“Suppose, for example, a thousand persons are seated in a room forty feet in width, sixty in length, and fifteen in height; how long a time would elapse before the air of such a room would become unfit for further respiration? Remembering that each person spoils one foot of air every second, it is clear that one thousand cubic feet of air will be contaminated for every second that the room is occupied. To ascertain the number of seconds which would elapse before the entire air contained in the room will be contaminated, so that it is unfit for further breathing, we have only to divide the cubic contents of the room by one thousand. Multiplying, we have 60 × 40 × 15 equals 36,000, the number of cubic feet. This, divided by one thousand, gives thirty-six as the number of seconds. Thus it appears that with closed doors and windows breath poisoning of the audience would begin at the end of thirty-six seconds, or less than one minute. The condition of the air in such a room at the end of an hour cannot be adequately pictured in words, and yet hundreds of audiences are daily subjected to just such inhumane treatment through the ignorance or stupidity of architects, or the carelessness of janitors, or the criminal negligence of both.” TUBERCULOSIS POINTS THE MORAL No circumstance has been more successful in impressing the great importance of fresh air and adequate ventilation upon the public mind than the success which has attended the open air cure for consumption. This is a mode of treatment of comparatively recent adoption in America, but it is by this time generally recognized as really the only possible cure for tuberculosis. The mortality from this disease is greater than any except pneumonia; another disease that proper breathing habits will do much to avert. In America one person in every nine dies of tuberculosis; and of the deaths which occur between the ages of fifteen and thirty-five, one-third are due to the great white plague. We give these figures on the authority of Professor Irving Fisher of Yale, who is Secretary of the New Haven AntiTuberculosis Association. His interest in this disease is that of one who has had it, and who has cured it by the open air treatment. Of the authors of this book, one has had an experience similar to Professor Fisher. There is nothing academic about this insistence on the need of fresh air and proper breathing habits; literally, and in the fullest degree, it is a question of life and death whether you shall breathe properly, and have good air to breathe, or whether you shall not. HOW BREATHING AIDS THE BATTLE OF THE BLOOD