Down"com`er (?), n.
A pipe to conduct something downwards; specif.:
(a) (Iron Manuf.)
A pipe for leading the hot gases from the top of a blast furnace downward to the regenerators, boilers, etc.
(b) (Steam Engin.)
In some water-tube boilers, a tube larger in diameter than the water tubes to conduct the water from each top drum to a bottom drum, thus completing the circulation.
© Webster 1913