Smoke jacks were only cheap, however, if fuel use was not taken into account. To keep the vane turning in the smoke, grotesque amounts of wood or coal had to be kept burning in the hearth. In 1800, it was calculated that you could use one-thousandth of the fuel needed to make a smoke jack work to power the spit with a small steam engine instead. Because spit-roasting was so central to British cooking, much intelligence was lavished on inventing improved methods of turning the spit.
