Finding the centre of two suspended weights
Balance proofs using a rod where b c is a quarter of c e
Three balance diagrams explore where the centre of two suspended weights lies. A single rod carries weights marked 4 and 1, while a compound arrangement of linked rods bears weights at the labelled points m, f, n and a, b, c, d, e. Through two proofs Leonardo shows that f is the centre of the two attached weights, using the fact that segment b c is one quarter (subquadruple) of c e, so that a weight of 1 at e balances a weight of 4 at b.
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f as the centre of the two suspended weights
By two proofs Leonardo shows that point f is the centre of the two attached weights on a balance-beam. Taking the perpendicular at b, he notes that b c is a subquadruple (one quarter) of c e, so a single weight hung at e stands equal with a weight of 4 at b. The upper balance in the figure confirms the same result.