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Authors: Leonardo Da Vinci
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HUMOUR OF THE EYE.
An experiment, showing how objects transmit their images or
pictures, intersecting within the eye in the crystalline humour, is
seen when by some small round hole penetrate the images of
illuminated objects into a very dark chamber. Then, receive these
images on a white paper placed within this dark room and rather near
to the hole and you will see all the objects on the paper in their
proper forms and colours, but much smaller; and they will be upside
down by reason of that very intersection. These images being
transmitted from a place illuminated by the sun will seem actually
painted on this paper which must be extremely thin and looked at
from behind. And let the little perforation be made in a very thin
plate of iron. Let a b e d e be the object illuminated by the sun
and o r the front of the dark chamber in which is the said hole at n m . Let s t be the sheet of paper intercepting the rays of the
images of these objects upside down, because the rays being
straight, a on the right hand becomes k on the left, and e on
the left becomes f on the right; and the same takes place inside
the pupil.
[Footnote: This chapter is already known through a translation into
French by VENTURI. Compare his ' Essai sur les ouvrages
physico-math�matiques de L. da Vinci avec des fragments tir�s de ses
Manuscrits, apport�s de l'Italie. Lu a la premiere classe de
l'Institut national des Sciences et Arts.' Paris, An V (1797).]
The practice of perspective (72. 73).
72.
In the practice of perspective the same rules apply to light and to
the eye.
73.
The object which is opposite to the pupil of the eye is seen by that
pupil and that which is opposite to the eye is seen by the pupil.
Refraction of the rays falling upon the eye (74. 75)
74.
The lines sent forth by the image of an object to the eye do not
reach the point within the eye in straight lines.
75.
If the judgment of the eye is situated within it, the straight lines
of the images are refracted on its surface because they pass through
the rarer to the denser medium. If, when you are under water, you
look at objects in the air you will see them out of their true
place; and the same with objects under water seen from the air.
The intersection of the rays (76-82).
76.
The inversion of the images.
All the images of objects which pass through a window [glass pane]
from the free outer air to the air confined within walls, are seen
on the opposite side; and an object which moves in the outer air
from east to west will seem in its shadow, on the wall which is
lighted by this confined air, to have an opposite motion.
77.
THE PRINCIPLE ON WHICH THE IMAGES OF BODIES PASS IN BETWEEN THE
MARGINS OF THE OPENINGS BY WHICH THEY ENTER.
What difference is there in the way in which images pass through
narrow openings and through large openings, or in those which pass
by the sides of shaded bodies? By moving the edges of the opening
through which the images are admitted, the images of immovable
objects are made to move. And this happens, as is shown in the 9th
which demonstrates: [Footnote 11: per la 9a che dicie . When
Leonardo refers thus to a number it serves to indicate marginal
diagrams; this can in some instances be distinctly proved. The ninth
sketch on the page W. L. 145 b corresponds to the middle sketch of
the three reproduced.] the images of any object are all everywhere,
and all in each part of the surrounding air. It follows that if one
of the edges of the hole by which the images are admitted to a dark
chamber is moved it cuts off those rays of the image that were in
contact with it and gets nearer to other rays which previously were
remote from it &c.
OF THE MOVEMENT OF THE EDGE AT THE RIGHT OR LEFT, OR THE UPPER, OR
LOWER EDGE.
If you move the right side of the opening the image on the left will
move [being that] of the object which entered on the right side of
the opening; and the same result will happen with all the other
sides of the opening. This can
An experiment, showing how objects transmit their images or
pictures, intersecting within the eye in the crystalline humour, is
seen when by some small round hole penetrate the images of
illuminated objects into a very dark chamber. Then, receive these
images on a white paper placed within this dark room and rather near
to the hole and you will see all the objects on the paper in their
proper forms and colours, but much smaller; and they will be upside
down by reason of that very intersection. These images being
transmitted from a place illuminated by the sun will seem actually
painted on this paper which must be extremely thin and looked at
from behind. And let the little perforation be made in a very thin
plate of iron. Let a b e d e be the object illuminated by the sun
and o r the front of the dark chamber in which is the said hole at n m . Let s t be the sheet of paper intercepting the rays of the
images of these objects upside down, because the rays being
straight, a on the right hand becomes k on the left, and e on
the left becomes f on the right; and the same takes place inside
the pupil.
[Footnote: This chapter is already known through a translation into
French by VENTURI. Compare his ' Essai sur les ouvrages
physico-math�matiques de L. da Vinci avec des fragments tir�s de ses
Manuscrits, apport�s de l'Italie. Lu a la premiere classe de
l'Institut national des Sciences et Arts.' Paris, An V (1797).]
The practice of perspective (72. 73).
72.
In the practice of perspective the same rules apply to light and to
the eye.
73.
The object which is opposite to the pupil of the eye is seen by that
pupil and that which is opposite to the eye is seen by the pupil.
Refraction of the rays falling upon the eye (74. 75)
74.
The lines sent forth by the image of an object to the eye do not
reach the point within the eye in straight lines.
75.
If the judgment of the eye is situated within it, the straight lines
of the images are refracted on its surface because they pass through
the rarer to the denser medium. If, when you are under water, you
look at objects in the air you will see them out of their true
place; and the same with objects under water seen from the air.
The intersection of the rays (76-82).
76.
The inversion of the images.
All the images of objects which pass through a window [glass pane]
from the free outer air to the air confined within walls, are seen
on the opposite side; and an object which moves in the outer air
from east to west will seem in its shadow, on the wall which is
lighted by this confined air, to have an opposite motion.
77.
THE PRINCIPLE ON WHICH THE IMAGES OF BODIES PASS IN BETWEEN THE
MARGINS OF THE OPENINGS BY WHICH THEY ENTER.
What difference is there in the way in which images pass through
narrow openings and through large openings, or in those which pass
by the sides of shaded bodies? By moving the edges of the opening
through which the images are admitted, the images of immovable
objects are made to move. And this happens, as is shown in the 9th
which demonstrates: [Footnote 11: per la 9a che dicie . When
Leonardo refers thus to a number it serves to indicate marginal
diagrams; this can in some instances be distinctly proved. The ninth
sketch on the page W. L. 145 b corresponds to the middle sketch of
the three reproduced.] the images of any object are all everywhere,
and all in each part of the surrounding air. It follows that if one
of the edges of the hole by which the images are admitted to a dark
chamber is moved it cuts off those rays of the image that were in
contact with it and gets nearer to other rays which previously were
remote from it &c.
OF THE MOVEMENT OF THE EDGE AT THE RIGHT OR LEFT, OR THE UPPER, OR
LOWER EDGE.
If you move the right side of the opening the image on the left will
move [being that] of the object which entered on the right side of
the opening; and the same result will happen with all the other
sides of the opening. This can
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