Water moves air: heavy and light contend in a sealed tube
On why the enclosed air rises through water into an oval, since nature grants no vacuum.
A single leaf whose long passage argues that a heavy liquid moves a light one - water moves air. Leonardo describes an inverted vessel c d in which air rising from d to b and water sinking contend, since nature grants no vacuum and the lighter always seeks to stand above the heavier; the surrounding water squeezes the trapped air into an oval as it escapes upward. He concludes that the true cause is the 'awakening' of weight and lightness that had slept while each element lay in its own place, and that no element has weight or lightness within its own sphere. The tall double-bulbed vessel drawn at the right matches this tube; further untranscribed writing and a sectored semicircle run across the top of the sheet.
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The contest of heavy and light, and nature's dread of a vacuum
Water wanting to descend and air wanting to rise contend within the inverted vessel, and neither can act without the other because nature grants no vacuum. Weight and lightness, annulled while each element lay among its own kind, are 'awakened' the moment the lighter is trapped beneath the heavier; and no element, Leonardo adds, has weight or lightness within its own sphere.
Air rising through water is squeezed into an oval in the tube
In the vessel c d the air a stood at d and the water at c until, on turning the vessel over, the air departed from d and rose to b. The lateral water clothing the air weighs more than that above it, for it is longer and it constrains the escaping air into an oval figure as it forces its way upward.