77

The intersection of the rays.

[figure][figure][figure][figure]

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 be proved by the 2nd of this which shows: all the rays which convey the images of objects through the air are straight lines. Hence, if the images of very large bodies have to pass through very small holes, and beyond these holes recover their large size, the lines must necessarily intersect.

[Footnote: 77. 2. In the first of the three diagrams Leonardo had drawn only one of the two margins, et m.]

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

76 * 78
I * III
Notebooks of Leonoardo da Vinci
II: Linear Perspective.
. . .
How to measure the pyramid of vision.
57
The Production of pyramid of Vision.
58,
59,
60,
61,
62,
63,
64
Proof by experiment.
65,
66
General conclusions.
67
That the contrary is impossible.
68
A parallel case.
69
The function of the eye as explained by the camera obscura.
70,
71
The practice of perspective.
72,
73
Refraction of the rays falling upon the eye.
74,
75
The inversion of the images.
76
The intersection of the rays.
77,
78,
79,
80,
81,
82
Demomstration of perspective by means of a vertical glass plane.
83,
84,
85
The angle of sight varies with the distance.
86,
87,
88
Opposite pyramids in juxtaposition.
89
On simple and complex perspective.
90
The proper distance of objects from the eye.
91,
92
eye.
93,
94,
95,
96,
97
. . .