to restore the Deaf and Dumb to hearing. 311 



quently ettiployed, no similar instance occurred : thus, demonstrating 

 on the one hand, in conjunction with other experiments, the possi- 

 bility of restoring the deaf and dumb to hearing, and on the other, 

 the great improbabihty in any given instance of so desirable an 

 event. 



In addition to the remedies above mentioned, a multitude of others 

 have long been in popular use, but with nothing to support their pre- 

 tensions. Of these, the most rational are various essences, alcohol, 

 ether, and ammonia, to which electricity and galvanism may also be 

 added ; and the least so, are preparations of earth-worms, snails, ants' 

 eggs, hog lice boiled alive, etc. 



Although the employment of stimulating means was attended with 

 so little success, a wide field for experiment yet remained, in the 

 removal of the material causes in the ear, which prevent the free 

 admission or circulation of sound. To accomplish this result, the 

 two principal operations relied upon, were the perforation of the 

 tympanum, and the injection of the Eustachian tube. The tympa- 

 num is a small cavity at the extremity of the canal which leads from 

 the auricle, or, as it is commonly called, the ear, into the head. Be- 

 tween this canal, called the meatus auditorius externus, and the tym- 

 panum, is a thin membrane, termed the membrane of the tympanum : 

 it is commonly known as the drum of the ear. Running obliquely 

 downwards from the tympanum, and opening into the pharynx or 

 back part of the mouth, is a small passage called the Eustachian 

 tube. The office of the tympanum, is to communicate sound to the 

 region of the ear wbich hes behind it. For this purpose, it is made 

 to resemble in many respects the common drum: the membrane of 

 the tympanum may be regarded as the drum-head, and the Eusta- 

 chian tube as the orifice through which air passes into the drum. 

 If now this tube be obstructed, so that no air can pass through it 

 into the tympanum ; or if the tympanum itself be filled with mucus 

 or any other material substance ; or if its membrane becomes ossi- 

 fied, or so thick that it cannot communicate the vibrations of sound, 

 the hearing will inevitably be destroyed. Such accidents often oc- 

 cur, and are a frequent source of the deafness of the deaf and dumb. 

 The two operations relied upon to accomplish a cure in these caseSy 

 will be treated of in their order. 



I. The perforation of the tympanum. — The advantage of this 

 operation may be considered as the result either of the free entrance 

 of sound, striking immediately upon the sensitive parts of the organ. 



