the pupil.

[Footnote: This chapter is already known through a translation into
French by VENTURI. Compare his '_Essai sur les ouvrages
physico-mathematiques de L. da Vinci avec des fragments tires de ses
Manuscrits, apportes 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