An EXPLANATION of the NINETEENTH PLATE.
The Figures in this Plate shew the Construction of the Feathers of Birds
A minute Part of a Goose's Feather
A Middle-sized Goose-Quill being examined by the naked Eye, it was easy enough to
distinguish, that the main Stem sent forth on either side about three hundred little
Arms : Those on the one side being longer and more downy ; those on the other much
more stiff and short. Many of the downy longer Arms being viewed with an ordinary
Microscope, were found each of them to have along one of its upper Edges near twelve
hundred small Branches, (if we may so call them) such as E F; and on its other Edge,
the same Number as L, I.
'Tis here proper to take notice, that each of the little Arms is of a tapering Shape from
its issuing out of the Stem to its Extremity, where it ends in a fine Point ; that it is not
a round Body, but resembles the Half of a long Cone, being concave on one side, and
on the other convex, its Breadth making an acute Angle with the Length of the Stem ;
That the middle or most convex Part is fine and membranous, its Under-Edge being an
extremely smooth and thin Film ; but the upper and outer Edge ends flat, and thereby
forms two other bairy Edges, each having a different Sort of Hairs, laminated, or some-
what broad at Bottom, but slender and bearded upwards.—Note, The Concavity of the
Arms makes them readily fall into one another.
The flat upper Edge, and the two Edges made thereby, are shewn by a transverse Sec-
tion I N O E, and the two Kinds of Hairs or little Branches by E F, L I.
Each of the Branches E F seemed to have sixteen or eighteen Joints, out of which
small long Fibres or Tendrils issued, gradually longer or shorter than one another, ac-
cording to their Position along the Branch E F ; those on the Under-side, viz. 1, 2, 3,
4, 5, 6, 7, 8, 9, &c. being much longer than those directly against them on the Up-
per, and several of them as 3, 4, 5, 6, 7, 8, 9, were terminated with such small Hooks,
as are visible to the naked Eye on the Seed-Buttons of the Bur-dock.
The Fibres on the other Edge L I appeared with near as many knotted Joints, but
without any Tendrils or Hooks, each of them about the Middle K seeming to divide into
a Kind of Fork ; one Part whereof, namely K L, was nearly the same Length as K I ;
the other M was very short.
PLATE XIX. FIG. 2.
Two Parts of a Goose's Quill
THE wonderful Structure of the Parts just now described, deserves the most serious
Attention and Consideration as to their Use : In order to explain which the more
readily, the Figure under our Eye was given.
We see here two Pieces of the downy Arms I N, E O, placed, as to one another, in
the same manner as they appear upon the Quill, at the Distance of I F, or somewhat
more. The collateral Branches a a a a, b b b b, are so ranged that they lie upon and
cross over one another ; by which means the hooked Ends of the Tendrils on the
Branches of one Arm, getting between the naked Branches of the Arm next to them,
which are full of Knots, the Hooks of the Tendrils clasp round those Knots, and fasten
all the Parts so closely and admirably together, as to hinder even the Air from passing
through them. And though the Thickness of one of these Tendrils amounts not to the
five hundredth Part of an Inch, they all together form so strong a Texture, that the ex-
quick and violent beating of them against the Air by the Strength of the Bird's
Wing, is unable to disjoin them.
The Contrivance and Fabrick of the numberless little Parts which constitute a Feather,
taken either separately or together, strongly prove the Wisdom of Providence, and its Care
of all its Creatures, even in the minutest Matters ; for their Contexture is such, that if
the component Parts should be violently disjoined by any external Injury, (several of
which Separations would prevent the Bird from flying) they for the most part, by a