430 M E M O I R S ?^/y6^ 
whilft the head of the Stapes is deprefled a little, the fuperioi' 
part of its bafis neceflarily recedes lomewhat from the fuperior 
part of the Feueflra Labyrinthiy on which it lies, and fo opens it 
a little, and as it were, ftrikes upon it : From what has been faid, 
it eafily appears that the longer tendon of the monogaftric mulclc 
of the ear contributes two ways to render hearing more eafy and 
perfed j firft as it ftretches, by the extremity of the handle of the 
JlfdlleuSt the exterior membrane of the ^ympanimy and renders 
its furface plane, or lomewhat near it, as was explained above 5 
again, as it enlarges a little its pores, fo that when the iethereal 
matter charged with the imprefTions of fonprous bodies, arrives at 
this membrane, it finds them lb dilated, that entering the cavity 
of the 'Tympanum^ it pafles eafily thro* them : As loon as it enters 
the cavity of the 7yn}panumy it gently diffufes itfelf into that 
xrthereal matter, which fills up the pores of the included air, and 
conveys the impreflions into the labyrinth by its ^orta and 
Fenefira 5 as foon as the impreffions of Ibnorous obje6ts reach the 
internal parts of the labyrinth, they there ftrike on the animal fpi- 
rits impregnated with athereal matter, and lodged within the 
various branches of the ^ortio Mollis of the ear, and thefe latter 
tranfmit their mere charader to the Centrum Ovale of the brain, 
where they excite fach ideas in the mind, as by divine appoint- 
ment they are adapted to do 5 again, the longer tendon of the 
monogaftric mufcle of the ear ferves to facilitate and perfc6t the 
fenfe of hearing, as it opens a little the fuperior part of the Fe- 
iteftra Labyr'irnhi, in the manner above explained 5 for, in the 
mean time, whilft one portion of the aethereal matter conveys the 
impreffions imparted to it by fonorous objects, and enters more 
eafily the lecond Veftibtthm of the labyrinth, another part enters 
the firft : Upon the contra6tion of the monogaftric mulcle of the 
ear, it draws a little towards itfelf, by itsfliort tendon, the head of 
the Malleus together with the Incus 5 fo that the extremity of 
the handle of the Malleus^ and the point of the internal Jlpo- 
fhyfis of the Incus are neceflarily drawn from the internal, to- 
wards the external parts of the Tympanum ; and whilft the ex- 
tremity of the handle of the Malleus is drawn from the cavity of 
the Tympanum towards the Meatus AuditoriuSy it neceflarily 
deprefles the convex part of the exterior membrane of the lym- 
fanum, to which it is connected, and thus it contributes very 
much to the increale of its natural tenfion, and to render both its 
fuperficies plane: When the acute part of the internal ^pcfhyjis 
©f the Incus is inclined from the internal towards the external 
parts of the 'Tympanum^ it neceflarily draws the head of the 
StapeS'^ 
