§ X. It is evident, however, that the general type, Fig. II., will be subject to many different modifications in different circumstances. Sometimes the ledges of the tiers _a_ and _b_ may be of greater width; and when the building is in a secure place, and of finished masonry, these may be sloped off also like the main foot _d_. In Venetian buildings these lower ledges are exposed to the sea, and therefore left rough hewn; but in fine work and in important positions the lower ledges may be bevelled and decorated like the upper, or another added above _d_; and all these parts may be in different proportions, according to the disposition of the building above them. But we have nothing to do with any of these variations at present, they being all more or less dependent upon decorative considerations, except only one of very great importance, that is to say, the widening of the lower ledge into a stone seat, which may be often done in buildings of great size with most beautiful effect: it looks kind and hospitable, and preserves the work above from violence. In St. Mark's at Venice, which is a small and low church, and needing no great foundation for the wall veils of it, we find only the three members, _b_, _c_, and _d_. Of these the first rises about a foot above the pavement of St. Mark's Place, and forms an elevated dais in some of the recesses of the porches, chequered red and white; _c_ forms a seat which follows the line of the walls, while its basic character is marked by its also carrying certain shafts with which we have here no concern; _d_ is of white marble; and all are enriched and decorated in the simplest and most perfect manner possible, as we shall see in Chap. XXV. And thus much may serve to fix the type of wall bases, a type oftener followed in real practice than any other we shall hereafter be enabled to determine: for wall bases of necessity must be solidly built, and the architect is therefore driven into the adoption of the right form; or if he deviate from it, it is generally in meeting some necessity of peculiar circumstances, as in obtaining cellars and underground room, or in preparing for some grand features or particular parts of the wall, or in some mistaken idea of decoration,--into which errors we had better not pursue him until we understand something more of the rest of the building: let us therefore proceed to consider the wall veil. FOOTNOTES: [33] Many walls are slightly sloped or curved towards their tops, and have buttresses added to them (that of the Queen's Bench Prison is a curious instance of the vertical buttress and inclined wall); but in all such instances the slope of the wall is properly to be considered a condition of incorporated buttress. CHAPTER V. THE WALL VEIL.