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Between these two extreme functions of the palate and breath, one stream of breath gives some of its force to the other; and when equally divided they form the medium range of all classes of voices (Plate B).

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The singer must always have in his mind's eye a picture of this divided stream of breath.

As I have already said, in the lowest tones of all voices the main stream of breath is projected against the palate; the pillars of the fauces, being stretched to their fullest extent, and drawn back to the wall of the throat, allow almost no breath to reach the head cavities.

I say almost none, for, as a matter of fact, a branch stream of breath, however small, must be forced back, behind and above the pillars, first into the nose, later into the forehead and the cavities of the head. This forms the overtones (head tones) which must vibrate with all tones, even the lowest. These overtones lead over from the purest chest tones, slowly, with a constantly changing mixture of both kinds of resonance, first to the high tones of bass and baritone, the low tones of tenor, the middle tones of alto and soprano, finally, to the purest head tones, the highest tones of the tenor-falsetto or soprano. ([See the plates].)

The extremely delicate gradation of the scale of increase of the resonance of the head cavities in ascending passages, and of increase of palatal resonance in descending, depends upon the skill to make the palate act elastically, and to let the breath, under control of the abdominal and chest pressure, flow uninterruptedly in a gentle stream into the resonating chambers. Through the previous preparation of the larynx and tongue, it must reach its resonating surfaces as though passing through a cylinder, and must circulate in the form previously prepared for it, proper for each tone and vowel sound. This form surrounds it gently but firmly. The supply of air remains continuously the same, rather increasing than diminishing, notwithstanding the fact that the quantity which the abdominal pressure has furnished the vocal cords from the supply chamber is a very small one. That it may not hinder further progression, the form must remain elastic and sensitive to the most delicate modification of the vowel sound. If the tone is to have life, it must always be able to conform to any vowel sound. The least displacement of the form or interruption of the breath breaks up the whirling currents and vibrations, and consequently affects the tone, its vibrancy, its strength, and its duration.

In singing a continuous passage upward, the form becomes higher and more pliant; the most pliable place on the palate is drawn upward. ([See Plate A].)

When I sing a single tone I can give it much more power, much more palatal or nasal resonance, than I could give in a series of ascending tones. In a musical figure I must attack the lowest note in such a way that I can easily reach the highest. I must, therefore, give it much more head tone than the single tone requires. (Very important.) When advancing farther, I have the feeling on the palate, above and behind the nose, toward the cavities of the head, of a strong but very elastic rubber ball, which I fill like a balloon with my breath streaming up far back of it. And this filling keeps on in even measure. That is, the branch stream of the breath, which flows into the head cavities, must be free to flow very strongly without hindrance. ([See Plate B].)