Notes and Drawings on the Thorax and Abdomen (1901) - Page 21

⚠The manuscript is written in Leonardo da Vinci's characteristic mirror script (right-to-left). The transcription provided below follows the Italian text as it was intended to be read (left-to-right), preserving the original early modern spelling and abbreviations where identifiable.

Conclusion on the impact of air

in the midst of water, or of water within air

Let air be one medium and water the other medium, and let the surface that divides them be flat; and let the impact be made by a stone or other heavy falling body original: "grave cadente" from the air into the water. I say that the motion of the water will not be of a single quality, but will vary according to the variety of the position where the aforementioned heavy body strikes. Because if the heavy body is round and strikes flatly, it will drive the water in every direction equally; and if the heavy body is oblique, it will drive the water more to one side than the other. And if the heavy body is flat and strikes flatly, it will drive the water in every direction equally; and if the heavy body is oblique, it will drive the water more to one side than the other. ...? motion of the air in the midst of the water, which will be of ...? and of ...? as is seen ...? impact of the water ...? will be made by the motion of the air ...? surface of the water. ...? of the air within the water ...? which moves? with a winding? motion.

Of the motion of light through media

of varying density or rarity

[A sketch of concentric, radiating curved lines] This sketch likely represents the propagation of waves or ripples following an impact. [A geometric diagram showing straight lines intersecting a horizontal line] A simplified study of a ray of light striking a boundary surface. [A complex diagram with intersecting rays and labeled points a, b, c, d, e, f] A detailed optical diagram illustrating the geometry of refraction.

Every luminous ray original: "razzo luminoso" that passes through the medium of air and water bends at the surface where such media join, and this happens because air is rarer less dense than water. And if the luminous ray passes from the rarer medium to the denser, it bends toward the perpendicular line of the surface of such a medium. And if the luminous ray passes from the denser medium to the rarer, it bends away from the aforementioned perpendicular. Let d be the light and let the eye be at a, and let bc be the surface of the water, and let de be the luminous ray that passes through the air; I say that at point e, where it enters the water, it bends toward the perpendicular ef. And if the eye were at g, it would see the light d at point h, that is, along the line gh, which is lower than the line ged.