]

Fig. 264 shows this in profile. Here the sun is on the same plane as the
picture, and the shadow is cast sideways.

Fig. 265 shows the same thing, but the sun being behind the object,
casts its shadow forwards. Although the lines of light are parallel,
they are subject to the laws of perspective, and are therefore drawn
from their respective vanishing points.

[Illustration: Fig. 265.]

CXLIX

SHADOWS CAST BY THE SUN

Owing to the great distance of the sun, we have to consider the rays of
light proceeding from it as parallel, and therefore subject to the same
laws as other parallel lines in perspective, as already noted. And for
the same reason we have to place the foot of the luminary on the
horizon. It is important to remember this, as these two things make the
difference between shadows cast by the sun and those cast by artificial
light.

The sun has three principal positions in relation to the picture. In the
first case it is supposed to be in the same plane either to the right or
to the left, and in that case the shadows will be parallel with the base
of the picture. In the second position it is on the other side of it,
or facing the spectator, when the shadows of objects will be thrown
forwards or towards him. In the third, the sun is in front of the
picture, and behind the spectator, so that the shadows are thrown in the
opposite direction, or towards the horizon, the objects themselves being
in full light.

CL

THE SUN IN THE SAME PLANE AS THE PICTURE

Besides being in the same plane, the sun in this figure is at an angle
of 45 deg to the horizon, consequently the shadows will be the same
length as the figures that cast them are high. Note that the shadow of
step No. 1 is cast upon step No. 2, and that of No. 2 on No. 3, the top
of each of these becoming a plane of shade.

[Illustration: Fig. 266.]

[Illustration: Fig. 267.]

[Illustration: Fig. 268.]

When the shadow of an object such as _A_, Fig. 268, which would fall
upon the plane, is interrupted by another object _B_, then the outline
of the shadow is still drawn on the plane, but being interrupted by the
surface _B_ at _C_, the shadow runs up that plane till it meets the rays
1, 2, which define the shadow on plane _B_. This is an important point,
but is quite explained by the figure.

Although we have said that the rays pass over the top of the object
casting the shadow, in the case of an archway or similar f