OF THE HUMAN VOICE. 
569 
plex, but as a simple apparatus; with some the favourite hypothesis has accordingly 
been that of musical strings, with others that of a reed, whilst experiments are 
equally in favour of both. 
It cannot be expected that in this brief treatise, a subject, wherein, notwithstand- 
ing the attention hitherto bestowed on it for many years by men of the highest 
philosophical talent, so little comparatively has been effected, shall be at once ex- 
hausted, and all its difficulties removed ; but the inductive method, the only satisfac- 
tory mode of reasoning on such subjects, has been most scrupulously pursued, and 
whatever explanations have been offered of the phenomena of the voice are at least 
founded on facts which are incontrovertibly established. 
Description of the Plates. 
PLATE XXX. 
Figs. 1 and 2. The internal structure of the larynx brought into view, by making a 
transverse section through the central portion. 
YY'. The plane of the vibrating position of the vocal ligaments. 
XX. The plane of the respiratory position in which the vocal ligaments 
are found to lie in their most relaxed state. 
Figs. 1' and 2' are outlines descriptive of figs. 1 and 2. 
Fig. 1'. Anterior section of the larynx. 
n. The epiglottis. 
mm. Os hyoides. 
ee. Internal surface of the thyroid cartilage. 
ff. The cricoid cartilage. 
dd. Thyro arytenoid muscles. 
gg. The ventricles of Morgagni. 
cc. Inferior vocal ligaments. 
k. The trachea. 
Fig. 2'. a. The pharynx. 
b. The arytenoid cartilages. The letters c,f,d,k , &c. represent the parts 
corresponding to the same letters in fig. 1'. 
4 E 
MDCCCXLVI. 
