On Equal Powers and the Descent of Weights
Balances, cords and pulleys with theorems that a descending weight cannot raise an equal load to its own height
The upper fragment carries balance diagrams and transversal sketches of cords, weights and pulleys, surrounded by repeated statements of two mechanical theorems. Leonardo insists that equal powers resist one another equally and can never set each other in motion, and that a gravity which descends can never, in the time of its descent, raise a weight equal to itself back to the height from which it fell. He distinguishes 'simple', 'compound' and 'augmented' power, and notes for one cord diagram that a right angle 'uses the truth' while an acute angle behaves otherwise. The lower fragment (b) bears no writing.
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Equal powers cannot move one another
Distinguishing simple, compound and augmented power, Leonardo states it is impossible that equal powers can, in equal time, give equal motions one to the other, and that equal powers resist one another equally and can never of themselves give motion one to the other.
A descending weight cannot re-raise its equal in equal time
A gravity that descends will never raise a weight equal to itself to the height from which it descended in the same time as its descent. It is likewise impossible that in equal time a weight can raise another as much as it itself descends.
Cords, weights and pulleys; right versus acute angle
Among transversal drawings of cords, weights and pulleys, one is lettered b r - n - S c. Leonardo notes that the right angle c b 'uses the truth', while the acute angle n c r behaves as if it were S.