The motion of wind and water, and painting a mountain-fall
How to reveal wind eddies with smoke, trees bent by the wind, and how to depict a mountain crashing upon a city
Leonardo studies the movement of air and water, proposing a test in which cotton is packed into a cane tube and smoke blown through it to reveal the enveloping eddies of the wind, and observing how water descending from mountaintops grows turbulent and carries off stones and timber. Beneath the prose are sketches of swirling vortices, tumbling stones in the wind, and a rod thrust into a whirlpool. On the right, in his own hand, is a painter's instruction for depicting a mountain falling upon a city, distinguishing the colours of dust, rain, smoke and flame, to be treated fully in the book on painting. A marginal pencil note mentions bombards.
On this page
Revealing wind eddies with smoke
To see the course of the wind in the air and its enveloping eddies, pack cotton into a tube of cane and blow smoke through it from one end; the wind and smoke issuing from the other end demonstrate the entanglements sought in the motion of the wind.
Mountain water grows turbulent as it falls
Water descending from the tops of the mountains to their feet gains, at every degree of descent, a degree of turbulence and of plunder, carrying off various stones and diverse timbers. United water falling through the air moves unequally, the parts farther from its central line descending more slowly because they are more mixed with air and so lighter.
How to paint a mountain falling on a city
A mountain falling upon a city raises dust like clouds; the colour of the dust should differ from that of the clouds. Where rain is thickest the dust shows less, and where dust is thickest the rain shows less; where flames mix with clouds of smoke and water, dark and very opaque clouds are formed. The rest is to be treated in the book on painting.
Trees bending and rebounding in the wind
Trees struck by the course of the winds bend toward the place whither the wind moves, and once the wind has passed they bend back in the contrary, rebounding motion.
A rod moved against still water
Beside a figure of a rod in a whirlpool: a rod moved against still water behaves just as running water does against a still rod. A neighbouring figure notes that a stone drawn through the air leaves in the eye an impression of its motion, as do raindrops falling from clouds.
Pencil note on bombards
Two lines in pencil record bombards from Lyon to Venice, by the method Leonardo says he gave at Gradisca in the Friuli and elsewhere.