169

On the shape of derived shadows.

ALL BODIES, IN PROPORTION AS THEY ARE NEARER TO, OR FARTHER FROM THE SOURCE OF LIGHT, WILL PRODUCE LONGER OR SHORTER DERIVED SHADOWS.

Among bodies of equal size, that one which is illuminated by the largest light will have the shortest shadow. Experiment confirms this proposition. Thus the body m n is surrounded by a larger amount of light than the body p q, as is shown above. Let us say that v c a b d x is the sky, the source of light, and that s t is a window by which the luminous rays enter, and so m n and p q are bodies in light and shade as exposed to this light; m n will have a small derived shadow, because its original shadow will be small; and the derivative light will be large, again, because the original light c d will be large and p q will have more derived shadow because its original shadow will be larger, and its derived light will be smaller than that of the body m n because that portion of the hemisphere a b which illuminates it is smaller than the hemisphere c d which illuminates the body m n.

[Footnote: The diagram, given on Pl. IV, No. 2, stands in the original between lines 2 and 7, while the text of lines 3 to 6 is written on its left side. In the reproduction of this diagram the letter v at the outer right-hand end has been omitted.]

Taken from The Notebooks of Leonardo da Vinci edited by Jean Paul Richter, 1880.

II * IV
Notebooks of Leonoardo da Vinci
III: Six books on Light and Shade.
. . .
149
light.
150,
151,
152
On the proportion of light and shade.
153,
154,
155,
156,
157
Definition of derived shadow.
158,
159
Different sorts of derived shadows.
160,
161,
162
On the relation of derived and primary shadow.
163,
164,
165
On the shape of derived shadows.
166,
167,
168,
169,
170,
171,
172,
173,
174
On the relative intensity of derived shadows.
175,
176,
177,
178,
179
Shadow as produced by two lights of different size.
180,
181
The effect of light at different distances.
182
Further complications in the derived shadows.
183,
184,
185,
186,
187
On the shape of the cast shadows.
188,
189
. . .