PHYSICAL AND LITERARY. 277 



proving the non-exiftence of air in this place. 

 Such are the following ; 



I. Dissect the teguments and intercoftal 

 mufcles from the pleura of either a dead 

 man or quadruped without wounding this 

 membrane, in which there is no difficulty j 

 then pull up and deprefs alternately the Jier- 

 num and ribs as often as you will, the lungs 

 are feen contiguous all the while to the 

 pleura; but, on making a fmall puncture 

 thro' this membrane, the lungs, if they are 

 not grown to the pleura, which is often the 

 cafe in the human fubjedt, fly from the 

 pleura, and are no more feen. :. ,- 



2. This connexion of the lungs and 

 pleura, more or lefs of which is feen in moil 

 human bodies, implies flrongly a natural 

 contiguity of thefe two parts. 



3. Lay bare the pleura, without wound- 

 ing it, between two ribs of any living quadru- 

 ped, which requires no great dexterity ; and 

 then the contiguity of the lungs and pleura 

 may be feen, tho' the lungs are conftantiy 

 Aiding and changing place along the pleura, 

 and tho' this membrane is in different ftates : 

 Mobile the creature infpires, it is concave; 



dufipff 



