both, in a
specific manner, and including a great group of arts which neither, of
necessity, _tint_, nor for the sake of form merely, _shape_, the
substances they deal with; but construct or arrange them with a view to
the resistance of some external force. We construct, for instance, a
table with a flat top, and some support of prop, or leg, proportioned in
strength to such weights as the table is intended to carry. We construct
a ship out of planks, or plates of iron, with reference to certain
forces of impact to be sustained, and of inertia to be overcome; or we
construct a wall or roof with distinct reference to forces of pressure
and oscillation, to be sustained or guarded against; and therefore, in
every case, with especial consideration of the strength of our
materials, and the nature of that strength, elastic, tenacious, brittle,
and the like.

Now although this group of arts nearly always involves the putting of
two or more separate pieces together, we must not define it by that
accident. The blade of an oar is not less formed with reference to
external force than if it were made of many pieces; and the frame of a
boat, whether hollowed out of a tree-trunk, or constructed of planks
nailed together, is essentially the same piece of art; to be judged by
its buoyancy and capacity of progression. Still, from the most wonderful
piece of all architecture, the human skeleton, to this simple one,[107]
the ploughshare, on which it depends for its subsistence, _the putting
of two or more pieces together_ is curiously necessary to the
perfectness of every fine instrument; and the peculiar mechanical work
of Daedalus,--inlaying,--becomes all the more delightful to us in
external aspect, because, as in the jawbone of a Saurian, or the wood of
a bow, it is essential to the finest capacities of tension and
resistance.

5. And observe how unbroken the ascent from this, the simplest
architecture, to the loftiest. The placing of the timbers in a ship's
stem, and the laying of the stones in a bridge buttress, are similar in
art to the construction of the ploughshare, differing in no essential
point, either in that they deal with other materials, or because, of the
three things produced, one has to divide earth by advancing through it,
another to divide water by advancing through it, and the third to divide
water which advances against it. And again, the buttress of a bridge
differs only from that of a cathedral in having less w