380 



NOTES AND QUERIES. 



[2'«i S. VII. May 7. '59. 



his "little book," were well known in the days of 

 my childhood — more than thirty years ago — 

 when I verified them. I know not how I came to 

 try them — whether from oral instruction or from 

 reading — but certainly I found them amply de- 

 tailed in a " little book," somewhat grandly en- 

 titled — The Modern Cabinet of Art, a Series of 

 entertaining Experiments, SfC. 8fc., by T. C. Thorn- 

 ton, published in 1841 : — a very useful and curi- 

 ous little book, far superior to those now teeming 

 from tlie press, of similar import, with various 

 titles. But Thornton does not talk of " hearing 

 with the teeth : " — he heads his article scientifi- 

 cally : — " The travelling of sound experimentally 

 proved." I quote the whole for the purpose of 

 comparison with the recent information : — 



" There is probably no substance which is not in some 

 measure a conductor of sound: but sound is much en- 

 feebled by passing from one medium to another. If a 

 man, stopping one of his ears with his finger, stop the 

 other also by pressing it against the end of a long stick, 

 and a watch be applied to the opposite end of the stick, 

 or a piece of timber, be it ever so long, the beating of the 

 watch will be distinctly heard; whereas, in the usual 

 way, it can scarcely be heard at the distance of fifteen or 

 eighteen feet. 



" The same effect will take place if he stop both his ears 

 with his hands, and rest his teeth, his temples, or the gristly 

 part of one of his ears against the end of a stick. 



" Instead of a watch, a gentle scratch may be made at 

 one end of a pole or rod, and the person who keeps the ear in 

 close contact with the other end of the pole will hear it 

 [the scratch] very plainly. Thus, persons who are dull 

 of hearing, may, by applying their teeth to some part of 

 a harpsichord, or other sounding body, hear the sound 

 much better than otherwise, 



" If a person tie a poker, or any piece of metal, to the 

 middle of a strip of iiannel about a yard long, then press 

 with his thumbs or fingers the end of the flannel into 

 Lis ears, whilst he swings the poker against any obstacle, 

 as an iron or steel fender, he will hear a sound very like 

 that of a large church bell." (Ubi supr^, p. 335.) 



The fact that Thornton mentions the " temple " 

 as one of the sound-transmitting points is remark- 

 able. Often have I asked anatomists and physio- 

 logists the reason for the striking thinness of the 

 skull over the ears and the temples, but could 

 never get a " because" for the "why" — after the 

 manner of Aristotle. It seems evident now that 

 Nature made the bone thin over the organs of 

 hearing for the purpose of favouring the trans- 

 mission of sound or aerial vibrations. 



The facts advanced by Thornton and Mb. 

 PiESSE are easily explained. I must premise that, 

 strictly speaking, it is incorrect to say that we see 

 with the eyes or hear with the ears ; and so on, 

 with respect to all the senses : — the perception is 

 in the brain : it is the brain which sees, hears, &c. : 

 — the eyes, ears, &c., are merely the means of the 

 respective perceptions. Nay, more, the terms 

 " eyes," " ears," &c., are far too comprehensive, 

 as they consist of numerous parts or mechanisms 

 more or less essential to the function which is sub- 



served. This complexity of construction is an 

 instance of the Creator's wisdom and benevolence, 

 — since the accidental injury of one or more parts 

 does not necessarily destroy the sense, provided 

 the injury does not reach the most essential part 

 or mechanism. 



The organ of hearing is said to be " the most 

 noble and the most intellectual of the senses." 

 (Meckel, Manual of Descrip. and Pathol. Anat.') 

 It is formed of a considerable number of parts, 

 differing very much in their form and texture — 

 all very interesting to study — but we must here 

 confine ourselves to the part or mechanism which is 

 the cause of what has been called " hearing with 

 the throat and by the teeth " — namely, the Eusta- 

 chian tube, or guttural conduit of the ear. It ex- 

 tends from the tympanum or drum of the ear to 

 the upper part of the pharynx, and is lined inter- 

 nally by a very fine mucous membrane which is 

 continuous with that of the mouth and of the 

 tympanum : — in fact, the Eustachian tube is a 

 passage which extends directly from the posterior 

 part of the tympanum into the fauces — in other 

 words, into the throat. It thus maintains a com- 

 munication between these two cavities, and con- 

 sequently between the external air and that 

 enclosed within the tympanum which is always 

 full of air. The little muscle, called tensor tym- 

 pani, which tightens the drum of the ear so as to 

 make it vibrate in accordance with sharper or 

 higher tones, is actually lodged in the Eustachian 

 tube. The proper vibration of the membrana tym- 

 pani is connected with the state of the air in the 

 Eustachian tube, as in examining the ears of dif- 

 ferent kinds of animals, the membrane and the 

 tube are always found together, and there are 

 many pathological facts which prove that the in- 

 tegrity of the Eustachian tube is essential to 

 the perfect function of the ear. "N^Tien, from 

 any cause, this passage becomes closed or ob- 

 structed, the hearing is very materially impaired, 

 whilst it is restored by removing the obstruction. 

 (Broc, Traits d'Anatomie ; Carpenter, Physiol., 

 Bostock, Physiol.) Nevertheless, the participa- 

 tion of the Eustachian tube in hearing is not direct: 

 if so, we should hear our own voice when speak- 

 ing loudly after stopping the ears ; but this is not 

 true. The Eustachian tube has been compared 

 to the hole without which the air in a military 

 drum would not vibrate ; and its principal func- 

 tion is to renew the air in the tympanum, and also 

 to excrete the mucus and the condensed perspira- 

 tion constantly secreted by the lining membrane 

 of this cavity. (Meckel, ubi supra.) 



It is now obvious to the reader that hearing by 

 the teeth and by the throat is merely the trans- 

 mission of sound through the Eustachian tube to 

 the auditory nerve by means of the tympanum, 

 which enables the brain to form the perception of 

 sound. The result is also aided by means of the 



