hence the human voice must ever be incomparably superior, as a musical instrument, to all human inventions. A good reader, a good speaker, or a good singer never fails to attract the multitudes.

The lower vocal cords are chiefly instrumental in the production of sound. If the upper cords are removed, voice continues, but is rendered feeble; if the lower cords are destroyed, voice is entirely lost.

The tones of voice depend on the varying tension of the vocal cords. In producing tones, the ligaments of opposite sides are brought into approaching parallelism with each other, by the approximation of the points of the arytenoid cartilages; in the intervals they are again separated, and the opening between them, termed rima glottidis, assumes the form of the letter V, as represented in Fig. 8.

Fig. 8 exhibits the vocal ligaments as seen superiorly. G, E, H. Thyroid cartilage. N, F. Arytenoid cartilages. S, V, S, V. Vocal cords or ligaments. N, X. Crico-arytenoideus lateralis. V, k, f. Right thyro-arytenoideus. N, 1, N, 1. Crico-arytenoidei postici. B, B. Cricoarytenoid ligament.

The muscles which stretch or relax the vocal ligaments, are alone directly concerned in the voice; the muscles which open and close the glottis, regulate the amount of the air inspired and expired.

The pitch of the tones is regulated by the tension of the vocal cords; its volume or intensity depends on the capacity of the lungs, length of the trachea, flexibility of

the vocal cords, and the force with which the air is expelled from the lungs. The character of the voice is dependent on the confirmation of the pharynx, mouth, and nasal cavities. In the male the larynx is more prominent and the vocal cords are longer than in the female, in the proportion of three to two, which renders the voice in most cases an octave lower.

The free play of the diaphragm is an important factor in the volume of voice. To understand this matter fully it must be recollected that the movements of the respira tory apparatus are partly voluntary, for the purposes of being subservient to voice and speech, and partly invol untary, for the purposes of aerating the blood. The lungs themselves are entirely passive in respiration. When the walls of the chest are drawn asunder, and the thorax dilated by the action of the respiratory muscles, the atmospheric air rushes into the air-cells, distending them in proportion to the dilatation of the thorax, and keeping the surface of the lungs accurately in contact with the walls of the chest in all their movements. But if air be admitted into the cavity of the pleura, outside of the lungs, as by a penetrating wound, the lungs cannot be fully distended by inspiration, but will remain partially collapsed, although the thorax expands, for the reason that the pressure from without balances that within the air-cells. Fig. 9 illustrates the action of the diaphragm in respiration.

The diaphragm, by extending the ribs and pressing down the abdominal viscera, is the principal agent in inspiration. In a deep inspiration, the little muscles between the ribs (intercostals) assist in the expansion of the chest by spreading the ribs, aided also to some extent by the muscles of the thorax generally. Expiration,

Fig 9.

as already stated, is mainly accomplished by the contraction of the abdominal muscles, which, by drawing down the ribs and compressing the viscera up against the relaxed diaphragm, diminish the cavity of the thorax from above.

Says Marshall (Outlines of Physiology): "The human vocal apparatus is analogous to a wind instrument with a double membranous tongue, the bronchi and trachea representing the windtube, the vocal cords the double

Fig. 9 is a side view of the chest and abdomen in respiration. 1. Cavity.of the chest. 2. Cavity of the abdomen. 3. Line of direction for the diaphragm when relaxed in expiration. 4. Line of direction when contracted in inspiration. 5, 6. Position of the front walls of the chest and abdomen in inspiration. 7, 8. Their position in expiration.

3

2

8

6

ACTION OF THE DIAPHRAGM.

membranous tongue, and the parts above the glottis the attached tube. For the production of vocal sounds, even the feeblest, more air must pass through the glottis than in respiration; and this current of air must undergo penidic interruptions in its passage through that fissure. The vocal cords, moreover, are made more or less tense, and are approximated so as to be parallel to each other, and the fissure of the glottis is converted into a fine chinklike opening. The escape of the air propelled upward through the trachea being thus retarded, the margins of the vocal cords are forced upward, and slightly separated from each other; the elasticity of the cords is now called into play, so that they counteract the force of the impulse

communicated to them, and, by a downward recoiling movement, again narrow the glottis. In this manner, the oscillations into which the vocal cords are thrown by the escape of the air driven from the trachea, or wind-tube, are communicated to the less tense air above the glottis, and throw this into vibrations. By means of the laryngeal ventricles, or sacs, placed above the vocal cords, these latter are kept free, so that their vibrations are easily accomplished. It has also been supposed by some, that the superior vocal cords maintain the strength and quality of the sounds, by entering into simultaneous and synchronous vibrations. This is contrary to Señor Garcia's observations with the laryngoscope; but he found that, in elevation of the pitch of the voice, whether natural or falsetto, the superior vocal cords approached each other, so as to narrow the part of the vocal tube above the glottis." The ordinary range of the human voice, from the lowest male to the highest female voice, is nearly 4 octaves.

Fig. 10. E.

Fig. 11. C.

Fig. 12. F.

Fig. 13. A.

The lowest note, E (Fig. 10), is caused by 80 vibrations per second, and the highest note, C (Fig. 11), by 1,024 vibrations per second. But in exceptional cases, the range may be nearly 5 octaves, the lowest note, F (Fig. 12), being caused by 42, and the highest note, A (Fig. 13), by 1,708 vibrations.

In ordinary speech, the range of voice is usually about half an octave; but in singing, the compass of the voice in the same individual generally extends over 2 octaves. In rare cases it has extended over 3 octaves. It

has been calculated that no less than 240 different states of tension of the vocal cords are producible at will, each degree of tension modifying the sound of the note in singing, or of the tone in speaking, and all this in a voice of ordinary range. Celebrated singers can produce a still greater number of intermediate tones. "Madame Mara," says Marshall, "could effect as many as 2,000 changes.”

The bass and tenor varieties of voice are characteristic of the male, and the contralto and the soprano, otherwise known as second treble and first treble, of the female sex. The subdivision of voice called baritone, is intermediate between the tenor and bass, and the mezzo-soprano is intermediate between the soprano and contralto. The lowest note of the contralto is about an octave higher than the lowest note of the bass voice; and the highest soprano about an octave higher than the highest tenor.

The personal quality or peculiar tone of voice is due to the general confirmation of the air-passages; but in both sexes, more especially in the male, two series of notes can be produced, which have been distinguished into the true or chest notes, and the falsetto or head notes. The chest notes are called those of the natural voice, and are fuller, stronger, and more resonant, and are the lower notes of the voice; the falsetto notes are softer, less clear, and have a humming sound resembling the harmonic notes of strings. The middle notes of the scale can be produced by either the chest or the head voice. Some persons can speak or sing with either voice so well marked as to seem to be endowed with two distinct voices. Various theories have been advanced to account for the falsetto voice; but the observations of Garcia seem to prove that, during the production of the falsetto notes, the glottis is more elongated and widened, and that only the edges of the