A 15-Pound Load on Three Cords: Dividing Weight by Proportion
The center m carries fifteen pounds shared among five proportional parts, 3/15 each
A single horizontal rod hung from three cords, each carrying square weights marked with numbers, is drawn at the top of the leaf. The note identifies m as the center of gravity of the whole suspended load of 15 pounds. Because the arrangement involves five proportional parts, the 15 pounds is divided into five, giving 3/15 to each part, a result confirmed by a fraction jotted in the margin.
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The point m as center of a 15-pound suspended load
Leonardo marks m as the center of gravity of the gravity suspended from the three cords, that whole gravity amounting to 15 pounds. It is the point at which the loaded rod hangs in balance.
Splitting 15 pounds into five proportional parts
Since the proportions number five, the 15 pounds is divided into five parts, giving 3/15 for each part. A marginal note records the matching fraction sum, 1 1/2 1/5 makes 3/15.