Percussion, the Spring, and the Swing
Whether many blows of power 10 equal one great blow of 500 pounds
Written with the sheet turned on its side, this leaf studies percussion and the accumulation of motion. Leonardo asks what is gained by repeatedly moving a suspended weight, and whether a weight of 10 struck with a power of 10 against a spring behaves like a weight of 1000 driven by the same power. In the main note he compares pushing a man on a swing: each push of force 10 carries the weight a little further (a to b and back to c, c to d and back to f, and so on) until fifty pushes build up a circular motion worth 10 times 50, i.e. 500 — and asks whether 500 pounds delivered at a single stroke would do the same. The sketches show a radiating fan of swing positions at the top, a framed spring-and-weight mechanism, and a small hanging weight.
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A weight of 10 versus a weight of 1000 against a spring
If a weighs 10 and I move it to strike with a power of 10, producing a certain quality of blow, then if a weighs 1000 and is moved by the same power of 10 against a spring of equal resistance, what more will the blow do than the first, given that the mover always handles the spring with a power of 10?
Fifty pushes of the swing add up to 500
One pushing a man on a swing sends the weight a with force 10 to b, and it returns almost to c; then from c to d and back to f, then thrust from f to g and back to h, and so on until it makes circular motion 50 times with that power of 10 — in sum 10 times 50, i.e. 500. Would 500 pounds joined together at one stroke do the like?
The gain from repeatedly moving a weight on a cord
Beside the topmost figure, marked 'a 10', Leonardo notes that he wishes to know the gain of the thing, repeating in motion a weight hung on a suspended cord, that is ... (the note breaks off).
Framed spring-and-weight striking apparatus
At the centre of the sheet a mechanism is drawn as two framed uprights carrying a hanging weight, illustrating the spring against which the striking weight is driven in the percussion problems noted alongside.