Tymp
An opening in the masonry of a blast-furnace hearth, across the top of which is laid either a block of refractory stone, or a hollow iron block, through which a current of water is kept constantly flowing to prevent it from melting. The dam-plate stands a little below and supports the dam-stone, which forms the front of the fore-hearth. The slag flows over the tymp, while the reduced iron collects in the hearth below. See CAST IRON.