No one who has not made the art of singing a special study, can form any idea of the obscure and conflicting views in regard to the transitions of the registers which prevail among singing teachers and artists. Almost every teacher has a peculiar theory of his own in regard to the formation of the voice; every one has his own views, sometimes extremely fanciful, of the formation of tones and of the registers--views to which he tenaciously adheres, summarily rejecting all others. Almost as at the building of the tower of Babel, one teacher scarcely understands any longer what another means, and instead of harmonious endeavors to improve the art, teachers of singing are commonly found disputing among themselves. To bring light and order into such a chaos can only be accomplished by the most thorough scientific study, and even then it is an undertaking of the greatest difficulty. Custom stands in the way as an antagonist, and there must be a conflict with long-cherished and wide-spread errors and prejudices. It lies also in the nature of the case that teachers of singing are the most determined opponents to be encountered. It is very hard for this class, and it demands of them no common self-denial to acknowledge and renounce as errors what they have taught for years and held to be truths. Those teachers, however, who have made the necessary sacrifice, have been compensated with the richest success; and such, we trust, will in all cases be the result, and so the path be broken for the true and the natural. It will be perhaps comparatively easy to advance the art of singing in America; for, as Humboldt says, not entirely without truth, the Germans require for every improvement two centuries--one to find out the need of it, and another to make it. [2] It must be remarked that the diagrams here given are copies of _reflected_ images, and therefore the upper side of the representation shows the front of the larynx, and the lower the farther side of the larynx. [3] In recent works on laryngoscopy they are often described as continuations or parts of one of the principal muscles of the larynx. [4] In recent French and English works upon laryngoscopy, the cuneiform cartilages are frequently mentioned, and sometimes confounded with the cartilages Wrisbergi.