What machine did Leonardo da Vinci design to produce continuous rotary motion from a waterwheel?

Leonardo da Vinci designed water-powered mills that used a waterwheel to produce continuous rotary motion.

In his notebooks, Leonardo examined waterwheels, gears, shafts, pumps, and other components that transferred the energy of moving water to useful work. A waterwheel could turn machinery for milling grain, lifting water, or operating other mechanical systems. His drawings often focus on how individual parts should be arranged and supported.

Waterwheels were ancient technology rather than Leonardo’s invention. Their use expanded widely in medieval and Renaissance Europe, and Leonardo’s contribution was analytical: he studied their operation, efficiency, and mechanical applications in unusual detail. Some drawings show ambitious compound mechanisms, but they should not be mistaken for evidence that Leonardo built an industrial power station.