Water-wheels: falling water versus the weight of the wheel
Proportional weights on circular wheel diagrams; the fall a b compared with d c
Five notes set beside circular water-wheel diagrams argue about the power of falling water. Leonardo assigns proportional weights to the water and the wheel — labelled 'double' and 'eleven-fold' proportion — and asks whether the vertical fall a b or the oblique fall d c is more powerful when both drop the same height. He concludes that a mill wheel turns more easily by its lightness than its heaviness, and is the more powerful the more the water's weight exceeds the wheel's, as in bucket-wheels (rote a cassette). Faint mechanism and landscape sketches also cross the leaf.
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Vertical fall a b versus oblique fall d c
Beside the wheel diagrams Leonardo asks which is more powerful, the fall of water a b or the fall d c, when both drop the same height. He answers that although the run c d is longer, it is lighter for being oblique.
A mill wheel driven more by water's weight than its own
He argues that a mill wheel is easier to turn by its lightness than by its heaviness. It is the more powerful the more the water's weight exceeds the wheel's, and weaker as the wheel outweighs the water, understood of bucket-wheels (rote a cassette).
Proportional weights: double and eleven-fold
The circular diagrams are annotated with paired numbers giving the ratio of water to wheel, labelled 'double proportion' and 'eleven-fold proportion.' These figure the balance of forces Leonardo is weighing.
The heavier body follows the motion more
A short note by the left-hand wheel states that of things moved along any line, that which is heavier will follow the motion more.
Bucket-wheel and frame at lower right
At the lower right the sheet carries a drawing of a wheel fitted to an inclined frame, apparently a bucket-wheel of the kind the notes describe. Faint mechanism and landscape sketches also appear across the leaf.