120 Mr. R. Moon on the Structure of the Human Ear, and on 



though erroneous mode of viewing the subject had its natural 

 influence — a false theory leading to false assumptions as to mat- 

 ters of fact — and for a long time prevented my recognition of 

 the truth of which I was in search, and which I now proceed 

 forthwith to establish, viz. that waves of condensation may be left 

 out of account in considering the phenomena of aereally transmitted 

 sound. 



The structure of the human ear is described by anatomists 

 with a lucidity and precision than which nothing can be more 

 admirable ; but when we turn from the accounts of the structure 

 to the accounts of the functions of the different parts of the organ, 

 all is confused and contradictory*. The subject is undoubtedly 

 beset by great difficulties, two of which have been very generally 

 felt and recognized : — (1) that arising from the supposed double 

 transmission of motion from the tympanal membrane to the la- 

 byrinth, viz. through the bones of the ear and by means of the 

 air in the tympanal cavity — in other words, through the fenestra 

 ovalis and through the fenestra rotunda; (2) that due to the 

 fact that very considerable power of hearing, even articulate 

 sounds, often remains after the tympanal membrane has been 

 removed, and the chain of bones hangs loose in, or is absent 

 from the cavity. 



Nevertheless I cannot but think that the great difficulty has 

 consisted in the unaccountable and unfortunate propensity f 

 which, so far as I am aware^ has characterized every writer on 

 the subject, of considering the effect upon the ear of condensed 

 waves alone — the efforts of each investigator being thus confined 

 to examining the effect of a particular kind of wave upon an 

 organ which, as I hope to show, has been expressly contrived so 

 that waves of that kind shall produce upon it no effect whatever. 



* Take, for example, the testimony of Sir John Herschel, delivered so 

 far back as the year 1830, hut the justice of which at the present time, I 

 apprehend, few will be inclined to dispute. 



" Of all our organs, perhaps the ear is one of the least understood .... 

 In the ear everything is ... . obscure. It is not with it as with the eye, 

 where the known properties of light afford a complete elucidation of the 

 whole mechanism of vision, and the use of every part of the visual ap- 

 paratus." 



" In the cavity behind the tympanum is placed a mysterious and com- 

 plicated apparatus " [the bones of the ear]. See Ency. Met. Art. Sound, 

 Nos. 319, 320. 



t This propensity is the more surprising when we remember that no one 

 has ever supposed waves of rarefaction to be without their influence in the 

 production of sound, that the least consideration suffices to show that 

 either kind of wave may be propagated without the other, and that in a 

 great number of instances, as for example the sounds produced from a 

 kettledrum, where both kinds of waves occur, rarefied waves head the 

 column. 



