Balance with pyramidal arms; distinguishing weight from cord-force
Equal weights of 4 on the arms, plus gear trains turning one way
The upper diagrams show a balance beam with 'pyramidal arms' from which equal weights of 4 and 4 hang at points a, b, c, d, together with a semicircular array of weights suspended by cords at differing obliquities. Leonardo insists on counting only the simple weights here, so that the weight 4 at c equals the weight 4 at n, while deferring the 'force' the slanting cords exert on their supports, which loads and strains them but does not itself weigh. Below, a gear-and-belt train is noted as turning all its wheels in one same direction.
On this page
Simple weight versus the force of the cords
Here only the simple weights are counted, not the force the cord-ends exert on their supports: the weight 4 at c is equal to the weight 4 at n. Although the cord that sustains it strains and loads its supports, that force does not weigh, so it is reckoned separately from the plain weight. The beam is drawn as a balance with its pyramidal arms.
Wheel train turning one way
The gear-and-belt train drawn at the foot of the page is noted as having all its wheels turn in one same direction.