A screw-driven machine; water flows fastest at the surface
Red-chalk mechanism labelled screw (vite), 20 braccia; in pen, a law of river flow
A red-chalk drawing shows one of Leonardo's mechanisms - a roller and frame labelled a screw (vite) and a length of 20 braccia - with a fainter indeterminate figure beside it. In pen he records a law of flowing water: over an even bed and slope the current runs faster at the surface than at the bottom, and faster in the middle than at the sides. The page joins a mechanical device to his science of river flow.
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Kinematic device with a screw (vite), span 20 braccia
A red-chalk sketch lays out a mechanism mounted on a frame, labelled with a screw (vite) and a measure of 20 braccia. It is one of Leonardo's studies of moving mechanical parts.
Current is fastest at the surface and in the middle
Every motion of water over an even bed and slope is faster at the surface than at the bottom, and faster in the middle than at the sides. Leonardo describes the velocity profile of a uniform channel.