VENI VIDI DA VINCI

Collections Newsletter Guild About Developers Patron Sign In

Library/Paris Manuscript F/180

Prev180 / 200Next

Paris Manuscript F — 180

100%

Reset zoom

Bibliothèque de l'Institut de France, Paris

L'obbietto laterato1 interposto per obbliquo nel mezzo del corso dell'acq[ua]: ancora che l'acqua percota nel suo lato piano, essa andrà con maggior somma in verso il lato d'essa obbliquità più bassa, cioè2 più in a che in b.

Figura rettangolare d'ostacolo investito dall'acqua, con:

a b

Dell'aria.

L'aria3, sotto il mobile che per quella discende, si fa densa e di sopra si rarefa. E perché, com'è provato nella settima non essere inconveniente all'aria il condensarsi e rarefarsi quasi 'n un istante (il che non si trova possibile nell'acqua stando nella sua forma)4, egli è più facile all'aria laterale e superiore al mobile, che in fra essa discende, riempiere il vacuo da esso mobile sopra sé di sé lasciato, che l'aria di sotto a piegarsi e per linia curva e lunga moversi al riempimento di tal vacuo; ancora è impossibile per la ottava, che prova che ogni impeto creato nell'aria move con seco essa aria per la linia della creazion d'esso impeto; come il vento che tanto move d'aria, quanto il suo empito si move, come si vede nella polvere mossa da tali venti o nelli attimi nella spera del sole, quando in quelli è soffiato5. Adunque: l'aria, sospinta dall'empito del grave che per essa discende, fugge per la linia del moto fatto dal suo motore, e la laterale si converte in retrosi laterali, e la superiore li6 discende di sopra, sempre riempiendo il vacuo che tal mobile lascia di sé sopra di sé, in ogni grado del suo movimento.

An angled object set obliquely in a current

The sided object interposed obliquely in the midst of the course of the water: although the water strikes on its flat side, it will run with the greater quantity toward the side of its lower obliquity, that is, more into a than into b.

Rectangular figure of an obstacle struck by the water, with: 'Of the air'

a b. Of the air. The air, beneath the moving body that descends through it, becomes dense, and above it becomes rarefied. And because, as is proved in the seventh, it is no hindrance for air to condense and rarefy almost in an instant (which is not found possible in water while it stays in its form), it is easier for the lateral and upper air, around the body descending among it, to fill the void left above itself by that body, than for the air below to bend and, by a curved and long line, move to fill that void. Moreover it is impossible by the eighth, which proves that every impetus created in the air moves that air with itself along the line of the creation of that impetus, like the wind, which moves as much air as its impetus moves, as is seen in the dust stirred by such winds, or in the motes within the sunbeam when one blows into them. Therefore the air, pushed by the impetus of the heavy body descending through it, flees along the line of the motion made by its mover, and the lateral air turns into lateral eddies, and the upper air descends from above, always filling the void that the moving body leaves above itself, at every degree of its movement.

Water Against an Oblique Obstacle; Air Behind a Falling Body

Flow deflected to the lower side, and how air condenses and eddies around a descending weight

Hydraulics Physics & Mechanics

The page opens with a rule about an angled object set obliquely in a current: though the water strikes its flat side, most of the flow runs off toward the lower, more oblique edge, more into a than into b, illustrated by a rectangular obstacle met by water. Leonardo then turns to the air around a body falling through it, arguing that the air condenses below the moving body and rarefies above, and that the void left behind is filled more easily by lateral and upper air than by air bending up from below. Citing his own earlier propositions on impetus, he concludes that the displaced air flees along the line of motion, the sides turning into lateral eddies while the upper air descends to fill the void at every stage of the fall. A small sketch appears at the upper right of the sheet.

On this page

Current deflected toward the lower oblique edge

An angled object set obliquely in the midst of a current is struck by the water on its flat side, yet the greater quantity of flow runs off toward the side of its lower obliquity, that is, more into a than into b. The rectangular obstacle met by the water is drawn on the sheet.

Air condensing, rarefying and eddying around a falling body

Beneath a body descending through air the air becomes dense, while above it rarefies; since air can condense and rarefy almost instantly, the void behind the body is filled more easily by lateral and upper air than by air bending up from below. Invoking his earlier propositions on impetus, Leonardo notes that every impetus in air carries that air along its line, as seen in dust raised by wind or motes in a sunbeam when blown. The displaced air therefore flees along the line of motion, the sides turning into lateral eddies and the upper air descending to fill the void at every degree of the fall.

Reader's Edition — described with AI from the e-Leo transcription.