"It is estimated," says a recent clever writer (H. T. Finck), "that there are from seventy-five to one hundred cubic inches of air which always remain in a man's lungs. About an equal amount of 'supplemental ' air remains after an ordinary expiration; and only twenty to thirty inches of 'tidal air' as Huxley calls it, passes in and out."
You have seen in a river-bend, where the deep water is stagnant, a floating log lie stationary for weeks and months. It would lie there, in the green scum, if let alone, till the freshet came in the spring. There is a lot of that kind of still air in the lungs, waiting for a freshet—which some placid people never experience (these are the nice, pallid, delicate dyspeptics).
The unused and undisturbed air in the lungs, if originally breathed in from close and exhausted rooms, can become as foul as the stagnant river-pool. It must be expelled—and how? By deep-breathing.
"There are few persons," says the author of "Personal Beauty," "whose health and personal appearance would not be improved vastly if they would take several daily meals of fresh air—consisting of twenty to fifty deep inspirations—in a park or some other place where the air is pure and bracing."
Deep-breathing is a mighty means of preserv-
