The tone once launched, one must think how it may be properly sustained, and this is where the art of breathing is most concerned. The lungs, in the first place, should be thoroughly filled. A tone begun with only half filled lungs loses half its authority and is very apt to be false in pitch. To take a full breath properly, the chest must be raised
at the same moment the abdomen sinks in. Then with the gradual expulsion of the breath a contrary movement takes place. The diaphragm and elastic tissue surrounding and containing the stomach and vital organs and the muscles surrounding, by practice acquire great strength and assist considerably in this process of respiration and are vital factors in the matter of controlling the supply which supports the tone. The diaphragm is really like a pair of bellows and serves exactly the same purpose. It is this ability to take in an adequate supply of breath and to retain it until required that makes or, by contrary, mars all singing. A singer with a perfect sense of pitch and all the good intentions possible will often sing off the key and bring forth a tone with no vitality to it, distressing to hear, simply for lack of breath control.
This art of respiration once acquired, the student has gone a considerable step on the road to Parnassus. To practice deep breathing effectively it is an excellent plan to breathe through the nose, which aids in keeping the confined breath from escaping too soon.
The nose also warms and filters the air, making it much more agreeable to the lungs than if taken directly through the mouth. In the practice of slow breathing make sure that the lungs are as nearly emptied as possible on the expulsion of the breath before beginning a new inspiration, as this gives extra impetus to the fresh supply of air and strengthens all the breathing muscles.
If this is not done, moreover, the effect is like two people trying to get in and out of the same narrow door at the same time.