ints where the
angle of incidence can equal the angle of reflection, as it would seem
to do, because the surface being rough presents facets at different
angles, from some of which it can be reflected to the eye right up to
point 3. The number of these facets that can so reflect is naturally
greatest near the high lights, and gets gradually less as the surface
turns more away; until the point is reached where the shadows begin, at
which point the surface positively turns away from the light and the
reflection of direct light ceases altogether. After point 3 there would
be no light coming to the eye from the object, were it not that it
receives reflected light. Now, the greatest amount of reflected light
will come from the direction opposite to that of the direct light, as
all objects in this direction are strongly lit. The surface of the wall
between points E and H, being directly opposite the light, will give
most reflection. And between points 5 and 6 this light will be reflected
by the cone to the eye in its greatest intensity, since at these points
the angles of incidence equal the angles of reflection. The other parts
of the shadow will receive a certain amount of reflected light,
lessening in amount on either side of these points. We have now rays of
light coming to the eye from the cone between the extreme points 7 and
8. From 7 to 3 we have the light, including the half tones. Between 1
and 2 the high light. Between 3 and 8 the shadows, with the greatest
amount of reflected light between 5 and 6.

[Illustration: Plate XIX.

ILLUSTRATING CURVED LINKS SUGGESTING FULLNESS AND FORESHORTENING]

I should not have troubled the reader with this tedious diagram were it
not that certain facts about light and shade can be learned from it. The
first is that the high lights come much more within the edge of the
object than you would have expected. With the light directly opposite
point 7, one might have thought the highest light would have come there,
and that is where many students put it, until the loss of roundness in
the appearance of their work makes them look more carefully for its
position. So remember always to look out for high lights within the
contours of forms, not on the edges.

The next thing to notice is that #the darkest part of the shadow will
come nearest the lights between points 3 and 5#. This is the part turned
most away from the direction of the greatest amount of reflected light,
and therefore rece