Boiler construction

Claim 1

IN A FIRE TUBE BOILER THE COMBINATION OF FURNACE AND BOILER ELEMENT, SAID FURNACE HAVING A BURNER TO PROVIDE HEAT MEANS TO SAID BOILER ELEMENT SURMOUNTED ON SAID FURNACE, SAID BOILER ELEMENT COMPRISING A HOUSING HAVING OPPOSITE SIDE WALLS, A FRONT WALL, A REAR WALL, A TOP WALL AND A HORIZONTAL INTERMEDIATE WALL ENCLOSING A WATER OR STEAM CHAMBER, A PLURALITY OF FIRE TUBES BETWEEN SAID FRONT AND REAR WALLS, A FRONT DOOR COVERING THE FRONT ENDS OF SAID FIRE TUBES, AND A REAR DOOR COVERING THE REAR ENDS OF SAID FIRE TUBES, SAID REAR WALL HAVING A PLURALITY OF OPENINGS BELOW SAID WATER OR STEAM CHAMBER, SAID FRONT AND REAR DOOR BEING REMOVABLE FROM SAID BOILER TO PROVIDE ACCESS TO SAID FRONT AND REAR ENDS OF SAID FIRE TUBES, WHEREIN SAID REAR DOOR INCLUDES CONNECTION MEANS BETWEEN SAID BOILER AND A CHIMNEY FLUT DUCT, WHEREIN EACH REAR DOOR COMPRISES A PAIR OF REAR DOOR ELEMENTS, EACH OF SAID REAR DOOR ELEMENTS HAVING A CLAMP MEMBER FOR SECUREMENT AROUND SAID CHIMNEY FLUE DUCT, EACH SAID DOOR ELEMENT COMPRISING A VERTICAL PANEL SPACED APART BY CHAMBER MEANS FROM SAID REAR WALL OF SAID BOILER, A SIDE WALL PARTLY AROUND THE PERIPHERY OF SAID PANEL, A FLANGE ON EACH SIDE WALL OF SAID DOOR ELEMENT, OPENINGS IN SAID FLANGE TO RECEIVE BOLTS FOR SECUREMENT TO SAID REAR WALL OF SAID BOILER, AND SECONDARY FLANGES ON EACH REAR DOOR ELEMENT FOR SECURING SAID REAR DOOR ELEMENTS TOGETHER.