t general type. But it is
evident that the essential features of the arrangement are only two,
that is to say, one tier of massy work for foundation, suppose _c_,
missing the first two; and the receding tier or real foot of the wall,
_d_. The reader will find these members, though only of brick, in most
of the considerable and independent walls in the suburbs of London.

Sec. 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