Now we come to the "Registers" of the voice. I have defined a register as "a series of tones produced by the same mechanism." The five registers of which the human voice, taken as a whole, consists, are carefully described, and the means by which they are formed minutely explained in a former part of this book. These registers, nevertheless, continue to be a stumbling-stone to many, and the fact of the existence in the throat of different actions for the production of different series of tones has led some teachers into the deplorable mistake of developing and exaggerating them, instead of, on the contrary, smoothing them over and equalizing them. The result is that we often hear singers who seem to have two or three different _voices_. They are growling in the one, moaning in the second, and shrieking in the third; while it should have been their aim so to blend and to unite the registers as to make it difficult even for a practised ear to distinguish the one from the other. Such singing is outrageous, and I protest against the opinion expressed in some quarters that it is the natural outcome of the teachings of the laryngoscope. In developing and strengthening the registers I base my first exercises upon the fact that the "Vowel Scale" goes from low to high in this order; _oo_, _oh_, _ah_, _ai_, _ee_, so that consequently the highest tones will be produced most readily when singing the vowels in the order just given. [Illustration: musical notation _o_ _ah_ _ai_ _ee_ _ai_ _ah_ _o_ _oo_ _o_ _ah_ _ai_ _ah_ _o_ _oo_ Sing this exercise quite softly, strike each tone clearly and distinctly, and take a _slight_ inspiration after every tone. Be careful to take a full inflation only at the beginning, and afterwards to inhale _less_ air than has been consumed in every preceding tone, or you will after a while overcrowd the lungs, and experience a sensation of being choked. This is a thing to be avoided in any case; but under present circumstances it should be remembered that the short inspirations are not taken for the purpose of re-filling the lungs, but simply to compel the "opening and closing muscles" to do their work. By so doing we give them six times more exercise than by breathing only once at the beginning; and, what is more important still with regard to our immediate object, we greatly facilitate the task of the vocal ligaments to arrange themselves in different ways according to the registers they are to produce.