Gaseous fuel burners

Claim 1

A GASEOUS FUEL BURNER HAVING A MIXING HEAD COMPRISING IN COMBINATION AN ENTRANCE PORTION HAVING AT LEAST TWO PARALLEL WALLS, AND ENTRANCE OPEN TO THE AMBIENT AIR AND A CROSS SECTIONAL AREA TAKEN TRANSVERSELY WITH RESPECT TO THE LENGTH OF THE BURNER MIXING HEAD WHICH DECREASES FROM A MAXIMUM AT SAID ENTRANCE TO A MINIMUM WITHIN A JUNCTION BETWEEN SAID ENTRANCE PORTION AND AN INTERMEDIATE PORTION HAVING A SUBSTANTIALLY STRAIGHT LONGITUDINAL AXIS INCLINED UPWARDLY WITH RESPECT TO THE PARALLEL WALLS OF SAID ENTRANCE PORTION, SAID INTERMEDIATE PORTION COMPRISING SPACED WALLS ONE OF WHICH IS BULGED OUTWARDLY, AN EXIT PORTION JOINED TO SAID INTERMEDIATE PORTION AND HAVING PARALLEL WALLS LYING IN PLANES PARALLEL TO BUT SPACED FROM THE PLANES IN WHICH THE PARALLEL WALLS OF THE ENTRANCE PORTION LIE, THE CROSS SECTIONAL AREA OF THE EXIT PORTION TAKEN TRANSVERSELY OF THE LENGTH OF THE MIXING HEAD INCREASING FROM A MINIMUM AT THE JUNCTION BETWEEN THE EXIT AND INTERMEDIATE PORTIONS TO A MAXIMUM AT A POINT ADJACENT THE EXIT FROM THE EXIT PORTION, THE WIDTH OF SAID INTERMEDIATE PORTION IN A DIRECTION PERPENDICULAR TO SAID PARALLEL WALLS BEING AT LEAST AS GREAT AS THAT OF SAID EXIT PORTION, WHILE ITS AVERAGE CROSS-SECTION AREA TAKEN TRANSVERSELY OF THE LENGTH OF THE MIXING HEAD IS LESS THAN THAT OF EITHER SAID ENTRANCE OR EXIT PORTION, SLOTS IN SAID PARALLEL WALLS OF SAID ENTRANCE PORTION, A GAS SUPPLY PIPE POSITIONED IN SAID SLOTS, AND, IN SAID GAS SUPPLY PIPE AND ORIFICE LOCATED WITHIN THE CONFINES OF SAID ENTRANCE.