Screw-driven toothed wheels and a diamond-tipped drill
Worm-gear drives, a great arc-tracer, and an underwater boring tool
This verso is crowded with mechanisms: at the upper right a stacked series of worm-and-wheel drives, in the center horizontal shafts with cranks, and at the lower left a large horizontal disc bearing a weighted vertical drill. The heading names the theme, toothed wheels and pinions driven by a screw, and a note observes that such a screw-driven wheel is easier for its mover the slower its motion, provided the screw has strong resistance against the pivot set opposite where the wheel tends to run. Further notes describe a great arc (centina) of a circle two hundred braccia across, traced with linked rods, and a tempered-steel drill tipped with a lentil-shaped diamond driven by a lead weight to bore under water. Letters a, n and the label "polo" mark parts of the figures.
On this page
Toothed wheels and pinions driven by a screw
The page treats wheels and pinions (rote e roche) driven by a screw, drawn at the right as stacked worm-and-wheel pairs. A wheel moved by a screw must have strong resistance against the pivot placed opposite the point where the wheel tends to run away with its motion; the letters a, n mark the arrangement.
The slower the motion, the easier for the driver
Leonardo notes that a wheel moved by a screw is easier for its mover the more sluggish (slower) its motion is, and adds that this holds for every kind of motion.
A diamond-tipped tempered-steel drill for boring under water
The drill must be of tempered steel, tipped with a diamond wider than the drill's point and thick in the middle like a lentil so it stays in its setting. A lead weight drives it, and the note "sotto l'acqua" shows the tool is meant to bore under water.
Tracing a great arc of two hundred braccia
A centring arc (centina) is described as part of a circle two hundred braccia across, laid out with linked rods fixed at great height, on a tower or the like, or worked along the ground on carts as they move through the arc.