Leonardo da Vinci designed a roasting jack to turn a spit automatically while meat roasted.
A roasting jack uses mechanical power to rotate a spit, allowing food to cook more evenly over a fire. Leonardo’s design employed a system of gears and a propeller-like component driven by rising hot air from the flames. As the heated air moved upward, it could turn the mechanism and transfer motion to the spit.
The device illustrates how Leonardo applied mechanical principles to ordinary household work. It also shows his interest in using natural forces, including heat and airflow, as sources of motion.
A roasting jack is not an oven and does not cook by enclosing food in controlled hot air. It mainly automates rotation. The design is also distinct from later motorized rotisseries, which use electric motors rather than heat-driven mechanical power.