The motor of augmentative power, contrary to the crossbow
A weight m hung over five pulleys (middle pulley n), gaining impetus at every degree of fall
At the top a rectangular weight labelled m hangs by two corners from a cord looped around five pulleys set quincuncially, the central pulley marked n. Under 'On the motor of augmentative power,' Leonardo contrasts this motion with the crossbow's: this motor gains a degree of impetus at every degree of its motion, whereas the crossbow's cord begins in full force and ends in nothing. The falling counterweight, beginning in nothing, finishes in great power; the passage then begins to note that the crossbow's strong initial motion does not slacken the arrow's impetus, and breaks off.
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Augmentative power versus the crossbow's fading force
This motion is the contrary of the crossbow's, for the motor here acquires degrees of impetus at every degree of motion, while the crossbow's cord begins in its force and finishes in nothing. The falling counterweight, by contrast, begins in nothing and finishes in great power. Leonardo begins to note that the great motion the crossbow's cord makes at the start does not slacken the arrow's impetus, before the text breaks off.
Weight m on a five-pulley loop, middle pulley n
The sketch shows a rectangular weight labelled m suspended at two corners by a loop of cord running around five pulleys arranged quincuncially, the middle pulley labelled n. This falling-weight-and-pulley train is the 'motor of augmentative power' whose force grows throughout the fall.