How a weight loads its support
Horizontal, perpendicular and oblique props, with equal numbers on each arm
Leonardo states that any weight whose descent is impeded loads itself wholly on its support, and that the support's behaviour depends on its orientation: along a horizontal line the part farther from the fixed point resists less; along a perpendicular the weight bears whole throughout its height without varying the base; along any other line the foot is burdened not only by the weight but by its lever. A numerical example distributes 5 libbre and 3 across a balance so that the degrees of weight and of arm sum to 8 on each side of the pole, showing that the arms stand level when weight and space give equal, doubled numbers. A small figure shows a graduated arm with a hanging load and a triangular prop.
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A support burdened by weight and by its lever
Every weight whose descent is impeded loads itself entirely on its support. If the support is horizontal, the part farther from its fixed point resists less, changing a degree of weight at every degree; if perpendicular, the weight on its head is whole throughout its height; in any other line the foot is burdened not only by the weight but by its lever.
Equal numbers of 8 on each side of the pole
Attaching 5 libbre and 3 at 2 braccia, Leonardo chooses 5 and 3 spaces so the degrees of weight and of arm make equal numbers that resist one another. On this side of the pole, 5 degrees of weight and 3 of arm make 8; on the far side, 5 degrees of arm and 3 of weight also make 8, so the arms stand level when the numbers are equal and doubled.
Graduated arm with load and triangular prop
A small figure at the upper left shows a graduated horizontal arm with a ring-hung load and a triangular support beneath it. The drawing illustrates the prop or 'sostentaculo' whose loading the text analyses.