[ 265 J 



Received November 20., 1 77 x > 



XX. An Effay on the periodical Appearing 

 and Difappearing of certain Birds, at 

 different 'Times of the Year, In a Letter 

 from the Honourable Daines Barrington, 

 Vice-Pref. R. S. to William Watfon, 

 M. D. F. R. $. 



Dear Sir, 



Re d d M Fl1 2> 9 ' 3 °' A ^ - know, from fome convert- 

 a y J 4> i n 2 ' j-^ at j on we favQ had on this head, 



that you confider the migration of birds as a very 

 interesting point in natural hiftory, I fend you the 

 following reflections on this fubjecl: as they have oc- 

 curred to me upon looking into molt of the orni- 

 thologifts who have written on this queftion. 



It will be firft necelTary in the prsfent, as in all 

 other difputes, to define the terms on which the 

 controverfy arifes. I therefore premife that I mean 

 by the word Migration, a periodical parTage by a 

 whole fpecies of birds -acrofs a considerable extent of 

 fea. 



I do not mean therefore to deny that a bird, or 

 birds, may poflibly fly now and then from Dover to 



Vol. LXII. M m Calais, 



