Yawning is caused by debility or the sluggish action of the muscles of respiration, and consequently a diminished force in the circulation; and a smaller quantity of air is admitted to the lungs and carbonic acid gas being accumulated in the bronchiæ, nature makes this effort to dispel the torpor and relieve the air cells.

Snoring is effected by the inactivity of the muscles of the extremities, in consequence of which the blood returns more sluggishly to the heart; some of the muscles of respiration are thus impeded, and the remainder have to labor more violently to overcome the deficiency, for the lungs require a certain quantity of air to preserve their function; what they fail in receiving in the regular inspirations they make up by more frequent inhalations, and what they want in the frequency of inspirations, they endeavor to compensate by the quantity admitted. In snoring, the mouth is besides but slightly extended, the palate is depressed, a larger volume of air is admitted into the nose, and hence the peculiar nasal resonance.

Sneezing results from the irritation of the membrane lining the nasal cavity and the sudden action of the muscles of respiration. Nature here strikingly shows the precautions she has taken to expel irritating bodies from the nose. The entrance from the mouth to the nares is guarded by the velum palati, and in sneezing, this part of the roof of the mouth is greatly depressed, the passage of course is more open and the exit by the mouth more hindered, and hence the peculiar nasal sound.

Hiccup arises from the spasmodic action of the diaphragm compressing the lungs with more or less violence. The length of time between two successive inspirations cannot be always fixed, for habit, circumstances, and the will, cause such alterations in this interval as to strike with surprise many unacquainted with the fact.*

When these inspirations are partial, short and quick and are modified by the position of the mouth, we have sobbing or sighing.

Groans are labored, deep and lengthened expirations. Laughing is a continued expiration, with catches, or more properly there is, at intervals, from the action of the diaphragm and muscles of the chest, an increased velocity in the exit of the air. These inarticulate sounds are little affected by the larynx, whilst other modifications of the human voice which are used to convey ideas, are so de

* The pearl divers of India have accustomed themselves to exert the muscles of respiration so as to admit a larger quantity of air than usual and thus endure an absence from the open air, which is truly wonderful.

pendent on this organ that it will be proper to give it some attention. The larynx is an irregular tube somewhat resembling a truncated cone. It is composed of the two arytenoid, the thyroid and the cricoid cartilages, besides the epiglottis, making in all five cartilages with their ligaments, nerves, veins and absorbents, also nine muscles, two glands and four arteries, and their branches; all these are also separately essential, to the perfection of the human voice and generally the absence or diseased state of one of these parts has a striking influence on the tones. Hunter proved, that the music of the males of singing birds was produced partly by a greater developement of the muscles of the larynx.

Women have a smaller larynx than men and some physiologists have made the difference greater, than is actually found by examination.

Females of licentious habits lose so far their effeminate vocal distinctions, as to have little in their utterance, to distinguish them from males.

Age exerts no inconsiderable power in altering the tones, for infancy, puberty, manhood and the senile state bring with them their peculiar intonation.

Not only the use of the muscles of the larynx, but the exercise of the muscles of the chest as we see in the blacksmith, increases the power of the voice. The size of the chest, lungs and trachea all bear on the force of the utterance and to demonstrate this, we have only to allude to the lion whose capacious trachea and the muscular strength of whose chest, render his roaring an object of terror to the beasts of the forest. On the other hand when the quantity of air emitted is small and the velocity diminished, the sounds become soft and low, and make an impression on the ear like an echo, because the vibrations are not so rapid. This consideration is important in explaining the art of ventriloquism, which we shall shortly notice.

In grave tones, the velum palati is lower, leaving the entrance to the larynx more open, the larynx is depressed, and the cavity of the mouth is elongated: the contrary occurs in the acute sounds, the passage to the nose is more obstructed by the ascent of the velum palati, the larynx is raised, the opening of the glottis decreased and the rapidity of the air, passing through it is increased, and the depth of the oral cavity diminished.

Thus we see that the extent of the vocal cavities and their position have great effect on the voice, and this should not be lost sight of in treating of ventriloquism.

To produce intensity in the voice we all know that the mouth is open, the velum palati raised and the position is nearly the same as `in declamation, and all who have seen ventriloquists must be convinced, that they cannot practise their art and use the mouth as those who wish to be heard at a distance, for in the latter case the stock of air is rapidly exhausted and the principal requisite for ventriloquists is to hold this collection for use. It is curious that the attention of physiologists has not been directed to the action of the muscles of the thorax and more especially of the diaphragm, in accounting for ventriloquism. The muscles called into action during inspiration are the internal and external inter-costales, the diaphragm and the subclavius which are occasionally assisted by the latissimi dorsi, the pectoralis, the scaleni, the sterno-mastoidei, the serrati magni and the serrati postici superiores.

