192 NATURAL HISTORY 
old ones attend one nest. They are often capri- 
cious 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 lay their 
eggs 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 northeast or northwest aspect, 
that the heat of the sun may not crack and destroy 
their nests; but instances are also remembered 
where they built 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 situa- 
tion; but in this neighbourhood, every summer is 
secn 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 southeast and southwest) are 
too shallow, the nests are washed down every hard 
rain ; and yet these birds drudge on to no pahoge 
from summer to summer, without changing tl 
aspect or house. It is a piteous sight to see them 
Jabouring when half their nest is washed away, and 
bringing “dirt “ generis lapsi sarcire ruinas » “Thus 
is instinct a most wonderfully uncqual faculty, in 
