122 The Natural History 



of Sweden and all north Europe, should want to migrate 

 from the south of Europe, and be dissatisfied with the 

 winters of Andalusia. 



It does not appear to me that much stress may be laid 

 on the difficulty and hazard that birds must run in their 

 migrations, by reason of vast oceans, cross winds, etc. ; 

 because, if we 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 remark, 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 INfcdilcrrancan : for when arrived at Gibraltar, 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. 



but scout and hurry along in little detached parties of six 

 or seven in a company ; and sweeping low, just over the 

 surface of the land and water, direct their course to the 

 opposite continent at the narrowest passage they can 

 find. They usually slope across the bay to the south- 

 west, and so pass over opposite to Tangier, which, it 

 seems, is the narrowest space. 



In former letters we have considered whether it was 

 probable that woodcocks in moon-shiny nights cross the 

 German ocean from Scandinavia. As a proof that birds 

 of less speed may pass that sea, considerable as it is, I 

 shall relate the following incident, which, though men- 

 tioned to have happened so many years ago, was strictly 

 matter of fact : — As some people were shooting in the 

 parish of Trotton, in the county of Sussex, they killed a 

 duck in that dreadful winter 1708-9, with a silver collar 

 about its neck,^ on which were engraven the arms of the 

 king of Denmark. This anecdote the rector of Trotton 

 at that time has often told to a near relation of mine ; 



^ I have read a like anecdote of a swan. 



