorates church exteriors, as in Long Melford church and St. Laurence at Ipswich. Traceried forms are also the basis of much screen, stall and tomb design of the 15th century; rood screens are particularly rich. Tracery is also the basis of the decorative rib treatments of fan vaulting. (See FAN VAULT; VAULT.) French Flamboyant Tracery.—In the last years of the i4th century the reverse curve came into use in French tracery, prob ably as the direct result of English curvilinear models. The French, however, soon gave tracery of this kind an individual spirit. In the best Flamboyant work, such as the tracery of S. Maclou, Rouen (begun 1432), and the west front of Rouen cathedral (begun 1481), all of the forms are slimmer and more flame-like than is usual in English work. Particularly interesting is the application of Flamboyant tracery to rose windows, lixe that of the south transept of Beauvais cathedral (1500-48 ), in which the radiating character of the earlier types is maintained, although combined with the reverse curve. Flamboyant tracery
forms the chief decoration of many gorgeous choir stalls and screens. The screen at Albi (c. 15oo) has tracery of unbelievable lace-like delicacy in its canopies, as well as larger patterns cover ing wall surfaces; the wood choir stalls of Amiens (1508-19) are even more delicate and the tracery is of the utmost richness and intricacy. Noteworthy, also, is the application of Flamboyant tracery forms to exterior detail, as in the porch of S. Maclou, Rouen, and the west front of S. Wulfran at Abbeville (148o).
Due to the Italian lack of understanding of Gothic structural principles, tracery never achieved in Italy the logical development of the north. The nearest approach to this is in the bands of tracery of Venetian palace windows, such as those of the Ca d'Oro (143o), by G. and B. Bon. Elsewhere, tracery was only understood as beautiful pattern, and much of it, even when copying the forms of bar tracery, is pierced from large sheets of marble, as in the triforium of the cathedral at Lucca (c. 1400) and the cloister of S. Maria della Verita, at Viterbo. Tracery in the Orient.—The Mohammedan designers not only followed Byzantine precedent in using pierced marble screens for windows but also, by the development of a new technique, invented a characteristic type of tracery, which combined the functions played by both leading and stone tracery in western work. This technique consisted in filling the window area with a pierced sheet of cement, each piercing being filled with a piece of coloured glass. Results of jewel-like intensity and brilliance were thus obtained, and being made of a plastic material, tracery of this type could have unlimited variety of pattern. The usual types found were basically floral, with the leaf shapes in glass, carefully arranged to give a sense of flow and growth. Such cement tracery is found particularly in the later work of Cairo, such as the mosque of Barkouk (c. 1384) and in the imperial Turkish work, such as the brilliantly jewelled windows in the 17th century mosque of Suleiman, Constantinople. In India, where ventilation is required, rather than floods of light, a differ ent type was developed, without glass, and in a richer material— carved and pierced marble. Thus, in almost all of the great Mogul palaces, and in many of the tombs, large, pointed arch openings are filled with sheets of white marble, pierced in the most elaborate patterns, of the finest scale. The most delicate example of this pierced, marble tracery is that of the screen around the sarcophagi in the Taj Mahal (q.v.), at Agra (1632-47).
Church architects of the loth century, work ing, frequently, in a modernized Gothic style, have found in tracery a congenial means of free expression. Both geometric and curvilinear forms have furnished inspiration, but patterns have been developed of a freshness and individuality frequently quite different from the mediaeval custom. In these, foliated ornament is frequently added to the tracery basis. Noteworthy examples occur in Liverpool cathedral (Sir G. G. Scott, architect, still, 1928, uncompleted) and in the west front of the church of the Heavenly Rest and the Beloved Disciple, New York (1928), by Mayers, Brust and Philip, the Goodhue associates. An entirely modern development is seen in the use of pre-cast cement tiles, pierced in geometric patterns and glazed, built up into large windows, as in the church of Notre Dame at Raincy, France (1924) by Perret Freres. (See GOTHIC ARCHITECTURE; INDIAN