Axle natures; why a multiplying wheel hinders water-raising
Long or short, thick or thin axles, and the useless 'wheel of augmentation'
The page catalogues the natures of axles (poli), long or short, thick or thin, tapering from either end, with small cross-sections sketched in the right margin. Its main argument concerns a water-raising machine: Leonardo says the 'wheel of augmentation' (a multiplying wheel) is not useful here but actually makes the work harder, since besides lifting water in the pump by your own counterweight you must also keep that wheel turning with your weight, which tires a man as any unimpeded wheel does. Mechanisms are drawn, including a corded drum, a framed toothed wheel with crank marked 'stable pivot' and 'immovable pivot,' and a treadle-and-beam device, with points lettered m, 10, 10, n.
On this page
Natures of the axle (polo)
Leonardo distinguishes axles by length, long or short, and by section: thick or thin, thick at one end and thin at the other, or the reverse. Small profiles in the right margin illustrate the variants.
The multiplying wheel makes water-raising harder
He judges that here the 'wheel of augmentation' is not useful but adds difficulty: besides raising water in the pump with your own weight as counterweight, you must also sustain the wheel's motion, which tires a man just as turning any unimpeded wheel does.
Framed wheel lettered m, 10, 10, n
A toothed wheel in an upright frame carries a crank and linkage; its bearings are labelled 'stable pivot' and 'immovable pivot,' and points along the lower bar are marked m, 10, 10, n.