A foot stove consists of a wooden box which is open on one side, with holes at the top. In it, a bowl of pottery or metal with burning charcoal

Charcoal

Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...

was placed. The feet were positioned on top of the stove to become warm. By putting a blanket or clothing on the legs the heat could be isolated and the lower legs were heated.

Foot stoves were used in several European countries.