Three Weights on a Rod and the Law of the Lever
The cord on the shorter arm bears as many times the weight as it divides into the longer
A single rod hung from cords carries three square weights lettered a, n and r, drawn at the top of the leaf. Leonardo states that m is the center of gravity of the three weights, and gives the underlying lever principle. One compares how many times the shorter arm goes into the longer, and if it goes in six times, the cord on the short side bears six times as much weight as the cord on the long side. Further lines of mirror-script continue lower down the leaf.
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m as center of three suspended weights
The point m is declared the center of gravity of the three weights a, n and r hung along the rod. It is the position at which the rod, loaded by its three cords, would hang in balance.
Inverse proportion of arm length to load
Leonardo directs the reader to see how many times the lesser part goes into the greater. If the lesser goes six times into the greater, then the cord on the lesser (shorter) space sustains six times as much weight as the cord on the greater space, the inverse relation of the lever.