On Motion and Weight: the Lever and a Water-Pressure Test
Lever and counter-lever in proportion; stacked stone driving water higher through a siphon
Under the heading 'On motion and weight,' Leonardo sets down that the length of a lever bears the same proportion to its counter-lever as the weights they carry, and likewise their slowness of motion and the paths their ends describe about the pivot. Diagrams show a weighted arm braced by a diagonal beam turning about a pivot, and a balance with a small weight labeled 1 level with pivot b and a larger weight 21 hung near a on the other arm. A hydraulic experiment fills the lower part of the page: a column of eleven one-braccio blocks of stone (a to b) pressing on one braccio of water (b to c), with a siphon rising to the top. He argues that a weight pressing a smaller quantity of water beneath it drives that water higher, so eleven braccia of stone over one of water would cast it eleven times higher than the length e n, which bears only one braccio of stone.
On this page
Lever and counter-lever in proportion to their weights
The proportion of the length of the lever to that of its counter-lever equals the proportion of their weights, and likewise of the slowness of their motion and of the paths made by each of their ends when they reach the fixed height of the pivot. The balance drawing carries the labels a b and the weights 1 and 21.
A weighted arm turning about its pivot
Near the upper right a vertical support carries a horizontal beam braced by a diagonal beam, with a rectangular weight at the beam's end. A thick dot at the junction marks the pivot, and an arc of a circle shows the path the weight would describe about that pivot as it falls.
Stacked stone drives water higher through a siphon
A vertical column of eleven one-braccio blocks of stone runs from a down to b and presses on one braccio of water between b and c, with a siphon leading from the foot of the water up to the top block. A companion horizontal version labels the stones d and e and the water down to n. The weight pressing a lesser quantity of water beneath it drives that water higher above itself.
The support shown bending sideways
A diagrammatic view isolates the vertical rectangular support of the first figure, without its horizontal and diagonal beams. It is drawn bending to one side, as the weight in the first figure would cause it to.