Studies of water.
“All the branches of a water [course] at every stage of its course, if they are of equal rapidity, are equal to the body of the main stream.[*]”
Among Leonardo's drawings are many that are studies of the motion of water, in particular the forms taken by fast-flowing water on striking different surfaces.
Many of these drawings depict the spiralling nature of water. The spiral form had been studied in the art of the Classical era and strict mathematical proportion had been applied to its use in art and architecture. An awareness of these rules of proportion had been revived in the early Renaissance. In Leonardo's drawings can be seen the investigation of the spiral as it occurs in water.
There are several elaborate drawings of water curling over an object placed at a diagonal to its course. There are several drawings of water dropping from a height and curling upwards in spiral forms. One such drawing, as well as curling waves, shows splashes and details of spray and bubbles.
Leonardo's interest manifested itself in the drawing of streams and rivers, the action of water in eroding rocks, and the cataclysmic action of water in floods and tidal waves. The knowledge that he gained from his studies was employed in devising a range of projects, particularly in relation to the Arno River. None of the major works was brought to completion.
[*] Jean Paul Richter editor 1880, The Notebooks of Leonardo da Vinci Dover, 1970
Fuente: Science and inventions of Leonardo da Vinci, from Wikipedia, the free encyclopedia.