236 NATURAL HISTORY 



and such hardy birds as are known to defy 

 all the severity of Eughnuf, and even of 

 Sweden and all north Europe, should want 

 to migrate from the south of Europe, and 

 be dissatisfied with tlieWinters of ^ ndalusia. 

 It does not appear to me that much stress 

 may be laid on the difficulty and hazard 

 that birds mus-t run in their migrations, by 

 reason of vast oceans, cross winds, &c. ; be- 

 cause, if w^e reflect, a bird may travel from 

 England to the equator without launching 

 out and exposing itself to boundless seas, 

 and that by crossing the water at Dover, 

 and again at Gibraltar. And I with the 

 more confidence advance this obvious re- 

 mark, because my brother has always found 

 that some of his birds, and particularly the 

 swallow kind, are very sparing of their 

 pains in crossing the Mediterranean : for 

 when arrived ViVGibraltar, they do not 



" Rang'd in figure wedge their way, 

 " And set forth 



" Their airy caravan high over seas 



" Flying, and over lands with mutual wing 



" Easing their flight:" Milton. 



