570 FIlE^X'H ARCHITECTURE. Part II. which flying buttresses were afterwards employed, partly as enabling the ai'chitect to obtain the required elevation without extraordinarily tall pillars or wide pier-spaces, both which were beyond the con- structive j)Owers of the earlier builders. These galleries were also useful as adding to the accommodation of the church, as people were able thence to see the ceremonies performed below, and to hear the mass and music as well as from the floor of the church. These advantages were counterbalanced by the greater dignity and archi- tectural beauty of the second arrangement (Woodcut No. 383), Avhere the whole heisrht was divided into that of the side-aisles and of a clere- story, separated from one another by a triforium gallery, which repre- sented, in fact, the depth of the wooden roof requisite to cover the side-aisles. When once this simple and beautiful arrangement was adopted, it continued with very little variation throughout the Middle Ages.^ 1 he proportions generally used were to make the aisles half the height of the nave. In other words, the string-course below the triforium divided the height into two equal parts; the space above that was divided into three, of which two were allotted to the clerestory, and one to the triforium.^ It is true there is perhaps no single instance in which the proportions here given are exactly preserved, but they sufficiently represent the general division of the parts, from which the architects only deviated slightly, sometimes on one side, sometimes on the other, according to their taste or caprice. The only really important change afterwards introduced was that of glazing the triforium gal- lery also, by adopting a flat roof, or one nearly so, over the side-aisles, as the nave in the church of St. Ouen at Rouen, or by covering each bay by a pyramidal roof not seen from the interior, as is shown in the Woodcuts Nos. 385 and 392. The whole walls of the church, with the slight exception of the spandrils of the great pier-arches, having thus become walls of glass, the mass of the vault being supported only by the deep and bold constructive lines of which the fi-aniowork of the glazed surfaces consists. In England we have not, as far as I am aware, any instance of a glazed triforium, but it is one of the most fascinating features in the later styles of the French architects, and where it retains its colored glass, which is indispensable, produces the most fairy-like effects. It is, however, questionable whether the deep shadow and constructive proi)riety of the English practice is not, on the whole, more satisfactory. In a structure of glass and iron nothing could be more appropriate than the French practice; but in a building of stone and wood more solidity is required to produce an effect Avhich shall be permanently jjleasing. 1 The earlier form is found retained at Noyon, at Paris, as shown in Wood- cut No. 360, and in most of the churches of the 12th century ; but in the first years of the l;}tli it gave place to the second, and was not afterwards revived. - See Introduction, page 29, Wood- cut No. 4.
