(under subclass 349) Devices in which the products of
combustion pass out of the firebox at the rear and return over the firebox between the water tubes.
SEE OR SEARCH THIS CLASS, SUBCLASS:
346, for such devices in which the water tubes are located beyond the bridge wall and above the firebox and arranged so that the products of combustion pass over the bridge wall and upwardly through a separate passage to the front of the boiler before they are discharged.
