power, even had he been so
inclined, to obtain shafts high enough to sustain the whole external
gallery, as it is sustained in the nave, on one arcade. He had, as above
noticed, a supply of shafts of every sort and size, from which he chose
the largest for his nave shafts; the smallest were set aside for
windows, jambs, balustrades, supports of pulpits, niches, and such other
services, every conceivable size occurring in different portions of the
building; and the middle-sized shafts were sorted into two classes, of
which on the average one was about two-thirds the length of the other,
and out of these the two stories of the facade and sides of the church
are composed, the smaller shafts of course uppermost, and more numerous
than the lower, according to the ordinary laws of superimposition
adopted by all the Romanesque builders, and observed also in a kind of
architecture quite as beautiful as any we are likely to invent, that of
forest trees.

Nothing is more singular than the way in which this kind of
superimposition (the only right one in the case of shafts) will shock a
professed architect. He has been accustomed to see, in the Renaissance
designs, shaft put on the top of shaft, three or four times over, and he
thinks this quite right; but the moment he is shown a properly
subdivided superimposition, in which the upper shafts diminish in size
and multiply in number, so that the lower pillars would balance them
safely even without cement, he exclaims that it is "against law," as if
he had never seen a tree in his life.

Not that the idea of the Byzantine superimposition was taken from trees,
any more than that of Gothic arches. Both are simple compliances with
laws of nature, and, therefore, approximations to the forms of nature.

There is, however, one very essential difference between tree structure
and the shaft structure in question; namely, that the marble branches,
having no vital connexion with the stem, must be provided with a firm
tablet or second foundation whereon to stand. This intermediate plinth
or tablet runs along the whole facade at one level, is about eighteen
inches thick, and left with little decoration as being meant for hard
service. The small porticos, already spoken of as the most graceful
pieces of composition with which I am acquainted, are sustained on
detached clusters of four or five columns, forming the continuation of
those of the upper series, and each of these clusters is balanced