Water Falling Free Through Air versus Falling in a Conduit
How a stream narrows as it drops, empties the pipe, and is impeded by condensed air
This mirror-written red-chalk page, with a small red diagram of a descending stream at the upper right, asks how the percussion of one and the same water differs when it falls freely through the air as against falling enclosed in a conduit. Leonardo observes that water falling along a perpendicular line becomes pointed at part of its descent while the conduit above it is left empty, so that air struggles against the water. He adds that such a fall is impeded by the condensation of the air trapped within the conduit.
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Free fall versus enclosed fall of water
Leonardo compares the percussion of water dropping openly through the air with that of water falling clothed within a conduit. The falling stream narrows to a point in part of its descent, and the conduit from which it fell is left empty.
Air condensing in the pipe impedes the fall
Where the water leaves the conduit empty, the air fights against the water. Leonardo notes that the descent is impeded by the condensation of the air within the conduit of that water.