HELMHOLTZ IN BONN 



ing the round window passes outwards, and thus a 

 to-and-fro pressure is communicated to the fluid 

 in the sacs and tubes with each pressure of a wave 

 of sound. 



Helmholtz emphasizes strongly a remark first made 

 by Riemann, that the dimensions of the internal ear are 

 so small as to form only a small part of the wave- 

 lengths, even of tones of high pitch. The whole of 

 the membraneous labyrinth may be regarded as part 

 of any wave acting on the ear, and the wave is not 

 arrested by the labyrinth as waves of light are arrested 

 by the retina, but they sweep onwards through the 

 bones of the head. The fact of the labyrinth being 

 so small, relatively to the size of the wave, makes no 

 difference in the result ; so that the labyrinth is acted 

 on in the same way, whether the ear receives a wave 

 of thirty feet in length, such as is produced by the 

 longest pipe in a modern organ, or a wave of two- 

 thirds of an inch, produced by the highest note of a 

 piccolo flute. The nerve-endings are very much 

 smaller, but they also act as minute portions of any 

 wave, and any reasoning as to the effect of such 

 waves is quite irrespective of the small dimensions of 

 the receiving organs in the internal ear. This point 

 is of great importance in the consideration of the 

 theory of hearing advanced by Helmholtz. 



It is clear, then, that the number of movements 

 communicated to the structures in the internal ear 

 in, say a second of time, depends on the pitch of the 

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