160 THE NATURAL HISTORY 



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 I 

 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 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 sur- 

 face 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, 

 especially in windy weather. They breed the latest of all 

 the swallow kind : in 1772 they had nestlings on to 

 October the twenty-first, and are never without unfledged 

 young as late as Michaelmas. 



As the summer declines the congregating flocks in- 

 crease in numbers daily by the constant accession of the 

 second broods ; till at last they swarm in myriads upon 



