but will always, if they can, have one bank to
sun themselves upon, and another to get cool under; one shingly shore to
play over, where they may be shallow, and foolish, and childlike, and
another steep shore, under which they can pause, and purify themselves,
and get their strength of waves fully together for due occasion. Rivers
in this way are just like wise men, who keep one side of their life for
play, and another for work; and can be brilliant, and chattering, and
transparent, when they are at ease, and yet take deep counsel on the
other side when they set themselves to their main purpose. And rivers
are just in this divided, also, like wicked and good men: the good
rivers have serviceable deep places all along their banks, that ships
can sail in; but the wicked rivers go scooping irregularly under their
banks until they get full of strangling eddies, which no boat can row
over without being twisted against the rocks; and pools like wells,
which no one can get out of but the water-kelpie that lives at the
bottom; but, wicked or good, the rivers all agree in having two kinds of
sides. Now the natural way in which a village stone-mason therefore
throws a bridge over a strong stream is, of course, to build a great
door to let the cat through, and little doors to let the kittens
through; a great arch for the great current, to give it room in flood
time, and little arches for the little currents along the shallow shore.
This, even without any prudential respect for the floods of the great
current, he would do in simple economy of work and stone; for the
smaller your arches are, the less material you want on their flanks. Two
arches over the same span of river, supposing the butments are at the
same depth, are cheaper than one, and that by a great deal; so that,
where the current is shallow, the village mason makes his arches many
and low: as the water gets deeper, and it becomes troublesome to build
his piers up from the bottom, he throws his arches wider; at last he
comes to the deep stream, and, as he cannot build at the bottom of that,
he throws his largest arch over it with a leap, and with another little
one or so gains the opposite shore. Of course as arches are wider they
must be higher, or they will not stand; so the roadway must rise as the
arches widen. And thus we have the general type of bridge, with its
highest and widest arch towards one side, and a train of minor arches
running over the flat shore on the