46 The Jnatomj^ of a nOKSE. Chap. IV, 



may the better contribute to Hearing ; and ftrong, that it 

 may the better endure loud Sounds^ or any other external 

 Injuries ; for if once this be broke, or any way relax'd, a 

 Deafnefs mult unavoidably enfue. 



T/:>e Concha Within this Membrane there is a Cavity 



nvith the fmall ^^^^^^ the Concha^ wherein are four little 

 Bones c(fntained Bones, which are bound together by a fmall 

 in it. Ligament proceeding from the Cord of the 



Drum : The firft is called the Hammer, 

 which lies upon the fecond, called the Anvil. The third 

 is named the Stapes^ or Stirrop ; but in a Horfe it is trian- 

 gular, like the Gr£'j?i Letter A. Upon the upper Part of 

 ihe Stirrop, the longelt Fo-ot of the Anvil ftands. The 

 fourth is called Orbicular^ it is of a round Shape, and tied 

 -with a flender Ligament to the Side of the Stirrop, where 

 it is faftened to the Anvil. 



^, , jj^ Thefe Bones are a Defence to the Drum, 



-^^' and preferve it from being torn, or beat 



inwards by the violent Vibrations of the outward Air in 

 loud Sounds, and are thus aiTiiting to the Senfe of Hear- 

 ing : When the external Air beats upon the Drum, it is 

 driven againft the Hammer, which ftrikes upon tlie Anvil, 

 as the Anvil beats againft the Stirrop ; and as this Force is 

 more or lefs exerted, fo the Stirrop opens the oval Win- 

 dow more or lefs, and proportionably the Sound appears 

 louder or lower. 



^ p , The Cavities within the Os peirofunt are 



ive ^onciia. .^ Number three : The tirft, wherein thefe 

 four little Bones are fituated, is called the Concha^ from its 

 refembliiig the Shell of a Tabor. When the Membrane is 

 ftruckupon by any outward Sound, the Eccho is made in 

 this Cavity, as in a common Drum. 



There are in this Cavity divers Inftruments, whereof 

 fome arc for Puliation, as the four little Bones above-men- 

 tion'd ; fome are for conducting the Air into the other Ca- 

 vities, fuch are the two fmall Perforations, called the Win- 

 dows ; and a third fort are thofe by which the pituitous 

 Matter, collected within this Cavity, is difcharged towards 

 the Palate and Nofe. 



V:e oval Win- '^^^^ ^^^ ^^ ^^'^^^^ ^^^'° Perforations, being 

 ^^nfj^ the uppermolt and laigelt, is from its Figure 



nam'd the oval JThidoiv^ which is kept (hut 

 next the Concha^ by the Bafts of the Stirrop, as often as 

 the Sound cea fes. The other, which is rounds is always 



open. 



