452 Royal Society. 



concurrent action of these organs that the breath, which under 

 ordinary circumstances of respiration is inaudible, becomes vocal- 

 ized, or thrown into sonorous undulations. 



The author then gives an anatomical description of the pharynx 

 and mouth, which together constitute an irregular cavity, extend- 

 ing from the glottis to the lips and nostrils, and of which the va- 

 rious changes of dimension and of form effect corresponding 

 changes in the undulations into which the air is originally thrown 

 by the vibrations of the glottis, and produce the different modifi- 

 cations of the voice. The most important are those which con- 

 stitute articulate sounds. The simple vocal tones, or vowels, are 

 greatly modified by the mere elongation or shortening of this cavity. 

 But even in the formation of these, the contraction and appulse of 

 the pharynx acts an important part ; and in the articulation of the 

 consonants it is a principal agent; its smaller cavity being, upon a 

 well-known hydrostatic principle, substituted with great economy 

 of power for the more capacious cavity of the chest. In pronoun- 

 cing the explosive consonants, such as B, D, and G, the velum 

 pendulum is raised, and, acting as a valve, closes the posterior nares; 

 and the mouth being also closed, (he vocalized breath, which con- 

 tinues to ascend through the glottis, suffers condensation, and gives 

 rise to the faint sound which precedes the explosion consequent 

 upon the opening of the closed cavity. This opening takes place, 

 either by the separation of the lips, or by the removal of the tongue 

 from the teeth, or palate, to which it had been applied. These pre- 

 vious actions of the pharynx and glottis are the circumstances which 

 distinguish the sound of these letters from their corresponding mute 

 consonants, P, T, and K. Thus the consonants, classed according 

 to their formation in the mouth, either by the closed lips, the meet- 

 ing of the lips and teeth, or the meeting of the tongue and palate, 

 admit of varieties dependent on the actions of the pharynx and 

 velum palati. The emphasis and accent given to particular syllables 

 arise from two sources: namely, the variation in the action of the 

 chest, and in the action of the pharynx. 



This minute accommodation of action evinces not merely the per- 

 fection of the organ, but also its great subordination to the will ; 

 and in this respect the muscular apparatus of the throat admits of 

 comparison with the delicate adjustments in the eye. Stammering 

 arises, not from the defect in any single part, but from imperfect 

 power of combining the requisite actions. 



The author concludes by enumerating the variety of actions 

 which must be combined before a word is uttered : namely, the 

 compression of thethorax, the adjustment of the glottis, the elevation 

 or depression of the larynx, and the contraction of the pharynx. 

 He also adduces proofs of the correctness of the opinions advanced 

 in this paper, drawn from the effects of accident and of disease 

 occurring under his own observation ; and from which he draws the 

 following conclusions:— That the trachea gives out no sound of 

 itself; that when the area of the passage is much diminished, the 

 column of air has not sufficient force to move the chords vocales ; 



that 



