ARCHITECTURE OF BIRDS. 261 
will spy his opportunity, and go off the richer for a thread or 
two. 
Collections of nests are very recent, not numerous, and, as yet, 
not rich. In that of Rouen, however, which is remarkable for its 
arrangement ; in that of Paris, where many very curious specimens 
may be examined; you can distinguish already the different industries 
which create this master-piece of the nest. What is the chronology, 
the gradual growth of it? Not from one art to another (not from 
masonry to weaving, for example) ; but in each separate art, the birds 
which abandon themselves to it are more or less successful, according 
to the intelligence of the species, the abundance of material, or the 
exigency of climate. 
Among the burrowing birds, the booby, and the penguin, whose 
young, as soon as born, spring into the sea, content themselves with 
hollowing out a rude hole. But the bee-eater, the sea-swallow, which 
must educate their young, excavate under the ground a dwelling which 
is admirably proportioned, and not without some geometrical design. 
They furnish it, moreover, and strew it with soft yielding substances 
on which the fledgling will be less sensitive to the hardness or freshness 
of the humid soil. 
Among the building-birds, the flamingo, which raises a pyramid of 
mud to isolate her eggs from the inundated earth, and, while standing 
erect, hatches them under her long legs, is contented with a rude, 
