The mistake usually made is to lift the chest with each inspiration. This only raises it, it does not expand it. The proper way is to breathe from the abdomen and lower part of the chest wall. When this is done every part of the lung is filled with air, and this has the great advantage of preventing the air inside the lung spaces from stagnating in any one part, an occurrence which is always prone to lead to the onset of congestion or disease.
It does another good turn too, for it inculcates the habit of deep, full breathing. Those who practise for a few minutes each day will soon find themselves expanding their lungs habitually, even when they are not thinking about it.
Yet even if windows and doors are kept open, something more is requisite. For unless a house is scrupulously clean and the rooms regularly turned out, it cannot be healthy. If a piece of machinery is left untouched for some months it will never be as good as it was before. The grease has become foul, whilst dust and dirt have accumulated, and these insidious elements have combined to destroy the quality of the metal. That means that some time or other some bar or joint or nut will crack, and once that has happened the mischief rarely stops there, but goes on to the weakening of other parts and the deterioration of the whole machine.
And when human beings live in houses that are not fresh and wholesome they are constantly inhaling dust and fusty smells, which act as a slow, subtle poison and lower the vitality of the various tissues of the body. It is so gradual that they may not notice it, until at last something gives way, and after that the downward tendency becomes comparatively rapid. When the cataclysm occurs, they date it from the day when the first crack, if we may call it so, appeared. Rather should they look back to the long years spent in an unhealthy atmosphere within their own homes.
There is no fault, however apparently trivial it may seem, in matters of hygiene which does not add its quota towards the final breakdown of the human machinery. The faulty, leaking gaspipe which causes oft-repeated morning headaches; the choked-up scullery sink, with its abominable mixture of soap, grease and vegetable washings; the defective drain and pipes; each and all do their evil part in undermining the constitution and rendering it more prone to the onset of disease.