40 NATURAL THEOLOGY. 



the most beautiful applications of muscles iii the body ; tJie 

 mccha?tism is so si?7ijjle, and the variety of effects so greaty 



In another volume of the Transactions above referred to, 

 and of the same year, two most curious cases are related of 

 persons wYio retained the sense of hearing, not in a perfect 

 but in a very considerable degree, notw^ithstanding the al- 

 most total loss of the membrane we have been describing 

 Tn one of these cases, the use here assigned to that raiem- 

 brane, of modifying the impressions of sound by change ol 

 tension, was attempted to be supplied by straining the mus- 

 cles of the outward ear. " The external ear," we are told, 

 "had acquired a distinct motion upward and backward, 

 which was observable whenever the patient listened to any 

 thing which he did not distinctly hear : when he was ad- 

 dressed in a v/hisper, the ear was seen immediately to 

 move ; when the tone of voice was louder, it then remained 

 altogether motionless." 



It appears probable, from both these cases, that a collat- 

 eral if not principal use of the membrane is to cover and 

 protect the barrel of the ear which lies behind it. Both the 

 patients sufiered from cold : one, " a great increase of deaf- 

 ness from catching cold ;" the other, " very considerable pain 

 from exposure to a stream of cold air." Bad effects there- 

 fore followed from this cavity being left open to the external 

 air ; yet, had the Author of nature shut it up by any other 

 cover than what was capable, by its texture, of receiving 

 vibrations from sound, and by its connection with the inte- 

 rior parts, of transmitting those vibrations to the brain, the 

 use of the organ, so far as we can judge, must have been 

 entirely obstructed 