In expiration, the muscles that act are the diaphragm (which dilates,) the recti, the obliqui externi, and the interni abdominis, the sterno-costales and the transversales, aided sometimes by the longissimi dorsi, the serrati postici inferiores, the serrati magni, the quadrati lumborum and the pyramidalis. The diaphragm is relaxed in expiration and consequently rises, which movement I may compare to the resilience of a sponge from which a contracting force has been removed and of course it expands, and thus this muscle presses on the pleura and lungs, and altering the force of the current of the air from the lungs as it acts with more or less vigor. The diaphragm or midriff contracts in inspiration and the force and extent of its contraction must regulate the quantity of air admitted into healthy lungs. I have referred to the power of pearl divers in this respect and the application is equally appropriate to ventriloquists.

Before entering on this subject, it will not be irrelevant to give the opinion of others concerning the manner in which this art is created. Formerly it was thought that ventriloquists were gifted with a double larynx and this notion may have been imbibed during the reign of comparative anatomy, but human dissection has refuted the doctrine. Richerand, at first believed, that the art resulted from the possession of the faculty of holding in the stomach, as in a store house, a larger quantity of air to be used by the performer as it was wanted. He afterwards abandoned this explanation. Mr. Gough, was less satisfactory in his doctrine of echoes; since the shape and size of the room and even the open air do not hinder the exhibiter from practising this art. The theory of Haller, Mazer De Bonn, can easily be VOL. XXVI.-No. 1.

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refuted by a ventriloquist, for constant or frequent inspirations render it impossible to perform. Fournier believed that by some singular movement of the glottis, sound was carried into the lungs and this appears to be only the opinion of Haller, rendered a little more mysterious. The theory is so contrary to all the principles of philosophy and physiology, that its mere recital is enough to condemn it in the view of those acquainted with the organization of man. Despincy believed that the glottis is open and the epiglottis pressed down. If this position were unaltered during the performance or, to speak more correctly, during the effort to speak, articulation could be shown to be impossible, and much less could the voice go through the varied tones of the ventriloquist.

Baron Manger, an excellent ventriloquist, was the first to give an idea of the art, and although he did not speak as an anatomist or physiologist, yet had others followed the clue he gave them, (A. D. 1772,) they might have been spared all their hypotheses. He said that he stored in his throat a quantity of air which he used with great labor. Now all know that air must have been retained in his lungs, and the pressing it out, at will, could not have been caused by the larynx, but by the action of the diaphragm and muscles of expiration. After this statement, physiologists neglected what ventriloquists had offered, and still attempted to work out an exposition of their own, without appealing to him that practised the art. Magendie thought it consisted of certain modifications of sound or speech, produced by a larynx of the common formation, with a strict attention to the different effects of sound thrown at different distances and through different modes of conveyance.

Here we have a maze of words and no exact knowledge is communicated from such expositions. Good thought ventriloquism, to be an imitative art, founded on a close attention to the almost infinite variety of tones, articulations and inflexions, which the glottis is capable of producing in its own region alone, when long and dexterously practised upon. But the art appears not to be always gained by practice, for I have heard ventriloquists say, that chance not discipline developed to them the possession of this art. When it is asserted, that the glottis or larynx is the only agent which is called into operation, the assumption is unsupported by examination. Hooper maintains, that ventriloquists have no organization different from that of other men; this assurance is unsupported by investigation, and if true, it amounts only to negative evidence. I do not maintain, that the

formation of ventriloquists is different from other men, but that the control they possess over the functions of respiration, is greater than is usually found in others. That this faculty produces a greater development of some muscles cannot be questioned, and it may be discovered that the nerves over which the will presides have some different and nicer distribution. He that attentively inspects a ventriloquist will notice the fixed position of the mouth and the action of the muscles of the throat in altering the situation, diameter and extent of the larynx; he will be struck with the different hue of the countenance, from obstructed respiration he will feel the diaphragm acting with a vigor and under a control not common to the generality of men, and this, combined with the action of the muscles. of expiration must exert a great influence in increasing the action of the bellows (to which I compare the thorax,) and from thence is derived the volume and force of the air that escapes by the larynx.

To prove the action of the diaphragm, I would refer the reader to the American ventriloquist, Mr. Nichols, in whom the midriff acts so powerfully on the ensiform cartilage to which it is attached, that it is not a little surprising to see the action that the xiphoid appendage possesses, and what a wonderful power it has in compressing the pleura and lungs, and also in protruding externally, and thereby increasing the volume of the the thorax, in the direction of the sternum. All ventriloquists complain of the pain attending their efforts, and this could not proceed from the exertions of the larynx alone for the uneasiness is not there, but in the chest and it can be accounted for by the action of the muscles of expiration, and the diaphragm, and sometimes from the pressure of the ensiform cartilage, which is attached to the breast bone, and united to the midriff; and moreover the uneasiness is enhanced by the retention of air in the bronchial cells. This last circumstance can be proved by the appearance of the face.

I think it strange, that the muscles of respiration have not hitherto been considered, in explaining ventriloquism, and that the quantity and force of the air which depends so much on the diaphragm, have not been objects of attention. Surgeons all know, that in case of a fracture of the ribs of the thorax, respiration is carried on solely by the midriff, and this proves its use in the animal economy. I deny the position of Good and others that this art can be perfected in all persons by practice; although most men possess the faculty of attaining to some progress in the art. That circumstances and not experimental efforts have in some instances convinced a man of his possession of the faculty is sufficient to establish this assertion.