SWALLOWS' NESTING PLACES. 155 



nurses, congregate in great flocks, and are the birds that are 

 seen clustering and hovering on sunny mornings and evenings 

 round towers and steeples, and on the roofs of churches and 

 houses. These congregatings usually begin to take place about 

 the first week in August ; and therefore we may conclude that 

 by that time the first flight is pretty well over. The young of 

 this species do not quit their abodes all together ; but the more 

 forward birds get abroad some days before the rest. These ap- 

 proaching the eaves of buildings, and playing about before them, 

 make people think that several old ones attend one nest. They 

 are often capricious in fixing on a nesting-place, beginning many 

 edifices, and leaving them unfinished ; but when once a nest is 

 completed in a sheltered place, it serves for several seasons. 

 Those which breed in a ready finished house get the start in 

 hatching of those that build new by ten days or a fortnight. 

 These industrious artificers are at their labours in the long days 

 before four in 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 a 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 in- 

 stances 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 



