Prof. A. M. Mayer's Researches in Acoustics. 445 



elusions relative to the mudus operandi of the physical forces to 

 which this system of philosophy seems to point are : — that they 

 are all modes of pressure of the aether; that the forces concerned 

 in light, heat, molecular attraction and repulsion, and gravity 

 are dynamical results of vibrations of the aether ; and that elec- 

 tric, galvanic, and magnetic forces are due to its pressure in 

 steady motions, 



Cambridge, October 16, 1874. 



LVIII. Researches in Acoustics.- — No. V. 

 By Alfred M. Mayer. 



[Continued from p. 385.] 



4, Suggestions as to the Function of the Spiral Scalce of the 

 Cochlea^ leading to an Hypothesis of the Mechanism of Audi- 

 tion. 



AS the auditory nerve has by far its highest development in 

 the cochlea, it is a natural inference that this part of the ear 

 is chiefly concerned in audition, and that the very peculiar form 

 of the cochlea fulfils some important function; yet the rela- 

 tions of this form to the mode of audition have occupied but 

 little the attention of physiologists. The only suggestion as to 

 the uses of its form with which I am acquainted is that given 

 by Dr. J. W. Draper in his ' Physiology/ N. Y., 1855. This 

 distinguished philosopher states that " it may be imagined how 

 it is that a sound passing through the auditory canal, the bones 

 of the tympanum, the membrane of the fenestra ovalis, and thus 

 affecting its destined portion of the lamina, does not give rise to 

 an idea in the mind of repetition or reverberation by moving 

 back and forth through the two scalse and affecting its proper 

 nerve-fibril at each passage. Is there not a necessity for the 

 exertion of some mechanism of interference which shall destroy 

 the wave after it has once done its work ? " Dr. Draper then 

 reasons that this reverberation is prevented by the scalse being 

 of different lengths and by the fact of their junction in the heli- 

 cotrema. These two circumstances give rise to interferences in 

 the helicotrema of the waves which have proceeded from the 

 stapes up the scala vestibuli with the waves which passed from 

 the membrana tympani across the tympanum to the fenestra ro- 

 tunda, and thence up the scala tympani to the helicotrema. 

 Dr. Draper also states that when the stapes is pushed in by the 

 contractions of the tensor tympani and stapedius muscle, the re- 

 lative length of the scake is changed, and thus the proper ad- 

 justment for an interference is effected. But even granting that 



