may
be; but leave it we must, or we shall compose no more pictures to-day.

This law of radiation, then, enforcing unison of action in arising from,
or proceeding to, some given point, is perhaps, of all principles of
composition, the most influential in producing the beauty of groups of
form. Other laws make them forcible or interesting, but this generally
is chief in rendering them beautiful. In the arrangement of masses in
pictures, it is constantly obeyed by the great composers; but, like the
law of principality, with careful concealment of its imperativeness, the
point to which the lines of main curvature are directed being very
often far away out of the picture. Sometimes, however, a system of
curves will be employed definitely to exalt, by their concurrence, the
value of some leading object, and then the law becomes traceable enough.

218. In the instance before us, the principal object being, as we have
seen, the tower on the bridge, Turner has determined that his system of
curvature should have its origin in the top of this tower. The diagram
Fig. 34, p. 145, compared with Fig. 32, p. 137, will show how this is
done. One curve joins the two towers, and is continued by the back of
the figure sitting on the bank into the piece of bent timber. This is a
limiting curve of great importance, and Turner has drawn a considerable
part of it with the edge of the timber very carefully, and then led the
eye up to the sitting girl by some white spots and indications of a
ledge in the bank; then the passage to the tops of the towers cannot be
missed.

219. The next curve is begun and drawn carefully for half an inch of its
course by the rudder; it is then taken up by the basket and the heads of
the figures, and leads accurately to the tower angle. The gunwales of
both the boats begin the next two curves, which meet in the same point;
and all are centralized by the long reflection which continues the
vertical lines.

220. Subordinated to this first system of curves there is another, begun
by the small crossing bar of wood inserted in the angle behind the
rudder; continued by the bottom of the bank on which the figure sits,
interrupted forcibly beyond it,[64] but taken up again by the water-line
leading to the bridge foot, and passing on in delicate shadows under the
arches, not easily shown in so rude a diagram, towards the other
extremity of the bridge. This is a most important curve, indicating
that the force and sweep