Well-bucket hoist with pulley, winch and gear ratios
A well hoist with two-groove pulley and winding drum, plus gear-ratio sums and notes on river water
The sheet designs a hoist for drawing water from a narrow well, with a tub-shaped bucket ('secchia'), a two-groove pulley and a winding drum ('subbio'). Leonardo gives the bucket's dimensions, notes it need not have a guide, and shapes its mouth like a tub so it takes less room in the well. He works out the ratios between the wheel and the drum, one braccio of the drum's rope worth eight on the wheel, backed by columns of arithmetic. At the top, chapter headings in charcoal set out topics on water from surface to bottom and from bank to bank, and an inverted corner sketches a scheme for friction.
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A narrow tub-shaped bucket for a tight well
Labelled a. The point a is the mouth of the bucket, made in the manner of a tub ('bigoncia') so that, being narrow, it takes up less room in a narrow well. The bucket should go four braccia under water. A two-groove pulley is drawn with it. Elsewhere the bucket is given as one braccio wide, 1 2/3 braccia high and 1/3 thick, and is said to need no guide.
Ratio of wheel to winding drum
The wheel turns 16 braccia while the drum is 2 braccia around, so in 6 turns it gathers 96 braccia of rope while the drum unwinds 12. For every 2 braccia the small wheel unwinds the great one unwinds 16; thus 10 braccia off the drum answer to 80 on the wheel, and each braccio of the drum's rope is worth 8 on the wheel.
Chapter headings on the behaviour of water
In charcoal at the top stand headings for a treatise on water: of the water from surface to bottom; of the changes of the water from one bank to the other; of the minglings of the waters.
A scheme for friction
In the inverted upper-left corner a lettered scheme addresses friction, with points marked e 6, f 3, a 1 1/2, d 4, c 2, b, and the beginning of a calculation: here I have from a to f, which are 2 1/2...