dominal, and the intercostal muscles, all of which are con cerned in the production of voice! "How wonderful is man! How passing wonder, He that made him such !"

17. The precise manner in which such an infinite variety of tones is produced, is unknown; physiologists explaining the matter according to their respective theories, whether the larynx be a wind or stringed instrument. The glottis doubtless contracts for the production of acute or sharp tones; but how grave ones are produced, admits of doubt, whether it be owing to a lengthening of the trachea, or the relaxation of the vocal chords Perhaps it would be

near the truth to say, that both these circumstances take place, but that the grave notes are chiefly caused by the latter.

18. Ventriloquism consists in making the voice appear to proceed from other persons in various places, either in or out of the room. To do this. with success the performer first directs the attention of the audience to the place from whence he wishes to have his voice appear to proceed; he then changes his voice in such a manner as makes it sound like that of another person, or the noise of the animal he designs to imitate, and in doing so, avoids all the words which have labials, or which require the use of the lips. This modification of voice is supposed to be performed by the muscles of the larynx, and this is known to be the sole organ of all the natural cries.

19. There are generally considered to be two kinds of voice, the natural and acquired. The former is possessed in common with man, by the inferior animals, but the latter is enjoyed by man alone to any extent The natural voice consists in mere cries, and is possessed by the infant as soon as it is born, and also by idiots, and by those who are born dumb. It is seated entirely in the larynx, and does not depend on intellect, or hearing.

20. The acquired voice, on the contrary, is the result of imitation, and enables us to express our ideas in words of

articulate sounds. (In this way the child learns to imitate the sounds which he hears, and if he is deaf, of course he will never learn to speak: children therefore are dumb, because they are deaf. Idiots also are dumb, although they can hear; (intellectual faculties, therefore, are necessary to speech as well as hearing and it is probably owing to a want of intellect that infants do not speak at an earlier age. For the same reason, the ourang outang cannot acquire the faculty of speech. In the acquired voice, the tongue and lips are brought into exercise, but neither of them can be regarded as absolutely essential to the faculty of speech.

21. Whistling is caused by the expired air being broken or divided by the lips, which act the part of the glottis in the production of the voice.) (Whispering consists in the • articulation of the air of expiration, and is wholly performed in the vocal tube; hence the impossibility of singing in a whisper-singing being produced in the glottis. Sighing is produced by the rushing of the air along the air passages and the voice is also concerned in laughing, crying, coughing, sneezing, yawning, and sobbing, modified by the mode of respiration.

22. Singing is a very useful art, and ought to be learned by every person. It not only contributes to our intellectual gratification, but is also of essential benefit to the bodily health. For these reasons, and because it conduces to beget an habitual cheerfulness of mind, it ought to be taught in all schools and academies, and made a part of the daily exercises, as it is in Germany, and in our own infant schools.

Questions.

rynx composed of? scribe its structure?

What is voice? Where is its seat? What is the laWhat is the shape of the thyroid cartilage? DeThe cricoid ?—its structure and situation? De. scribe the arytenoid cartilages? What is the glottis ?-the epiglottis ? What is the thyroid gland?-its use?-the seat of what disease?

What does the whole vocal apparatus comprise? What is essential to the production of voice? What effect has cutting the nerves which go to the larynx? What part of the larynx can be removed without effecting the voice? What are chiefly concerned in the production of voice? Is the larynx a wind or stringed instrument? What does the strength of the voice depend on? What is a change of voice owing to? What is said of the tone of the voice? How many muscles are concerned? How many combinations can they produce? How are acute sounds produced? How grave ones? What is ventriloquism? What is natural voice? What acquired? Why are deaf children dumb? Why are idiots? What is whistling ?-whispering ?—sighing, &c.? What is said of singing?

CHAPTER XXVI.

LOCOMOTION AND ITS ORGANS.

1 MAN is distinguished from the vegetable world, not only by his possessing a nervous system, organs of sense, and voice, but also by the power of locomotion or (moving from place to place. This power connects him with the external world, enlarges his sphere of action and increases his means of acquiring knowledge. It implies that he has a will, and that these motive organs are under the influence of volition ;) else he would be the sport of chance and wander about without a motive.

2. Many of the functions of the body are not under the control of the will; such are digestion, absorption, circulation, respiration, and secretion, which go on as well when we are asleep as when awake. They are possessed, at least some of them, by vegetables as well as animals, and are therefore called organic functions.

3. The agents of locomotion are the bones and muscles; but they would be useless for motion were they not supplied with nerves of voluntary motion, and thus brought under the influence of the will. The bones are tied together by means of strong fibrous ligaments or cords, allowing the joints great freedom and extent of motion, as we see in the shoulder and hip joints.

4. We then have the bones, which act as levers; the muscles are the moving power, and the brain and nerves are the vital agents, which set the machinery in motion. Muscles alone have the power of contraction, and it is one of the most remarkable properties of life. Were it not for this, the food could not be digested, the blood could not be

circulated, and the iris could not guard the eye against the admission of too much light, which would speedily destroy the vision.

5. The shape of muscles is various, some are round, some flat, and the fibres of which they are composed, are connected by means of cellular membrane. Some are penniform, or made of bundles of fibres, diverging from a central line, like the feathers of a quill Muscles compose a large part of the bulk of the body; and when they contract, the fibres shorten and become harder, as may easily be perceived by placing one hand on the middle of the arm and bending the elbow, or on the temple and closing firmly the lower jaw.

6. The force with which a muscle contracts, depends on the physical condition of the muscle and the energy of the brain When the fibres of the muscle are large and firm, they will contract with more force than when they are small, soft, and delicate. We see some persons, who labour under great mental excitement, perform astonishing feats of strength, although, perhaps, they may not have muscles of the ordinary size.

7. The knee-pan has often been split in two by the contraction of the muscles of the leg; a horse has been known to break its under jaw by biting a piece of iron. Men have been known to lift eight and nine hundred pounds weight; to break ropes two inches in circumference, and to bend a round piece of iron, a yard long, and three inches in circumference, to a right angle, by striking it across the left arm, between the shoulder and the wrist, with the right hand.

8. The force of muscular contraction is greatly increased by exercise.) The strength of an active man labouring to the greatest possible advantage, is estimated to be sufficient to raise ten pounds, ten feet in a second, for ten hours in a day); or to raise one hundred pounds, one foot in a second,

* See Dunglison's Physiology.