( 887 ) 
the Meatus patulent, open (fcarfe being guarded by the 
Cartilage) and ftreight, w hofe length (it reaching from 
the external to the internal Table of the Scull) ia fuffi- 
dent to prevent the accelTion of too ^reat a quantity of 
Air to the Tympafiuw, for in its progrefs moft of the Ctf- 
lumna Aeris beat againft one or other of the fides of the 
Meatus, in fomuch that their force is inhibited, and on- 
ly fo many as fulEce to convey the Sound, can' reach 
the Tympanum it felf. 
The Meatus Auditorius then is a long 
ftreight Tube or Canute fituated Horizontal- 
ly, and reaching from the outer to the in- 
ner Table of the Scull, in Figure not unlike the Barrel 
of a Piflol, but fomevvhat Oval, the fides of whofe Ca- 
vity are hard and folid, about the thicknefs of a Half- 
penny, from whofe outer Part feveral of the Lamina be- 
twixt the two Tables of the Scull do arife, (Fig, T.) hs 
Cavity is an Inch or ^ of an Inch Diameter, and length 
9 f Inches ; being fomewhat enlarg’d as it arrives at the 
Crena for the Memhrana Tympani, (Fig, II.) 
This Crena is two Inches in Circumfe- 
rence, within which is the Cavitas Tym^ 
pans, confifting of two different Surfaces ; 
the one much deeper and Cellulous, the other more 
fuperficial and Smooth. The firfl runs perpendicular- 
ly down ~ Inch from the Crena Tympani, Its bottom is 
varioufly divided into feveral Celluls, not unlike a 
Hony Comb, but irregularly difpos’d. Its Bony Lami- 
rj£, by which thefe Cellules are diftinguifh’d from each 
other, are thicker at the Top than at the Bottom, they 
being one Line, two Lines, or i - Line diftant from each 
other, and about \ Inch deep. Could I have got it fo 
well cleans’d as I wifli’d for, doubtlefs I might have 
obferv’d their Communication with each other, by means 
of certain Orifices which ferve to convey what fuper- 
Y y y y y y fluous 
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