C 109 ] 



the other many fpecies of foft billed birds, which 

 likewife difappear about the fame time ? The 

 following reafon may be affigned : 



" No birds are fo much on the wing as Swal- 

 lows ; none fly with fuch fwiftnefs and rapidity -, 

 none are obliged to fuch fudden and various evo- 

 lutions in their flight ; none are at fuch pains to 

 take their prey ; and we may add, none exert 

 their voice more inceflfantly ; all thefe occafion a 

 vaft expence of ftrength, and of fpirits, and may 

 give fuch a texture to the blood, that other animals 

 cannot experience ; and fo difpofe, or, we may 

 fay, neceflltate, this tribe of birds, or part of 

 them, at leaft:, to a repofe more lafliing than that 

 of any others. 



The third notion is, even at firll fight, too 

 amazing and unnatural to merit mention, if it 

 was not that fome of the learned have been cre- 

 dulous enough to deliver, for fad, what has thé 

 ftrongeft appearance of impolTibility ; we mean 

 the relation of Swallows paffing the winter im- 

 merfed undet ice, at the bottom of lakes, or 

 .^odged beneath the water of the lea at the foot 



of 



