bell mouth

Old as an unpaid bill and worn bell-mouth it is, and nobody can fire with it.

Vestiges of a bell-mouth can be seen while traveling on the local tracks south of Canal Street.

The four nozzles of this then exhaust into the fourth stage, the classic chimney (U.S.: stack) bell-mouth.

It was Chapelon's theory that such a multi-stage mixing and suction arrangement would be more efficient than the single stage arrangement hitherto popular in steam locomotive draughting, in which an exhaust nozzle simply is fired up the middle of the stack bell-mouth.