Royal Sucicfj/. 287 



will be, Upon hard turf 7j 



hard loam 9^ 



ordinary bye- road 1 7 



newly gravelled road 2 2 



loose sandy road 3 1 



I am, gentlemen, yours truly, 



Leighton Bussard, 13th March, 1830. B. Bevan. 



o 



XLIII. Proceedhigs of Learned Societies. 



ROYAL SOCIETY. 

 kN the anatomy and physiology of the internal ear, by T. W. Che- 

 valier, Esq. ; communicated by Charles Bell, Esq. F.R.S. 

 The author denies the correctness of the commonly-received opi- 

 nion, that sounds are modulated in their passage through the tym- 

 panum of the ear J and believes that the vibrations are transmitted 

 without modification to a medullary substance, which he thinks may 

 be regarded as a process of the brain itself. He refers, for the proof 

 of this proposition, to a paper of which he is the writer, published in 

 the 13th volume of the Medico-Chirurgical Transactions j^and in which 

 he endeavours to show that the malleus and the incus are so closely 

 united by ligaments, as to preclude the possibility of their moving as 

 levers upon each other. The author lays it down as a fundamental 

 proposition, that every sound is characterized by three properties, 

 which are quite distinct from one another. The first of these is 

 its degree of loudness ; the second its tone ; and the third its (jua- 

 litv or kind. He conceives that the ear is capable of effecting a me- 

 chanical separation of these three properties ; and of distributing 

 them on different portions of the organ, — without, however, destroy- 

 ing their physical unity : and he claims to himself the originality of 

 the discovery of the several portions of the nerve of hearing on which 

 these different properties of sound are respectively impressed. That 

 part of the organ which is adapted to distinguish the loudness of 

 sound he terms the biameter; that which conveys the perception of 

 differences in tone he calls the tonometer; and thirdly, to that portion 

 of the internal ear which is impressed by differences in the quality of 

 sound, he applies the denomination of poionieter. He regards the 

 cochlea as performing the function of biameter, viewing it as being 

 essentially a conoidal tube, which is coiled into a spiral form merely 

 for the sake of greater compactness and strength ; for he observes, 

 that in the ears of singing birds, where compactness is no object, the 

 cochlea is a straight tube. In order to explain his view of the office 

 of this part of the ear, he assumes it as a princijjle, that where a li- 

 quid is propelled through a conoidal tube, its pressure against the 

 sides is inversely as the square of the area of a transverse section of 

 the tube. This pressure, in the case of the seals of the cochlea, will 

 be greatest at their apices. Hence, tlie impression of sound will be 

 greatest at this part, and will diminish in regular gradation according 

 as we trace the tubes from this part to their wider extremities ; — so 



that 



