The foundation ring. It is the rectangular device with the arrow chalked on it and pictured here upside-down.  Its function is to connect the inner and outer firebox at the base and act as a mounting for the ashpan.
The foundation ring. It is the rectangular device with the arrow chalked on it and pictured here upside-down. Its function is to connect the inner and outer firebox at the base and act as a mounting for the ashpan.
Credit: Dick Bellchambers, 5 May 2005