which fixes the attention, with extreme earnestness, on an abstruse subject, rivets the mind on a single point, requiring the closest discrimination, or leads it away in a train of abstract thought: let there be, in one word, what we term a "breathless" attention; and we observe the person at once in the situation which we designate by the common phrase, "holding the breath." The reader, so situated, neither attempts to inhale a fresh breath, nor to let go that which he has inhaled; his chest becomes, as it were, fixed and immovable; in the intensity of his attention to a mental object, he forgets and neglects the organic demands of the vital processes; he unconsciously sympathizes with the stimulated condition of his brain; and his nervous energy takes that direction, to the suspension, almost, of the functions of breathing, and even of circulation, and digestion, hence the enfeebled state of the lungs, the paleness of the countenance, and the coldness of the extremities, which attend close mental application, when intense or long continued. Such is the condition of the human being, under the spell of the intellectual instincts, when nature is absorbing the powers of life, for the purposes of fixed thought, and is forbidding utterance, or expression, or any external manifestation of mind. Voice is, in such circumstances, silenced; and the organs are, for the time, irrevocably closed, by the stricture which is thrown over them.

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But let us continue our observation of this silent reader; and we may perceive, perhaps, an immediate and entire change of phenomena. The spell of irresistible attraction in the page of the book, has ceased; the cloud of perplexity has passed away; the difficulty is solved; the discrimination is made; the doubt is cleared up; or the train of thought is come to an issue. As a consequence, the rigor of the brow relaxes; a radiant smile takes its place; the suspended breathing is resumed, with a deep and full expiraration, which seems to let go the imprisoned functions; the returning blood restores its hue to the cheek and the lip; animation once more sparkles in the eye; the heart resumes the throb of life; and a genial glow is diffused over the whole frame; an exclamation of joy, perhaps, succeeds; and a friend standing near, is invited, in cheerful accents, to partake the intellectual pleasure of the reader. The ef fect on the organs of speech, in such circumstances, is, then, that the breath is no longer held: the struggling prisoner

escapes in a sigh of instinctive, reactive effort, or in an exclamation of delight.

The practical lesson here taught, is, that utterance demands a free expulsion, not less than a deep inhalation of breath; that there must be a vigorous consentaneous action of the will, along with the silent involuntary process of nature.

The full function of expiration, when carried to the extent of exclamation, as in the case supposed, implies an energetic use of the lower muscles of the trunk, those which are termed the abdominal,* -to impart, by upward and inward impulse, a powerful percussion to the diaphragm, by which the breath contained in the air-cells of the lungs, is forced through the bronchial tubes and the trachea, towards the glottis and the larynx, where it is converted into sound, and thence into and through the mouth, and the cavity of the head, where it is modified into speech, by the action of the nasal passage, the tongue, the palate, the teeth, and the lips, in the various functions of articulate utterance.

The engraved figures will serve to impart a clearer idea than can be conveyed by words, of the place and form of the vocal organs, together with their action in the production of sound.

Figure 1 represents the principal abdominal muscle, by which the first expulsory movement terminating in sound, is produced. The action of this muscle, in energetic and abrupt forms of utterance, is nearly the same in kind, though not in degree, with that which takes place in the sudden shrinking from a blow, aimed at or below the stomach. In vigorous utterance of a steady and sustained character, or in the energetic singing of long notes, a powerful and continued upward and inward pressure of the abdominal muscles, takes place, as in the attitude observed in swift riding on horseback.

2. The diaphragm, which by an upward impulse, consentaneous with that of the abdominal muscles, and imparted to the pleura, or enveloping membrane of the lungs, forces the air from their cells into the bronchi, and thence into the trachea and the larynx.

* In shouting and calling, and other violent exertions of voice, the dorsal muscles, those of the lower part of the back, — partake in the expulsory effort.

3. The thorax, the great cavity of the chest. By the expansion and compression of this capacious organ, the process of breathing is conducted; and by its resonance, the voice receives depth and volume.

4. The intercostal muscles, at the lower, and

5. The thoracic and pectoral muscles, at the upper part of the chest, serve to dilate and compress it, in the acts of breathing and of utterance.

6. The pleura is a membrane which envelopes the lungs, and propagates to their cells the impulse by which these are emptied of their successive supplies of air inhaled at the intervals of speaking or singing.

7. The lungs, a spongy body, consisting of two lobes, into the cells, or little cavities, of which, the air inhaled in breathing, is drawn, and from which it is expelled by the impulse communicated, as mentioned before, by the pleura, and derived from the diaphragm and the abdominal muscles.

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8. The bronchi, or two main branches of the trachea, or wind pipe. These two tubes are themselves subdivided into many subordinate and minute ramifications, which serve to distribute to the air-cells of the lungs, in which they terminate, the breath which is inhaled through the trachea, and to convey that which is expelled from the lungs, by the impulsive action of the diaphragm, into the trachea, the larynx, and the mouth.

9. The trachea, or wind-pipe, a series of connected cartilaginous, or gristly, rings, forming the great air-tube, which receives and conducts the breath to and from the lungs, in the acts of inspiration and expiration, and in the function of utterance.

10. The larynx, a cartilaginous box, on the top of the trachea, the exterior projection of which is familiarly called the Adam's apple, in allusion to the fabled origin of this part, which was anciently said to have owed its existence to Adam's fatal offence in swallowing the forbidden fruit. The whole larynx is the immediate seat and general instrument of vocal sound. The portions of this organ, which are immediately concerned in the production of sound, are,

11. The cricoïd cartilage, situated immediately over the uppermost ring of the trachea, resembling, in form, a sealring, from which it takes its name, but having the broad part at the back, and the narrow in front. The form and position of this portion of the larynx, admit of the eleva