Descent of a Heavy Body and the Eddying Air Around It
A falling weight gains a degree of heaviness at each degree of motion
Leonardo argues that a freely descending heavy body acquires one degree of weight at each degree of its motion, reasoning that a body falls the more heavily the less resistance it meets. He likens the air beneath a falling object to a wave of water, an eddying wave that is driven ahead on one side and drawn along on the other, so helping to push the body downward. Because the air escapes before the descending weight it offers no resistance, the motion endures longer and the last wave recedes ever farther. A small pen sketch of a falling spherical body accompanies the argument, with curved strokes standing for the eddying waves of air.
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A heavy body gains one degree of weight per degree of motion
A freely descending heavy body acquires one degree of weight at each degree of motion. This follows from the principle that a body is the heavier the less resistance it has, so as the fall continues its effective weight grows.
The eddying wave of air offers no resistance and prolongs the fall
The air escaping before the descending weight shows that it does not resist and so does not impede the motion. The more the wave descends, moving faster than the body that sets it going, the longer the fall lasts and the farther the last wave recedes, preparing the air touching the weight for an easier passage. A small sketch of a falling sphere marks the eddying air.