160 NATURAL HISTORY OF SELBORNE. 



sight to see them labouring when half their nest is washed away and 

 bringing dirt .... "generis lapsi sarcire ruinas." Thus is instinct 

 a most wonderful unequal faculty ; in some instances so much above 

 reason, in other respects so far below it ! Martins love to frequent 

 towns, especially if there are great lakes and rivers at hand ; nay 

 they even affect the close air of London. And I have not only seen 

 them nesting in the Borough, but even in the Strand and Fleet 

 Street ; but then it was obvious from the dinginess of their aspect 

 that their feathers partook of the filth of that sooty atmosphere. 

 Martins are by far the least agile of the four species ; their wings and 

 tails are shorthand therefore they are not capable of such surprising 

 turns and quick and glancing evolutions as the swallow. Accord- 

 ingly they make use of a placid easy motion in a middle region of 

 the air, seldom mounting to any great height, and never sweeping 

 long together over the surface of the ground or water. They do 

 not wander far for food, but affect sheltered districts, over some 

 lake, or under some hanging wood, or in some hollow vale, espe- 

 cially in windy weather. They breed the latest of all the swallow 

 kind : in 1772 they had been nestlings on to October 2ist, and are 

 never without unfledged young as late as Michaelmas. 



As the summer declines the congregating flocks increase in 

 numbers daily by the constant accession of the second broods ; till 

 at last they swarm in myriads upon myriads round the villages on 

 the Thames, darkening the face of the sky as they frequent the aits 

 of that river, where they roost. They retire, the bulk of them I 

 mean, in vast flocks together about the beginning of October ; but 

 have appsared of late years in a considerable flight in this neigh- 

 bourhood, for one day or two, as late as November the 3rd and 6th. 

 after they were supposed to have been gone for more than a fort- 

 night. They therefore withdraw with us the latest of any species. 

 Unless these birds are very short-lived indeed, or unless they do not 

 return to the district where they are bred, they must undergo vast 

 devastations somehow, and somewhere ; for the birds that return 

 yearly bear no manner of proportion to the birds that retire. 



House-martins are distinguished from their congeners by having 

 their legs covered with soft downy feathers down to their toes.* 

 They are no songsters ; but twitter in a pretty inward soft manner 

 in their nests. During the time of breeding they are often greatly 

 molested with fleas. I am, &c. 



* And a separate genus has been made for it in consequence, which is adopted by some 

 Tnithologists. 



