Bŭt'ter-fly-vălve, n.
n. (Mech.) A species of double clock-valve, consisting of two semicircular clappers or wings hinged to a cross-rib cast in the pump-bucket, and so named from its resemblance to a butterfly when open.
n. (Mech.) A species of double clock-valve, consisting of two semicircular clappers or wings hinged to a cross-rib cast in the pump-bucket, and so named from its resemblance to a butterfly when open.