Steam and hot water boiler

Claim 1

A BOILER COMPRISING: (A) A GENERALLY HORIZONTALLY ELONGATED VESSEL ADAPTED TO CONTAIN LIQUID TO BE HEATED AND HAVING FRONT AND REAR ENDS; (B) MEANS IN THE FRONT END PORTION OF THE VESSEL DEFINING A COMBUSTION CHAMBER HAVING OUTER AND INNER ENDS, THE MEANS DEFINING THE INNER END OF THE COMBUSTION CHAMBER COMPRISING A TUBE SHEET SPACED FROM THE FRONT AND REAR ENDS OF THE VESSEL; (C) MEANS DEFINING THE FLUE GAS RECEIVING CHAMBER ADJACENT TO THE REAR OF THE VESSEL, SAID LAST NAMED MEANS COMPRISING A SECOND TUBE SHEET, NEAR THE REAR OF THE VESSEL; (D) A PLURALITY OF SUBSTANTIALLY PARALLEL FIRE TUBES EXTENDING BETWEEN THE TUBE SHEETS AND PROVIDING PASSAGES THROUGH WHICH COMBUSTION GASES CAN FLOW FROM THE COMBUSTION CHAMBER TO THE FLUE GAS RECEIVING CHAMBER IN HEAT EXCHANGE RELATION WITH LIQUID IN THE VESSEL, SAID FIRE TUBES BEING INCLINED SO THAT ONE END OF EACH IS HIGHER THAN ITS OTHER END; (E) A PLURALITY OF WATER TUBES, SAID WATER TUBES BEING DISPOSED IN THE FIRE TUBES WITH THEIR AXES PARALLEL TO THOSE OF THE FIRE TUBES AND THEIR WALLS RADIALLY SPACED FROM THOSE OF THE FIRE TUBES SO THAT COMBUSTION GASES FLOWING THROUGH THE FIRE TUBES MOVE IN HEAT EXCHANGE RELATION TO THE WATER TUBES, EACH OF SAID WATER TUBES (1) HAVING A LENGTH SUBSTANTIALLY EQUAL TO THAT OF THE FIRE TUBE IN WHICH IT IS DISPOSED, AND (2) HAVING ITS OPPOSITE END CLOSED; (F) A PAIR OF TUBULAR LATERALLY EXTENDING BRIDGING MEMBERS FOR EACH WATER TUBE, ONE NEAR EACH END THEREOF, EACH COMMUNICTION THE INTERIOR OF ITS WATER TUBE WITH THE EXTERIOR OF THE FIRE TUBE IN WHICH THE WATER TUBE IS DISPOSED, TO PROVIDE FOR THERMAL CIRCULATION OF LIQUID FROM THE INTERIOR OF THE VESSEL UPWARDLY ALONG THE INCLINED WATER TUBES IN HEAT EXCHANGE RELATION WITH COMBUSTION GASES FLOWING THROUGH THE FIRES TUBES; AND (G) EXTENDED SURFACE IN THE SPACE BETWEEN THE FIRE AND WATER TUBES HAVING INTIMATE CONTACT WITH AT LEAST ONE OF SAID TUBES.