240
CLIV. The Sun in Front of the Picture 241
CLV. The Shadow of an Inclined Plane 244
CLVI. Shadow on a Roof or Inclined Plane 245
CLVII. To Find the Shadow of a Projection or Balcony
on a Wall 246
CLVIII. Shadow on a Retreating Wall, Sun in Front 247
CLIX. Shadow of an Arch, Sun in Front 249
CLX. Shadow in a Niche or Recess 250
CLXI. Shadow in an Arched Doorway 251
CLXII. Shadows Produced by Artificial Light 252
CLXIII. Some Observations on Real Light and Shade 253
CLXIV. Reflection 257
CLXV. Angles of Reflection 259
CLXVI. Reflections of Objects at Different Distances 260
CLXVII. Reflection in a Looking-glass 262
CLXVIII. The Mirror at an Angle 264
CLXIX. The Upright Mirror at an Angle of 45 deg to
the Wall 266
CLXX. Mental Perspective 269

BOOK FIRST

THE NECESSITY OF THE STUDY OF PERSPECTIVE
TO PAINTERS, SCULPTORS, AND ARCHITECTS

Leonardo da Vinci tells us in his celebrated _Treatise on Painting_ that
the young artist should first of all learn perspective, that is to say,
he should first of all learn that he has to depict on a flat surface
objects which are in relief or distant one from the other; for this is
the simple art of painting. Objects appear smaller at a distance than
near to us, so by drawing them thus we give depth to our canvas. The
outline of a ball is a mere flat circle, but with proper shading we make
it appear round, and this is the perspective of light and shade.

'The next thing to be considered is the effect of the atmosphere and
light. If two figures are in the same coloured dress, and are standing
one behind the other, then they should be of slightly different tone,
so as to separate them. And in like manner, according to the distance of
the mountains in a landscape and the greater or less density of the air,
so do we depict space between them, not only making them smaller in
outline, but less distinct.'[1]

[Footnote 1: Leonardo da Vinci's _Treatise on Painting_.]

Sir Edwin Landseer used to say that in