Falling-doors
Hinged doors attached to the underside of a cupola, which, when the metal has all run out, may be suddenly dropped, permitting the slag and cinders to fall out into the pit below. See CUPOLA.
Twelve hundred entries from the golden age of cast metal — how bells are founded, why brass is not bronze, what a cupola melts and a core withstands — by Simpson Bolland, the trade's great teacher.
Hinged doors attached to the underside of a cupola, which, when the metal has all run out, may be suddenly dropped, permitting the slag and cinders to fall out into the pit below. See CUPOLA.