Leonardo da Vinci proposed a water wheel for generating continuous motion from falling water.
Water wheels convert the energy of moving or falling water into rotation. Leonardo studied their blades, buckets, shafts, and gear connections, and designed variations intended to make hydraulic power useful for mills and other machines. His notebooks contain detailed observations of water flow and mechanical transmission.
Leonardo did not invent the water wheel. Water-powered wheels were used in the ancient world and were widespread in medieval Europe before his lifetime. His importance lies in the systematic way he analyzed their operation and explored improved mechanisms.
A water wheel is not the same as a modern hydroelectric turbine. A traditional wheel directly turns a shaft for mechanical work, while a turbine is a more compact machine often connected to an electrical generator.