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bility of sudden alterations of bulk ; the author briefly adverts to the 

 unsatisfactory explanations which have been offered as to its function, 

 and then proceeds to state his own views, as follows : 



" The upper part of the trachea, the larynx, and the passage of the 

 fauces and mouth constitute the organ of voice ; the two former are 

 the essential or voicing part as mechanicians call it, that which pro- 

 duces the tone. The larynx and trachea taking a share in other 

 functions and being associated by juxtaposition and attachment with 

 contiguous organs are always pervious and open for respiration ; 

 lengthen and shorten, fall and rise with the oesophagus in deglutition, 

 and bend and turn with the universal motions of the head and neck. 



" To admit of this great mobility and flexibility, a certain structure 

 is necessary. The larynx is a triangular box enclosing the apparatus 

 of the chordae vocales ; its two cartilaginous sides or alse, diverging 

 from the front, are not fixed but free at the back, being completed 

 by soft parts : the trachea is composed of a succession of incomplete 

 cartilaginous hoops or rings lying apart, the back arid intervals being 

 made up and the tube completed by soft membrane. 



"Now the structure of a wind instrument, such as that of the 

 human voice is, requires the very opposite properties. It must be 

 rigid, tense and inflexible. The qualities of the tone will be in exact 

 proportion to these properties. How then is the soft, slack and 

 flexible vocal tube rendered thus rigid, tense and inflexible, and fit to 

 produce pure tone ? The muscles of the larynx, the thyro-hyoid and 

 sterno-thyroid, merely raise or lower, or fix it in any position : not 

 lying on, or being parallel to, but diverging from the vocal tube, they 

 cannot effect the object referred to. It appears to me that the 

 thyroid body is provided for this purpose. The act of uttering a 

 tone or of speaking stops the return of the blood from that organ, 

 distends and renders it tense, and from the nature of its attachment 

 round the top of the trachea and on the free sides of the alae of the 

 larynx, renders them fixed, firm, and tense also. This effect is aided 

 by the aforesaid muscles, the thyroid body being interposed and 

 giving them more advantageous mechanical action. This tension 

 may be in any degree, and on energetic speaking or singing, the in- 

 creased size of the part and the fulness of the collateral veins may 

 be seen. This is the reason of its large supply and free distribution 

 of blood. An instance of the want of this tension in an instrument 



