Another feature of mouth-breathing is that the nasal passages, being thus comparatively unused, consequently fail to keep themselves clean and clear, and become clogged up and unclean, and are apt to contract local diseases. Like abandoned roads that soon become filled with weeds and rubbish, unused nostrils become filled with impurities and foul matter.

One who habitually breathes through the nostrils is not likely to be troubled with clogged or stuffy nostrils, but for the benefit of those who have been more or less addicted to the unnatural mouth-breathing, and who wish to acquire the natural and rational method, it may perhaps be well to add a few words regarding the way to keep their nostrils clean and free from impurities.

A favorite Oriental method is to snuff a little water up the nostrils allowing it to run down the passage into the throat, from thence it may be ejected through the mouth. Some Hindu yogis immerse the face in a bowl of water, and by a sort of suction draw in quite a quantity of water, but this latter method requires considerable practice, and the first mentioned method is equally efficacious, and much more easily performed.

Another good plan is to open the window and breathe freely, closing one nostril with the finger or thumb, sniffing up the air through the open nostril. Then repeat the process on the other nostril. Repeat several times, changing nostrils. This method will usually clear the nostrils of obstructions.

In case the trouble is caused by catarrh it is well to apply a little vaseline or camphor ice or similar preparation. Or sniff up a little witch-hazel extract once in a while, and you will notice a marked improvement. A little care and attention will result in the nostrils becoming clean and remaining so.

We have given considerable space to this subject of nostril-breathing, not only because of its great importance in its reference to health, but because nostril-breathing is a prerequisite to the practice of the breathing exercises to be given later in this book, and because nostril-breathing is one of the basic principles underlying the Yogi Science of Breath.

We urge upon the student the necessity of acquiring this method of breathing if he has it not, and caution him against dismissing this phase of the subject as unimportant.

CHAPTER VII.

FOUR METHODS OF RESPIRATION.

In the consideration of the question of respiration, we must begin by considering the mechanical arrangements whereby the respiratory movements are effected. The mechanics of respiration manifest through (1) the elastic movements of the lungs, and (2) the activities of the sides and bottom of the thoracic cavity in which the lungs are contained. The thorax is that portion of the trunk between the neck and the abdomen, the cavity of which (known as the thoracic cavity) is occupied mainly by the lungs and heart. It is bounded by the spinal column, the ribs with their cartilages, the breastbone, and below by the diaphragm. It is generally spoken of as "the chest." It has been compared to a completely shut, conical box, the small end of which Is turned upward, the back of the box being formed by the spinal column, the front by the breastbone and the sides by the ribs.