Convinced that only by the way of scientific investigation the desired end could be reached, I sought the counsel of Prof. _Helmholtz_, in Heidelberg. This distinguished man was then engaged in a scientific inquiry into the natural laws lying at the basis of musical sounds. Prof. Helmholtz permitted me to take part in his investigations, and at his kind suggestion I attempted by myself, by means of the laryngoscope, to observe the physiological processes that go on in the larynx during the production of different tones. My special thanks are due to him that now, with a more thorough knowledge of the human voice, I can give instruction in singing without the fear of doing any injury. My thanks are due in a like manner to Prof. _du Bois-Reymond_, in Berlin, who, at a later period, also gave me his friendly help in my studies. In 1861 I published a part of my investigations in Germany, where they found acknowledgment and favor. That little work is contained in the following pages, together with some account of the discoveries of Professor _Helmholtz_ relating to the human voice, and of their practical application to the education of the voice in singing. The practical sense of the American people enables them, above all others, to appreciate the worth of every discovery and of every advance. And therefore it is my earnest hope that the publication of these investigations in this country may help to elevate and improve the Art of Singing. THE VOICE IN SINGING I VOCAL MUSIC ITS RISE, DEVELOPMENT AND DECLINE It is a matter of complaint among all persons of good taste, who take an intelligent interest in art, and especially in music, that fine singers are becoming more and more rare, while formerly there appears never to have been any lack of men and women eminent in this art. The complaint seems not altogether without reason, when we revert to that rich summer-time of song, not yet lying very far behind us, in the last half of the last century, and compare it with the present. The retrospect shows us plainly that the art of singing has descended from its former high estate, and is now in a condition of decline. When we consider what is told us in the historical works of _Forkel_, _Burney_, _Kiesewetter_, _Brendel_ and others, and compare it with our present poverty in good voices and skilful artists, we are struck with the multitude of fine voices then heard, with their remarkable fulness of tone, as well as with the considerable number of singers--male and female--appearing at the same time.