The science of weights, with simple and compound perspective
A balance proof that a freely falling weight burdens no support
The upper text defines simple perspective, made on a plane every part of which is equally distant from the eye, against compound perspective, where no part is equally distant, then opens a section 'On the science of weights.' Below, a balance diagram labelled d, m, a, b, c with the numbers 1 2 2 supports a short proof that a heavy body descending freely lends no weight to any support. Because the excess weight at b has nothing to hold it at a, it falls free, so the arm's end m does not feel it. The lower half of the leaf is left blank.
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A freely falling weight gives nothing to its support
On a balance where a weighs one and b weighs 2, the end m sustains only 2. The single unit of excess at b, having nothing to hold it at a, descends freely; being unsupported, its motion is not impeded, so the arm's end m never feels that excess.
Simple versus compound perspective
Simple perspective is made by art upon a plane every part of which is equally distant from the eye. Compound perspective is made upon a plane no part of which is equally distant from the eye.