because I've eaten chickens' wings."

"Why didn't you say, Dodo, because there has to be something for the
feathers to stick into?" said Nat decidedly.

"You both have very good reasons," said the Doctor. "The plumage of the
wings grows out from the skin, just as feathers grow from any other part
of the body, only the large ones are fastened to the bones, so that they
stay tight in their proper places. If they were loose, they would fly up
when the bird beats the air with its wings, and get out of order. See
how smoothly they lie one over another! When the bird closes its wings,
they come together snugly along its sides. But when the wing is spread,
they slide apart--yet not too far to form a broad, flat surface, quite
stiff, but light and elastic. By beating the air with the wings birds
fly along. It is something like rowing a boat. This surface pushes
against the air as the flat blade of an oar pushes against the water.
That is why these large stiff feathers are called the rowers. When the
Wise Men talk Latin among themselves, they say _remiges_, for 'remiges'
means rowers."

"But, Doctor," said Rap, who was looking sharply at the Sparrow's wing,
"all the feathers are not like that. Here are a lot of little ones, in
rows on top of the wing in front, and more like them underneath,
covering over the roots of the rowing feathers. Have they any name?"

"Oh, yes! Everything you can see about a bird has its own name. Those
small feathers are called _coverts_, because they cover over the roots
of the rowers. Those on top are the upper coverts; those underneath are
the under coverts, or lining of the wings. Now notice those two pretty
bands of color across the Sparrow's wing. You see one band is formed by
the tips of the longest coverts, and the other band by the tips of the
next longest coverts. Those two rows of feathers are the greater and
middle coverts, and all the smallest feathers, next to the front edge of
the wing, are called lesser coverts. Now look at the tail, Rap, and tell
me what you can find."

"Why, there is a bunch of long stiff feathers like rowers, that slide
over each other when you spread the tail, and a lot of short feathers
that hide the roots of the long ones. Are they rowers and coverts too?"
"A bird does not row with his tail--he steers with it, as if it were a
rudder; and the long feathers are therefore called rudder-feathers--or
_rectrices_, which is Latin for rudders. But the short ones are ca