262 THE COMMUNITIES OF BIRDS. 
He chooses a bamboo growing close to the water. To the branches 
of this tree he delicately suspends some vegetable fibres. He knows 
beforehand the weight of the nest, and never errs. To the threads 
he attaches, one by one (not supporting himself on anything, but 
working in the air) some sufficiently strong grasses. The task is 
long and fatiguing; it presupposes an infinite amount of patient 
courage. 
The vestibule alone is nothing less than a cylinder of twelve to 
fifteen feet, which hangs over the water, the opening being below, so 
that one enters it ascending. The upper extremity may be compared 
to a gourd or an inflated bag, like a chemist’s retort. Sometimes five 
or six hundred nests of this kind hang to a single tree. 
Such is my city of the air; not a dream and a phantasy, like that 
of Aristophanes, but actual, realized, and answering the three condi- 
tions: security both on the side of land and water, and inaccessibility 
to the robbers of the air through its narrow openings, where one can 
only enter by ascending with great difficulty. 
Now, that which was said to Columbus when he defied his guests 
to make an egg stand upright, you perhaps will say to the ingenious 
bird in reference to his suspended city. You will observe, “It was 
very simple.” To which the bird will reply, like Columbus, ‘‘ Why did 
you not discover it?” 
