The larynx bears certain resemblances to both stringed and wind instruments, but it is really unique (_sui generis_). The vibrations of the vocal bands are caused solely by the expiratory current of air, which is more or less held back by the cords, owing to their approximation, so that the greater the obstruction the stronger must the blast of air be, other things being equal, and the result increase in pitch. The problem Nature had to solve is very complex. The laryngoscope was invented in 1854 by a teacher of singing, Manuel Garcia, who soon after gave an account of it to the Royal Society of England. The instrument consists essentially of two mirrors, the external, or "head-mirror," which is concave and reflects into the larynx, and the internal, or "mouth-mirror," which reflects the picture outward to the eye. The latter mirror is plane, and set at an angle. The picture may show, under the most favorable circumstances, all the upper parts of the larynx, including the vocal bands, but sometimes, also, the windpipe as far down as its division into the two main bronchial tubes. The difficulties commonly met with in the use of the instrument are a constrained action of the throat and mouth parts of the subject, unnatural breathing, an unruly tongue, etc. The epiglottis may, also, naturally so overhang the glottis that a good view of the vocal cords is impossible. It is difficult to see more than one-half to two-thirds of the length of the vocal bands. The picture seen is that of the parts of the larynx reversed--_i.e._, while right remains right, posterior becomes anterior. The laryngoscope shows that (1) in singing an ascending scale the vocal bands are for a certain time in action (vibration) throughout their whole length; that (2) there may be observed a rather sudden change when the vocal bands are relaxed and shortened, and that this process of shortening goes on, the bands approaching more and more, both behind and in front, till (3) in the highest tones of a soprano of great range there is only a small portion of each vocal cord toward the centre that is not approximated somewhat closely.