Mechanism of the Larynx. 327 



mentis. I shall now proceed to a more minute examination of the 

 precise nature of this vibration, and of the mechanism of the Larynx 

 generally than appears to have been hitherto attempted. Assum- 

 ing - then that the source of the notes of the voice is to be found 

 in the vibrations of a pair of membranous elastic edges, between 

 which a current of air is allowed to pass, I shall endeavour to 

 shew under what conditions such elastic edges must be presented 

 to a current of air, in order that it may elicit from them the re- 

 quired vibrations. 



One of the most commodious ways of investigating this is to 

 prepare a piece of wood of the form ABCD (Fig. 9) and paste 

 on one side of it a piece of fine kid leather, the upper end of 

 which {mn) is cut straight, and a moderate degree of tension given 

 to the leather when pasted on. 



This arrangement presents us with an elastic membrane, whose 

 upper edge mn is free and the other edges confined, and, therefore, 

 with a case analogous to that of the vocal ligaments. 



EF (Fig. 10) is the plan of a flat board, having a rectangular 

 opening GH in the middle, and LM (Fig. 12) is a vertical section 

 of this board along the line IK, (Fig. 10,) shewing a pipe 2V 

 attached to the lower side of the board, in order to connect it 

 with a pair of organ bellows, by means of which a current of 

 air may be maintained through the rectangular opening at pleasure. 

 (In Figs. 14, 16, and 18 are similar sections). 



Let now an upright board OP, (Fig. 12,) be clamped upon 

 LM, so that its face P may coincide with the side of the opening 

 throughout its whole length. If the leather in its frame, (Fig. 9,) 

 be exposed to the action of the current by placing the lower edge 

 BC of its frame in contact with this board and always parallel 

 to the side of the opening, and if then the frame be turned on 



