Leonardo da Vinci designed an automatic spit that turned meat while it roasted.
The mechanism used a propeller or fan placed in a chimney. Rising hot air turned the propeller, and gears transmitted that motion to the roasting spit. As the fire became hotter, the stronger upward airflow could make the spit rotate faster, helping automate a task that normally required a person to turn it by hand.
Leonardo was interested in kitchen machinery as well as weapons, bridges, and flying devices. His design shows how he applied observations about hot air and mechanical transmission to domestic work. It also demonstrates that an invention need not be monumental to be technically significant.
The device is often called an automatic spit or self-turning spit. It is not the same as a modern motorized rotisserie, because Leonardo's design relied on thermal convection rather than an electric motor. The exact operation of reconstructed versions depends on the details of the gears and the strength of the rising air.