Page:Charles Moore--Development and Character of Gothic Architecture.djvu/171

Rh the very slight pier buttress—which rises through the roof to the intrados of the abutting arch—is hardly noticed in a general view of the structure (Fig. 82). A comparison of this clerestory with the nearly contemporaneous clerestory of the nave of Amiens (Fig. 44) affords an instructive illustration of the difference between Anglo-Norman and Gothic construction in this portion of an edifice. The Cathedral of Salisbury is commonly considered as exhibiting the early English style in its purest form, and it is therefore an important building for comparison with the new architecture of the Continent. The structure was begun in 1220, contemporaneously with the nave of Amiens, and the two buildings may be taken as fairly typical of the respective styles. The nave of Salisbury is roofed with quadripartite vaults of greater simplicity than those of the nave of Lincoln. Its rib system contains none but functionally necessary ribs, and in this system, as well as in the forms of the vault surfaces, there are many points of likeness to French vaulting. The most important of these is that which results from the forms of the longitudinal arches, which rise for some distance in a line more nearly vertical than is common in England, and give something of those twisted surfaces that characterise more truly Gothic structures. Fig. 83, a perspective view of one of the vaulting conoids, will illustrate this. In this vaulting the longitudinal arch is provided with a more pronounced rib than is usual in buildings of this class. An important structural defect will