of the window. Again, you can still better
confirm this proof by placing two sticks, as shown at g h ; and you
will see the line drawn from the centre of the shadow directed to
the centre m and prolonged to the horizon n f .
[Footnote: B here stands for cerchio del' orizonte tramontano on
the original diagram (the circle of the horizon towards the North); A for levante (East) and C for ponete (West).]
139.
Every shadow with all its variations, which becomes larger as its
distance from the object is greater, has its external lines
intersecting in the middle, between the light and the object. This
proposition is very evident and is confirmed by experience. For, if a b is a window without any object interposed, the luminous
atmosphere to the right hand at a is seen to the left at d . And
the atmosphere at the left illuminates on the right at c , and the
lines intersect at the point m .
[Footnote: A here stands for levante (East), B for ponente
(West).]
140.
Every body in light and shade is situated between 2 pyramids one
dark and the other luminous, one is visible the other is not. But
this only happens when the light enters by a window. Supposing a b to be the window and r the body in light and shade, the light to
the right hand z will pass the object to the left and go on to p ; the light to the left at k will pass to the right of the
object at i and go on to m and the two lines will intersect at c and form a pyramid. Then again a b falls on the shaded body
at i g and forms a pyramid f i g . f will be dark because
the light a b can never fall there; i g c will be
illuminated because the light falls upon it.
Light and shadow with regard to the position of the eye (141—145).
141.
Every shaded body that is larger than the pupil and that interposes
between the luminous body and the eye will be seen dark.
When the eye is placed between the luminous body and the objects
illuminated by it, these objects will be seen without any shadow.
[Footnote: The diagram which in the original stands above line 1 is
given on Plate II, No 2. Then, after a blank space of about eight
lines, the diagram Plate II No 3 is placed in the original. There is
no explanation of it beyond the one line written under it.]
142.
Why the 2 lights one on each side of a body having two pyramidal
sides of an obtuse apex leave it devoid of shadow.
[Footnote: The sketch illustrating this is on Plate XLI No 1.]
143.
A body in shadow situated between the light and the eye can never
display its illuminated portion unless the eye can see the whole of
the primary light.
[Footnote: A stands for corpo (body), B for lume (light).]
144.
The eye which looks (at a spot) half way between the shadow and the
light which surrounds the body in shadow will see that the deepest
shadows on that body will meet the eye at equal angles, that is at
the same angle as that of sight.
[Footnote: In both these diagrams A stands for lume (light) B for ombra (shadow).]
145.
OF THE DIFFERENT LIGHT AND SHADE IN VARIOUS ASPECTS AND OF OBJECTS
PLACED IN THEM.
If the sun is in the East and you look towards the West you will see
every thing in full light and totally without shadow because you see
them from the same side as the sun: and if you look towards the
South or North you will see all objects in light and shade, because
you see both the side towards the sun and the side away from it; and
if you look towards the coming of the sun all objects will show you
their shaded side, because on that side the sun cannot fall upon
them.
The law of the incidence of light.
146.
The edges of a window which are illuminated by 2 lights of equal
degrees of brightness will not reflect light of equal brightness
into the chamber within.
If b is a candle and a c our hemisphere both will illuminate the
edges of the window m n , but light b will only illuminate f
g and the hemisphere a will light all of d e .
147.
OF PAINTING.
That part of a body which receives the luminous rays at equal
confirm this proof by placing two sticks, as shown at g h ; and you
will see the line drawn from the centre of the shadow directed to
the centre m and prolonged to the horizon n f .
[Footnote: B here stands for cerchio del' orizonte tramontano on
the original diagram (the circle of the horizon towards the North); A for levante (East) and C for ponete (West).]
139.
Every shadow with all its variations, which becomes larger as its
distance from the object is greater, has its external lines
intersecting in the middle, between the light and the object. This
proposition is very evident and is confirmed by experience. For, if a b is a window without any object interposed, the luminous
atmosphere to the right hand at a is seen to the left at d . And
the atmosphere at the left illuminates on the right at c , and the
lines intersect at the point m .
[Footnote: A here stands for levante (East), B for ponente
(West).]
140.
Every body in light and shade is situated between 2 pyramids one
dark and the other luminous, one is visible the other is not. But
this only happens when the light enters by a window. Supposing a b to be the window and r the body in light and shade, the light to
the right hand z will pass the object to the left and go on to p ; the light to the left at k will pass to the right of the
object at i and go on to m and the two lines will intersect at c and form a pyramid. Then again a b falls on the shaded body
at i g and forms a pyramid f i g . f will be dark because
the light a b can never fall there; i g c will be
illuminated because the light falls upon it.
Light and shadow with regard to the position of the eye (141—145).
141.
Every shaded body that is larger than the pupil and that interposes
between the luminous body and the eye will be seen dark.
When the eye is placed between the luminous body and the objects
illuminated by it, these objects will be seen without any shadow.
[Footnote: The diagram which in the original stands above line 1 is
given on Plate II, No 2. Then, after a blank space of about eight
lines, the diagram Plate II No 3 is placed in the original. There is
no explanation of it beyond the one line written under it.]
142.
Why the 2 lights one on each side of a body having two pyramidal
sides of an obtuse apex leave it devoid of shadow.
[Footnote: The sketch illustrating this is on Plate XLI No 1.]
143.
A body in shadow situated between the light and the eye can never
display its illuminated portion unless the eye can see the whole of
the primary light.
[Footnote: A stands for corpo (body), B for lume (light).]
144.
The eye which looks (at a spot) half way between the shadow and the
light which surrounds the body in shadow will see that the deepest
shadows on that body will meet the eye at equal angles, that is at
the same angle as that of sight.
[Footnote: In both these diagrams A stands for lume (light) B for ombra (shadow).]
145.
OF THE DIFFERENT LIGHT AND SHADE IN VARIOUS ASPECTS AND OF OBJECTS
PLACED IN THEM.
If the sun is in the East and you look towards the West you will see
every thing in full light and totally without shadow because you see
them from the same side as the sun: and if you look towards the
South or North you will see all objects in light and shade, because
you see both the side towards the sun and the side away from it; and
if you look towards the coming of the sun all objects will show you
their shaded side, because on that side the sun cannot fall upon
them.
The law of the incidence of light.
146.
The edges of a window which are illuminated by 2 lights of equal
degrees of brightness will not reflect light of equal brightness
into the chamber within.
If b is a candle and a c our hemisphere both will illuminate the
edges of the window m n , but light b will only illuminate f
g and the hemisphere a will light all of d e .
147.
OF PAINTING.
That part of a body which receives the luminous rays at equal
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