hafts in the angles (_a_, _h_) are both of deep
purple marble; the two next pairs, _b_ and _g_, are of white marble; the
pairs _c_ and _f_ are of purple, and _d_ and _e_ are of white: thus
alternating with each other on each side; two white meeting in the
centre. Now observe, _the purple capitals are all left plain; the white
are all sculptured_. For the old builders knew that by carving the
purple capitals they would have injured them in two ways: first, they
would have mixed a certain quantity of grey shadow with the surface hue,
and so adulterated the purity of the color; secondly, they would have
drawn away the thoughts from the color, and prevented the mind from
fixing upon it or enjoying it, by the degree of attention which the
sculpture would have required. So they left their purple capitals full
broad masses of color; and sculptured the white ones, which would
otherwise have been devoid of interest.

Sec. XVIII. But the feature which is most to be noted in this apse is a
band of ornament, which runs round it like a silver girdle, composed of
sharp wedges of marble, preciously inlaid, and set like jewels into the
brickwork; above it there is another band of triangular recesses in the
bricks, of nearly similar shape, and it seems equally strange that all
the marbles should have fallen from it, or that it should have been
originally destitute of them. The reader may choose his hypothesis; but
there is quite enough left to interest us in the lower band, which is
fortunately left in its original state, as is sufficiently proved by the
curious niceties in the arrangement of its colors, which are assuredly
to be attributed to the care of the first builder. A word or two, in the
first place, respecting the means of color at his disposal.

Sec. XIX. I stated that the building was, for the most part, composed of
yellow brick. This yellow is very nearly pure, much more positive and
somewhat darker than that of our English light brick, and the material
of the brick is very good and hard, looking, in places, almost
vitrified, and so compact as to resemble stone. Together with this brick
occurs another of a deep full red, and more porous substance, which is
used for decoration chiefly, while all the parts requiring strength are
composed of the yellow brick. Both these materials are _cast into any
shape and size_ the builder required, either into curved pieces for the
arches, or flat tiles for filling the triangles; and, what