Note Book VII. Chap. 1. Note (e) — BOOK VII.

[e] Since no exact Account that I know of, hath been given of the Mechanism of the Vanes, or Webs of the Feathers, my Observations may not be unacceptable. The Vane consists not of one continu’d Membrane; because if one broken, it would hardly be reparable: But of many Laminæ, which are thin, stiff, and somewhat of the Nature of a thin Quill. Towards the Shaft of the Feather, (especially in the Flag-feathers of the Wing,) those Laminæ are broad, &c. of a semicircular Form; which serve for Strength, and for the closer shutting of the Laminæ to one another, when Impulses are made upon the Air. Towards the outer Part of the Vane, those Laminæ grow slender and taper: On their under Side they are thin and smooth, but their upper outer Edge is parted into two hairy Edges, each Side having a different Sort of Hairs, laminated or broad at Bottom, and slender and bearded above the other half. I have, as well as I could, represented the uppermost Edge of one of these Laminæ in Fig. 18. with some of the Hairs on each Side, magnify’d with a Microscope. These bearded Bristles, or Hairs, on one Side the Laminæ, have strait Beards, as in Fig. 19. those on the other Side, have hook’d Beards on one Side the slender Part of the Bristle, and strait ones on the other, as in Fig. 20. Both these Sorts of Bristles magnify’d, (only scattering, and not close,) are represented as they grow upon the upper Edge of the Lamina s. t. in Fig. 18. And in the Vane, the hook’d Beards of one Lamina, always lie next the strait Beards of the next Lamina; and by that Means lock and hold each other; and by a pretty Mechanism, brace the Laminæ close to one another. And if at any Time the Vane happens to be ruffled and discompos’d, it can by this pretty easy Mechanism, be reduc’d and repair’d. Vid. Book IV. Chap. 12. Note (m).