I take next, the profile of my feather (B, Fig. 1), and find that it is
twisted as the sail of a windmill is, but more distinctly, so that you
can always see the upper surface of the feather at its root, and the
under at its end. Every primary wing-feather, in the fine flyers, is
thus twisted; and is best described as a sail striking with the power
of a cimeter, but with the flat instead of the edge.

[Illustration: FIG. 1.]

(Twice the size of reality.)

A

_a_ 1

_a_ 2

B]

32. Further, you remember that on the edges of the broad side of
feathers you find always a series of undulations, irregularly sequent,
and lapping over each other like waves on sand. You might at first
imagine that this appearance was owing to a slight ruffling or disorder
of the filaments; but it is entirely normal, and, I doubt not, so
constructed, in order to insure a redundance of material in the plume,
so that no accident or pressure from wind may leave a gap anywhere. How
this redundance is obtained you will see in a moment by bending any
feather the wrong way. Bend, for instance, this plume, B, Fig. 2, into
the reversed curve, A, Fig. 2; then all the filaments of the plume
become perfectly even, and there are no waves at the edge. But let the
plume return into its proper form, B, and the tissue being now
contracted into a smaller space, the edge waves are formed in it
instantly.

[Illustration: FIG. 2.

A

B]

Hitherto, I have been speaking only of the filaments arranged for the
strength and continuity of the energetic plume; they are entirely
different when they are set together for decoration instead of force.
After the feather of the robin's wing, let us examine one from his
breast.

33. I said, just now, he might be at once outshone by a brickbat.
Indeed, the day before yesterday, sleeping at Lichfield, and seeing,
the first thing when I woke in the morning, (for I never put down the
blinds of my bedroom windows,) the not uncommon sight in an English
country town of an entire house-front of very neat, and very flat, and
very red bricks, with very exactly squared square windows in it; and
not feeling myself in anywise gratified or improved by the spectacle, I
was thinking how in this, as in all other good, the too much destroyed
all. The breadth of a robin's breast in brick-red is delicious, but a
whole house-front of brick-red as vivid, is alarming. And yet one
cannot generalize even that trite moral with any safety--