NATURAL HISTORY OF SELBORNE. 
119 
the morning. When they fix their materials they plaster them on with 
their chins, moving their heads with a quick vibratory motion. They 
dip and wash as they fly sometimes in very hot weather, but not so 
frequently as swallows. It has been observed that martins usually 
build to a north-east or north-west aspect, that the heat of the sun may 
not crack and destroy their nests ; but instances are also remembered 
where they bred for many years in vast abundance in a hot stifled inn- 
yard against a wall facing to the south. 
Birds in general are wise in their choice of situation; but in this 
neighbourhood every summer is seen a strong proof to the contrary at 
an house without eaves in an exposed district^ where some martins 
build year by year in the corners of the windows. But, as the corners 
of these windows (which face to the south-east and south-west) are too 
shallow, the nests are washed down every hard rain ; and yet these 
birds drudge on to no purpose from summer to summer, without 
changing their aspect or house. It is a piteous 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 aflfect 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 short, and therefore they are not 
capable of such surprising turns and quick and glancing evolutions as 
the swallow. Accordingly 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 afibct sheltered districts, over 
some lake, or under some hanging wood, or in some hollow vale, 
especially in windy weather. They breed the latest of all the swallow 
kind : in 1772 they had nestlings on to October 21st, 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 appeared of late 
years in a considerable flight in this neighbourhood, 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 fortnight. 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 
