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 tiU the very last 

 moment before reveaUng himself, by taking flight. This 

 alarming noise is due to the shortness and stiffness of the 

 quill, or flight-feathers. With pinions moving with incredible 

 speed, the bird is off like a rocket. Not seldom, probably, 

 it owes its hfe to this abiUty 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 gr^at 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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