The Manuscripts of Leonardo da Vinci, Vol. 4 (1881) - Page 20

[WATER (VORTICES). — PLANKS].

2. — This vortex original: "retroso" — Leonardo uses this term for whirlpools or circular water movements. does not have a fixed position —
[ Figure : ] e a b c d
Because a b is lighter than c d, a b cannot provide as much water as c d consumes; therefore, by necessity, air enters through c d into the space of the quantity of water that represented the difference between the water previously in c d and a b, and thus the water c d remains equal to the weight of the water a b.

Thin, wavy boards can be made of wood that will resemble camlets camlet: a costly historical fabric, often made of silk and camel hair, known for its luster and tabis tabi: a "watered" silk or moiré fabric with a wavy pattern and various permanent markings.

On surface vortices and those created at various depths of water; and those that take up the entire depth; and the mobile ones, and the stable ones. On the long and the round ones. On those that change their motion, and those that divide, and those that turn into the ones they join, and those that are mixed with falling and reflected water which keep that water turning.

Which are the vortices that rotate light objects on the surface and do not submerge them. Which are those that submerge them and rotate them on the bottom and then leave them on that bottom. Which are those that detach things from the bottom and throw them back to the surface of the water. Which are the oblique vortices, which are the straight, which are the flat.

2. — This water vortex has no steady position.
[ Figure : ] e a b c d original: 1. 2..
Because a b is lighter than c d, a b cannot provide as much water as c d consumes; therefore, by necessity, air enters through c d in place of a quantity of water equal to the difference of the water that was at first more in c d than in a b, and so the water c d remains equal to the weight of water a b.

One can make, from wood, thin wavy planks that will look like camlets and tabis, and with various stable stains.

On surface vortices and those [which are] created at various heights of the water. Of those that take up all that height, and the mobile ones, and the stable ones. Of the long and the round ones. Of those that change motion, and those that divide, and those that turn into those they join, and those that are mixed with falling and reflected water, and make it turn.

Which are the vortices that make light things rotate on the surface and do not submerge them. Which are those that submerge them and make them rotate on the bottom, and then leave them at that bottom. Which are those that detach things from the bottom and throw them back to the surface of the water. Which are the oblique vortices, which are the straight, which are the flat.

1\. Under the figure, there are some lines and, under the texts in ink down to the word "Which," there are drafts in red chalk. 2 and 3. See: Cardinali, eighth book, chapter XLVII, p. 430, and plate 32, fig. 183. This refers to a later scholarly edition of Leonardo's works.

[PLAN FOR THE TREATISE ON WATER. — SWIMMING. — SHIPS].

When you assemble the science of the motions of water, remember to place under each proposition its practical applications, so that such science is not useless —

On the utility of the choices original: "partiti" — refers to the decisions or tactical maneuvers a person must make. that the swimmer must make regarding the surface eddies of the waters and their vortices which submerge those swimmers. And then, once he is submerged, how he must manage to save himself, and so on. And at the end of each book, observe more remarkable things, such as how to break through the thickness of vortices in any direction. On the choices one must make when swimming in sea waves, and the impact of rocks, and the steering of ships.

In putting together the science of the movements of water, remember to put under each proposition its helpers referring to practical applications or supporting proofs, so that such science is not useless.

On the utility of the decisions the swimmer has to take in relation to the surface turnings of the waters and their vortices, which submerge these swimmers. Then how he must govern himself when he is submerged, to save himself, and so on. And at the end of each book, observe more remarkable things, such as breaking the thickness of the vortices in any direction. Of the decisions that must be made while swimming in the waves of the seas, and how to avoid the strikes of the reefs and the governing of ships.

1\. Under the first paragraph, a draft in red chalk: "when you assemble the science of the motions of water have awareness... the benefit... so that such science is not useless." — The figure that follows is also in red chalk.