How Elements Weigh in Motion; Air Drawn from a Vent
Physics of weight and water, a note on lustrous black tending to blue, and a lettered air-vent device.
The left folio carries a dense note arguing that no element weighs upon itself but upon those lighter or heavier than it, and that motion changes this, so that water is lifted from the bottom only when it moves. Two lettered sketches follow: one on wind taken at a b and on how lustrous black inclines toward blue, another on an air-vent (isfiatatoio) at a and the difference between drawing air from a or from b. The facing folio bears only the name 'Benedetto'.
On this page
No element weighs upon itself except in motion
Leonardo reasons that an element has no weight within itself, weighing only upon a lighter body and less upon a heavier one; but in motion the light body weighs both on itself and on the heavier.
Water lifted from the bed by motion
Because motion alters weight, water rises from the bottom when it moves and does not press upon the bed when still; hence the weeds on the bottom do not bend and the mud does not pack together.
Lustrous black inclines toward blue
A lettered figure carries the observation that the highlight of a shining black surface leans toward blue. Alongside it a note reads that wind will be taken at a b, this being lighter than the c d that draws it. Diagram labels: a, b, c, d.
Drawing air through a vent at a
A second lettered figure marks an air-vent at a and asks what difference there is between drawing the air from a and from b, and whether the weights differ when a is open. Diagram labels: a, b.