You have now learned, first, how to breathe correctly, second, how to pass from one vowel to another and from one syllable to another, the first lesson in legato singing, and how to pass from one note to another up and down short scales.
Legato means “BOUND TOGETHER”; it does not mean slurring or confusing one vowel sound with another. Each note must be perfectly sounded, each vowel perfectly formed. The transition from one to the other is exact and quick, but never aspirated nor with a gap between notes or vowels.
Be sure the lips are free and allowed to act naturally, probably more exaggerated in their action than in ordinary speech.
Avoid being too analytical, and do not pay over-attention to any one part of the breathing muscles.
Try preparing for a great exclamation of joy, and you will see how quickly and easily the whole body acts to take the breath necessary for the exclamation. You will also see, by placing one hand on the upper abdomen, and the other on the sides of the ribs, just what these parts do when you exclaim. They do the same when you sing. The upper abdomen pulls in and the ribs hold outwards. The chest should never fall on attack of the tone, but do not hold it up locally.
Here another caution is necessary. Do not try to control any breathing organ or vocal organ locally. Even the lips are guided by correct pronunciation more than by local control.
Do not open the mouth too widely. It will ruin good diction and destroy resonance. It will also often cause imperfect intonation, the worst of all bad faults.
Also do not sing with the mouth too closed. It will make the voice gloomy and dull, and the vowels will be very poor in character.
Open the mouth about the width of a thumb. This is an old rule. I think that the mouth never opens more than one inch in ordinary good singing, except on the higher notes, when it will open a little more. Nature will guide you in this, as will the vowel sound and the volume desired.
Now sing exercises 1 to 5 again, and you will greatly improve your singing. Also practice Nos. 6, 8, 9, 10. Use the syllables as given already, and also the vowels given in the exercises.
You may still continue to use the arms.
Witherspoon, Herbert. Thirty-Six Lessons in Singing for Teacher and Student. Meissner Institute of Music. Chicago. 1930.