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theatres are more deceptive than more finifh- 

 cd works ; but this proceeds from the diftance 

 and lamp light in which we view them. 



It is obfervable, that there are birds pecu* 

 liar to fome particular trads of land, which 

 will not propagate or fpread themfelves into 

 other countries, though in the fame latitude, 

 and on the fame ifland, by which they might 

 very eafily extend themfelves, if one particular 

 place had not fomething in it, unknown to us, 

 which caufes them to continue where they are. 

 To inftance one amongft many, by way of ex- 

 ample : the Cornijh Chough ^ or Coracias of Al- 

 firovand^ is faid ,by Mr. WtUoughby^ in his Or- 

 nithology, to breed on the clefts and rocks of 

 Cornwal, and on the coafts of Wales, and all 

 the weftern côafts of England. Yet I cannot 

 learn that there are any of them on the fouthern 

 coafts of England to the eaftward of Devon- 

 fliire, nor on any part of the eaftern coafts 5 

 though thefe are in parallel latitudes to the 

 weftern coafts where thefe birds abound, and 

 the coafts in many places have clefts and rockg 



feem- 



