OF THE LARYNX, AND ITS ACTIONS. 851 



feet; and the conditions necessary to produce the higher notes from it, are 

 by DO means those which we find to exist in the process of modulating the 

 human voice. 



696. We now come to the third class of instruments, in which sound is 

 produced by the vibration of reeds or tongues ; these may either possess 

 elasticity in themselves, or be made elastic by tension. The "free" reeds 

 of the Accordion, Concertina, Seraphine, Harmonium, etc., are examples of 

 instruments of this character, in which the lamina vibrates in a sort of frame 

 that allows the air to pass out on all sides of it through a narrow channel, 

 thus increasing the strength of the blast ; whilst in the Hautboy, Bassoon, 

 etc., and in the Organ pipes of similar construction, the reed covers an aper- 

 ture at the side of one end of a pipe. In the former kind, the sound is 

 produced by the vibration of the tongue alone, and is regulated entirely by 

 its length and elasticity ; whilst in the latter its pitch is dependent upon this 

 conjointly with the length of the tube, the column of air contained in which 

 is thrown into simultaneous vibration. Some interesting researches on the 

 effect produced on the pitch of a sound given by a reed through the union 

 of it with a tube, have been made by M. W. Weber ; and, as they are im- 

 portant in furnishing data by which the real nature of the vocal organ may 

 be determined, their chief results will be here given. I. The pitch of a reed 

 may be lowered, but cannot be raised, by joining it to a tube. n. The sink- 

 ing of the pitch of the reed thus produced is at the utmost not more than an 

 octave, in. The fundamental note of the reed thus lowered may be raised 

 again to its original pitch by a further lengthening of the tube, whilst by a 

 further increase it is again lowered, iv. The length of tube necessary to 

 lower the pitch of the instrument to any given point, depends on the relation 

 which exists between the frequency of the vibrations of the tongue of the 

 reed, and those of the column of air in the tube, each taken separately. 

 From these data, and from those of the preceding paragraph, it follows that 

 if a wind instrument can, by the prolongation of its tube, be made to yield 

 tones of any depth in proportion to the length of the tube, it must be re- 

 garded as a flute-pipe; whilst if its pitch can only be lowered an octave or 

 less (the embouchure remaining the same) by lengthening the tube, we may 

 be certain that it is a reed instrument. The latter proves to be the case in 

 regard to the Larynx. 



697. It is evident from the foregoing considerations, that the action of the 

 Larynx has more analogy to that of reed instruments, than it has to that 

 either of vibrating strings, or of flute-pipes ; and though there would seem, 

 at first sight, to be a marked difference in character between the vocal liga- 

 ments and the tongue of any reed instrument, this difference is really by no 

 means considerable. In a reed, elasticity is a property of the tongue itself, 

 when fixed at one end, the other vibrating freely; but by a membranous 

 lamina, fixed in the same manner, no tone would be produced. If such a 

 lamina, however, be made elastic by a moderate degree of tension, and be 

 fixed in such a manner as to be advantageously acted on by a current of air, 

 it will give a distinct tone. It is observed by Miiller, that membranous 

 tongues made elastic by tension may have either of three different forms: 

 I. That of a band extended by a cord, and included between two firm plates, 

 so that there is a cleft for the passage of air on each side of the tongue. 

 n. The elastic membrane may be stretched over the half or any portion of 

 the end of a short tube, the other part being occupied by a solid plate, be- 

 tween which and the elastic membrane a narrow fissure is left. in. Two 

 elastic membranes may be extended across the mouth of a short tube, each 

 covering a portion of the opening, and having a chink left open between 

 them. This last is evidently the form most allied to the Human Glottis ; 



