Pigment prices, balances and relative motion
Friction of cart axles, the qualities of balance arms, a shopping list of colours, and apparent motion.
Under transmitted light the left leaf (228v) is crowded with diagrams of balances, levers and pulleys, while the right leaf (227r) carries a priced column of materials. The notes treat how thick cart axles heat up far more than thin ones through friction, the three qualities of balance arms (equal, unequal by nature, unequal by position), and how a balance's arms become unequal once in motion. The right leaf lists quantities and prices of a painter's supplies - azure of Germany, white lead, cinnabar, green, yellow, red lead, ochre, black stone, wax and oil - totalling 120 lire 18 soldi, and a closing note observes that a slower body seen beside a faster one appears to move backward, as with clouds against the sun or boats at sea.
On this page
Thick cart axles heat more than thin ones
In one turn of a wheel a mark on a thick axle-pin is rubbed by a whole braccio of its housing, but on a thin pin by only one eighth, so the thick pin heats far more. Friction is treated as proportional to the surface swept.
Three qualities of balance arms
Balance arms are said to be of three qualities - equal, unequal by nature, and unequal by position - while the poles admit three variations (above or below the beam) and two kinds of support (with a pendicle or without). The letter-marked figures show how weights are equalized.
Priced list of a painter's materials
A running account prices out azure of Germany at a ducat the pound, 60 pounds of white lead, cinnabar, green, yellow, red lead, ochre, black stone, wax for making the stars, and 40 pounds of painting oil, summing to 120 lire 18 soldi apart from the gold and the tin for attaching it.
Colours and oils for painting
The same list is effectively an inventory of a painter's palette and media - azure, white lead, cinnabar, green, yellow, red lead, ochre and black stone, with oil for painting and wax for the stars - naming the pigments Leonardo intended to buy.
The slower body seems to move backward
When two things move the same way and one is faster, the slower seems to move in the opposite direction when there is no fixed thing to compare it with. Leonardo instances clouds that move like the sun or moon toward the west, and boats on the open sea against the horizon of air and water.