71

The function of the eye as explained by the camera obscura.

[figure]

HOW THE IMAGES OF OBJECTS RECEIVED BY THE EYE INTERSECT WITHIN THE CRYSTALLINE 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-mathématiques de L. da Vinci avec des fragments tirés de ses Manuscrits, apportés de l’Italie. Lu a la premiere classe de l’Institut national des Sciences et Arts.’ Paris, An V (1797).]

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

70 * 72
I * III
. . .
Definition of Perspective.
Experimental proof of the existence of the pyramid of sight.
52,
53,
The relations of the distance points to the vanishing point.
55,
How to measure the pyramid of vision.
The Production of pyramid of Vision.
58,
59,
60,
61,
62,
63,
Proof by experiment.
65,
General conclusions.
That the contrary is impossible.
A parallel case.
The function of the eye as explained by the camera obscura.
70,
The practice of perspective.
72,
Refraction of the rays falling upon the eye.
74,
The inversion of the images.
The intersection of the rays.
77,
78,
79,
80,
81,
Demomstration of perspective by means of a vertical glass plane.
83,
84,
The angle of sight varies with the distance.
86,
87,
Opposite pyramids in juxtaposition.
On simple and complex perspective.
The proper distance of objects from the eye.
. . .

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