106 
MIGRATION AND FLIGHT. 
that these birds had quitted the British shores about 
an hour before dawn, they would naturally have 
arrived at the point where they were thus seen 
landing: others probably had come in before, as in 
the course of the morning we saw, on the roof of a 
large building in the town, which was exposed to 
the full force of the sun’s rays, an infinitely greater 
number of Swallows collected together than we had 
observed throughout the whole of the season. 
That this is the practice of many other birds, 
indeed, is well known, particularly of those which are 
in the habit of feeding at night. In the fen countries, 
for instance, which, on account of their ditches and 
marshes, are favourite haunts for water-birds, in 
almost every still night, more especially about the 
time of their usual journeys, either to or from the 
fens, the whistling sound of thousands of wings, or 
the shrill notes of call, by which these vast flights 
are kept together in the darkness of night, may be 
heard over head. 
Birds, too, in their longer flights, no doubt avail 
themselves of different currents in the air ; for we 
know that often, when the lower stream of air is 
blowing from the west, another stream, far above, 
may be blowing from another direction; this maybe 
frequently seen by the motion of the upper clouds 
moving in contrary directions from those at a lower 
level. Those most beautiful of all the feathered 
race, the birds of Paradise, (not only distinguished 
by their brilliant plumage, but from their being 
singularly decorated with tufts or trains of light 
loose fringy feathers, which render it difficult for 
them to fly, excepting against the wind, which 
