THE LARYNX, AND ITS ACTIONS. 



303 



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. 

 II. The sinking of the pitch of the reed thus produced, is at the utmost not 

 more than an octave. III. The fundamental note of the reed thus lowered, 

 may be raised again to its original pitch, by a further lengthening of the 

 tube ; and by a further increase, 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 vibra- 

 tions 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 regarded 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. 



408. Between the action of the Chordae Vocales, however, and that of an 

 ordinary Reed, there appears to be a marked difference ; but 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 mem- 

 branous lima, 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. II. 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, between which and the 

 elastic membrane a narrow fissure is left. III. 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; but it may be made to approximate 

 still more closely, by prolonging the 



membranes in a direction parallel to 

 that of the current of air, so that not 

 merely their edges, but their whole 

 planes shall be thrown into vibration. 

 Upon this principle, a kind of arti- 

 ficial Glottis has been constructed by 

 Mr. Willis ; the conditions of action 

 and the effects of which are so nearly 

 allied to that of the real instrument, 

 that the similar character of the two 

 can scarcely be doubted. The fol- 

 lowing is his description of it. " Let 

 a wooden pipe be prepared of the 

 form of Fig. 78, having a foot C like 

 that of an organ-pipe, and an upper 

 opening, long and narrow, as at B, 

 with a point A rising at one end of 

 it. If a piece of leather, or still 

 better, of sheet India Rubber, be 

 doubled round this point, and se- 

 cured by being bound round the 



Fig. 78. 



Fig. 79. 



Artificial Larynx. After Willis. 



