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 under- 
lying 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. Only by this arrange- 
