I am not going to recommend the consumptive, nor any person, well or ill, to do all or much of his breathing through the mouth; on the contrary, I agree that the nostrils were designed to warm and filter the air, and that in general this is necessary. But there are times when the atmosphere does not require to be _filtered_ and when it had better not be _warmed_; and I wish to do away with all fear of danger from casual or occasional open-mouth breathing, especially in the _open air_, and in winter, or at any season when there is freedom from dust, and regardless of the weather, and the time of day or night. For “sore” or irritated throat and bronchi, or oppressed lungs, I have found persistent open-mouth breathing of pure cold air curative in its tendency; and have myself, upon occasion, gone out on a winter’s night, to walk and breathe in this manner by the hour. Consumptives are often subject to attacks of dyspnœa (difficult breathing), but rarely, if ever, do they come on out of doors; it is rather, when, having been vouchsafed a little pure respiratory food, the lungs are again forced to respire the hot, poisoned, make-believe air of the home, that the congestion takes place. And this may be set down as the only danger in the premises, viz.: the return from the fresh, pure and bracing atmosphere without, to the over-heated and under-ventilated living-rooms. The remedy, then, for an attack under such circumstances would be found in throwing open the doors and windows——keeping well wrapped or warm in bed——rather than in sealing the crevices and piling on fuel. Even _pneumonia_, most dreaded of “diseases,” in which the lungs are congested to engorgement, is now being successfully treated on this principle——the persistent open-mouth breathing of out-door air, if in the winter, or the same, drawn through an ice-packed refrigerator——(scrupulously clean and profusely ventilated), if the weather be warm; the patient, meanwhile, being _warm_ in bed, though never sweltered with wraps [the aim being to balance the temperature, by cooling the head, heating the feet, and exposing and sponging the feverish surface, as may be indicated], and supplied with a proper face-piece to which is attached a flexible tube, through which the cold air is passed direct to the lungs; this manner of breathing to be _constant_ and _uninterrupted_, hour after hour, and throughout the night, if necessary (_never_ remittent), until the temperature of the patient, as indicated by the thermometer placed under the arm, is reduced to about the normal point (98.2° F.), and the pressure at the lungs relieved. The philosophy of this treatment is as evident as is that of the playing of an engine upon the hottest part of a fire. A WORD ABOUT THE BED.