on the Membrana Tympani. 3 



From my being connected with Mr. John Hunter's pursuits 

 in comparative anatomy, I was employed throughout the whole 

 of these dissections, and became extremely desirous of exami- 

 ning the internal parts of the ear, the structure of that organ in 

 the human body having at a very early period particularly en- 

 gaged my attention ;* but neither Dr. Hunter nor his brother 

 could be prevailed upon to sacrifice so large a portion of the 

 skull as was necessary for the purpose. 



When Mr. Corse arrived from Bengal, last year, and men- 

 tioned his having brought over a number of skulls of elephants, 

 in order to show the progress of the formation of their grind- 

 ing teeth, -f^ the desire to examine the organ of hearing in that 

 animal recurred to me so strongly, that I requested to have one 

 of the skulls for that purpose, and Mr. Corse very readily and 

 obligingly complied with my request. 



After having examined the organ in the dried skull, the want 

 of the membrana tympani, and of the small bones, made the 

 information thus received of a very unsatisfactory nature, and 

 increased the desire of seeing these parts in the recent head. In 

 considering how this could be done, I recollected a mutilated 

 elephant's head, preserved in spirits, which had been sent to 



* In the year 1776, I injected the cochlea and semicircular canals of the human ear 

 with a composition of wax and rosin. This was done by placing the temporal bone in 

 the receiver of an air pump, the upper part of which was in the form of a funnel, ren- 

 dered air-tight by a cork being fitted into its neck, and surrounded with bees' wax. 

 After the air had been exhausted, the hot injection, poured into the funnel, melted the 

 wax, and the cork was pulled out by means of a string previously attached to it ; the 

 injection immediately rushed into the receiver, and was forced, by the pressure of the 

 atmosphere, into the cavities of the temporal bone. 



f On this subject, a very ingenious paper has been since published by him, in the 

 Philosophical Transactions for the year 1799. 



B2 



