How should one describe the wing of a bird, as one sees 
it in flight ? 
The Dictionary, obscure and inaccurate as Dictionaries 
usually are, defines a wing as “‘ the organ of a bird, or other 
animal, or insect, by which it flies—any side-piece.” Might 
not the impression one gathers of a wing, during flight, be 
defined as of a lateral extension of the body, presenting a 
relatively large surface, but having no appreciable thickness ? 
That surface, examined in a dead bird, is seen to be formed, 
for the most part, of a series of parallel, tapering, elastic rods, 
fringed with an innumerable series of smaller, similar, but 
much shorter rods, closely packed, and linked together by 
some invisible means to form an elastic web? These we 
call the “‘ quill,” or “‘flight-feathers.”” The rest of the wing, 
and the body itself, is clothed with precisely similar structures, 
differing only in their smaller size. We call them “feathers ”’ 
commonly, without realizing that they are the ‘“‘ Hall-mark ” 
of the bird, for no other creature has ever been similarly 
clothed. 
These quill-feathers play such a tremendously important 
part in flight that their arrangement and relation to the 
underlying skeleton must be carefully examined by all who 
would understand the flight of birds. To begin with, then, 
note that they are so arranged as to overlap one another, the 
free edges of the quills facing the outer edge of the wing. 
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