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NATURAL HISTORY. 



Observations on the Effects ivhich 

 lake Placefrom ike Destruction of 

 the Memhrana Ti/mpani of the 

 Ear. By Mr. Astleij Cooper, in 

 a Letter to Evei'ard Home, Esq. 

 with some additional Remarks on 

 the Mode of Hearing in such 

 Cases, hj Mr. Home ; from the 

 Philosophical Transactions for 

 1800. 



Dear sir, 



AT the time you were engaged 

 in the investigation of the 

 structure and uses of the membrana 

 tympani) you mentioned a wish to 

 ascertain the effect a rupture of that 

 membrane would have upon hear- 

 ing. I now send you some obser- 

 vations on that subject, which, if 

 you think them of sufficient impor- 

 tance, you will do me the honour of 

 presenting to the Royal Society. 

 I am, &c. 



Astley Cooper. 



Anatomists have endeavoured to 

 ascertain, by experiments on quad- 

 rupeds, the loss of power which the 

 organ of hearing would sustain by 

 perforating themembrana tijmpani: 

 dogs have been made the subject of 

 these trials ; but the results have 

 been neither clear nor satisfactory, 

 and they accord but. little with 

 the phaenomena I am about to re- 

 late. 



Mr. Cheselden had couceived ihc 



design of making the human organ 

 itself the subject of direct experi- 

 ment; and a condemned criminal 

 was pardoned, on condition of his 

 submitting to it ; but, a popular 

 outcry being raised, it was thought 

 proper to relinquish the idea. 



Though denied the aid of experi- 

 ment, we are not without the 

 means of obtaining knowledge upon 

 such subjects; since the changes, 

 produced by disease, frequently 

 furnish a clue which is equally satis- 

 factory. 



It often happens, that some parts 

 of an organ are destroyed by dis- 

 ease, whilst others are left in their 

 natural state ; and hence, by the 

 powers retained by such organ, after 

 a partial destruction, we are en- 

 abled to judge of the functions per- 

 formed by those parts, when the 

 whole was in health. 



Guided by this principle, I have 

 made the human ear the subject of 

 observation, and have endeavoured 

 to ascertain the degree of loss it sus- 

 tains in its powers by the want of the 

 membrana tijmpani; a membrane 

 which has been generally consider- 

 ed, from its situation in the meatus, 

 and its connection with the adjacent 

 parts, by a beautiful and delicate 

 structure, as essentially necessary to 

 the sense of hearing ; but which, as 

 appears by the following observa- 

 tions, may be lost, with little pre- 



