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- 
proachmg 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 m.any 
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— gerieris 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 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 
