Leonardo da Vinci designed water wheels with blades arranged around a central wheel to capture moving water.
Water wheels were already ancient machines when Leonardo studied them, so he was not their inventor. His contribution was the detailed analysis and refinement of hydraulic machinery. In his notebooks, he examined water flow, wheel shapes, gearing, and ways to transfer rotary motion to pumps or other equipment.
A water wheel converts the energy of flowing or falling water into rotation. Depending on its design, water may strike the wheel from below, at the side, or from above. Leonardo's engineering drawings explored these arrangements and the relationship between water movement and useful mechanical work.
This subject is sometimes confused with Leonardo's studies of the Archimedes' screw, which lifts water through a rotating helical surface rather than using a wheel to capture water power. The broader significance of Leonardo's water-machine drawings is their combination of observation, geometry, and mechanical transmission.