rower end to the thyroid cartilage, and possessing a midrib overhanging and corresponding to the fissure of the glottis. The broader end of the leaf points freely upwards toward the tongue, in which direction the entire cartilage presents a concave, as towards the larynx a convex, outline. In swallowing, the epiglottis falls over the larynx, like a saddle on the back of a horse. In the formation of certain letters a horizontal narrow fissure may be produced by depressing the epiglottis over the vertical false and true vocal chords.

Within the larynx (4, 5), rather above its middle,

in the middle, and forming an aperture which is called the interior or true glottis, and corresponds in direction with the exterior glottis. This aperture is provided with muscles, which enlarge and contract Fig. 5.

it at pleasure, and otherwise modify the form of the larynx. The three cartilages of the larynx supply the most perfect mechanism for stretching or relaxing the chords, and likewise, as it would seem, for deadening some portion of them by pressure of a protuberance on the under side of the epiglottis (in German, Epiglottiswulst). These chords are of different length in children and grown-up people, in man and in woman. Their average length in man is 18 mm. when relaxed, 23 mm. when stretched; in woman, 123 mm. when relaxed, 153 mm. when stretched: thus giving a difference of about one

third between the two sexes, which accounts for the different pitch of male and female voices.1

The tongue, the cavity of the fauces, the lips, teeth, and palate, with its velum pendulum and uvula performing the office of a valve between the throat and nostrils, as well as the cavity of the nostrils themselves, are all concerned in modifying the impulse given to the breath as it issues from the larynx, and in producing the various vowels and

consonants.

After thus taking to pieces the instrument, the tubes and reeds as it were of the human voice, let us now see how that instrument is played by us in speaking or in singing. Familiar and simple as singing or music in general seems to be, it is, if we analyze it, one of the most wonderful phenomena. What we hear when listening to a chorus or a symphony is a commotion of elastic air, of which the wildest sea would give a very inadequate image. The lowest tone which the ear perceives is due to about 30 vibrations in one second, the highest to about 4000. Consider, then, what happens in a Presto when thousands of voices and instruments are simultaneously producing waves of air, each wave crossing the other, not only like the surface waves of the water, but like spherical bodies, and, as it would seem, without any perceptible disturbance;2 consider that each tone is accompanied by secondary tones, that each instrument has its peculiar timbre, due to secondary vibrations; and, lastly, let us remember that all this cross-fire of waves, all this

1 Funke, Lehrbuch der Physiologie, p. 664, from observations made by J. Müller.

2 Weber, Wellenlehre, p. 495.

whirlpool of sound, is moderated by laws which termine what we call harmony, and by certain t ditions or habits which determine what we call mp ody, both these elements being absent in the son of birds,—that all this must be reflected like a n croscopic photograph on the two small organs hearing, and there excite not only perception, perception followed by a new feeling even me mysterious, which we call either pleasure or pai and it will be clear that we are surrounded on & sides by miracles transcending all we are accustome to call miraculous, and yet disclosing to the geni of an Euler or a Newton laws which admit of th most minute mathematical determination. 1

For our own immediate purposes it is importa... to remark that, while it is impossible to sing without at the same time pronouncing a vowel, it is perfectly possible to pronounce a vowel without singing it, Why this is so we shall see at once. If we pro nounce a vowel, what happens? Breath is emitted from the lungs, and some kind of tube is formed by the mouth through which, as through a clarinet, the breath has to pass before it reaches the outer air. If, while the breath passes the chorda vocales, these elastic lamina are inade to vibrate periodically, the number of their vibrations determines the pitch of our voice, but it has nothing to do with its timbre or Vowel. What we call vowels are neither more nor less than the qualities, or colors, or timbres of our voice, and these are determined by the form of the vibrations, which form again is determined by the form of the buccal tubes. This had, to a certain extent, been anticipated by Professor Wheatstone in his

tique1 on Professor Willis's ingenious experiments, at it has now been rendered quite evident by the searches of Professor Helmholtz. It is, of course, ppossible to watch the form of these vibrations by eans of a vibration microscope, but it is possible analyze them by means of resounding tubes, like ose before described, and thus to discover in them hat, as we saw, is homologous with the form of bration, viz. the presence and absence of certain armonics. If a man sings the same note on differat vowels, the harmonics which answer to our reunding tubes vary as they would vary if the same bte was played on the violin, or flute, or some other usical instruments. In order to remove all uncerinty, Professor Helmholtz simply inverted the exeriment. He took a number of tuning-forks, each urnished with a resonance box, by advancing or withdrawing which he could give their primary tones alone various degrees of strength, and extinguish their secondary tones altogether. He tuned them so as to produce a series of tones answering to the harmonics of the deepest tuning-fork. He then made these tuning-forks vibrate simultaneously by means of a galvanic battery; and by combining the harmonics, which he had first discovered in each vowel by means of the sounding tubes, he succeeded in reproducing artificially exactly the same vowels.2

We know now what vowels are made of. They are produced by the form of the vibrations. They vary like the timbre of different instruments, and we in reality change the instruments on which we speak when we change the buccal tubes in order to pro1 London and Westminster Review, Oct. 1837, pp. 34, 37. 2. c. n 198.