SENSE ORGANS. 211 



strings must be tense in order to vibrate elastically at 

 all, and since, further, other things being equal, they 

 make higher pitch in proportion as they are shorter, it 

 is evident that strings of any such length as this, if 

 tense enough to vibrate at all, could only produce an 

 inconceivably high note. But see the range of the voice ! 

 To what, then, shall we compare it ? 



It is strange that no one has thought to compare it to 

 an ordinary horn — a stage horn, for example, or, better, 

 a French horn. In this instrument the sound is modu- 

 lated exactly as in the larynx — viz., by the tension and 

 the pressing together of the lips of the performer. The 

 edges of the rima glottidis ought to be called the vocal 

 lips, as indeed they are, and not the vocal cords, which 

 they are not in any sense. The analogy between the 

 two instruments is perfect. The performer on the horn 

 presses his lips together tighter, and makes them tenser 

 and the opening between them smaller in proportion as 

 he desires a higher note. He then drives the air between 

 the tense lips so as to set their edges in vibration ; this 

 vibration, by alternate partial closing and opening of the 

 aperture, gives rise to successive jets or pulses of the 

 out-driven breath, and this in its turn gives correspond- 

 ing pulses to the air in the sounding cavity of the horn. 

 Precisely the same, as we have seen, takes place in the 

 larynx. The only wonder is that so small an instrument 

 as the larynx and the mouth cavity should be capable 

 of such marvelous effects. 



3. SPEECH. 



Of course the subject of speech concerns other sci- 

 ences besides physiology. But the mechanism of the pro- 

 duction of the various sounds used in speech belongs to 

 physiology alone. We need no apology, therefore, for 

 taking it up briefly. 



