These general principles once realized, a foundation is 
laid on which one may base observations on the peculiarities 
of flight distinguishing different types of birds. 
Most of us, probably, at one time or another, in taking a 
walk through the woods, have been startled, almost out of 
¢ 
our wits, by a sudden “ whirr”’ of wings at our very feet ; 
made by some crouching pheasant, waiting till the very last 
moment before revealing himself, by taking flight. This 
alarming noise is due to the shortness and stiffness of the 
quill, cr flight-feathers. With pinions moving with incredible 
speed, the bird is off like a rocket. Not seldom, probably, 
it owes its life to this ability to disconcert its enemies, till it 
has put a safe distance between itself and danger. By way 
of contrast, let us take the absolutely silent, easy movements 
of the owl, stealing forth in the twilight of a summer’s evening, 
seeking whom he may devour. Here, again, we have a 
meaning in the mode of flight. Here silence is more than 
golden: it means life itself. Nimble-footed, sharp-eared 
mice and rats, must be snatched up before even the breath 
of suspicion can reach them. The uncanny silence of this 
approach is rendered possible only by what may be called a 
“ muffling’’ of the wings. For the flight-feathers are not 
only of great breadth, but they are covered, as it were, with 
velvet-pile, the ‘‘ barbules”’ of the wing-quills, which form 
the agents by which the “‘ web”’ of the quill is held together, 
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