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I. And most visible Thing, is the Shape, and Make of theif Body, not thick and clumsy, but incomparably adapted to their Flight: Sharp before, to pierce and make Way through the Air, and then by gentle Degrees rising to its full Bulk. To which we may add, 1

II. The neat Position of the Feathers throughout the Body; not ruffled, or difeompos'd, or plac'd some this, some a contrary Way, according to the Method of Chance; but all artificially plac'd (a), for facilitating the Motion of the Body, and its Security at the fame Time, by way of Cloathing: And for that End, most of the Feathers tend backward, and are laid over one another in exact and regular Method, armed with warm and soft Down next the Body, and more strongly made, and curiously clos'd next the Air and Weather, to fence off the Injuries thereof. To which Purpose, as also for the more easy and nimble gliding of the Body through the Air, the Provision Nature hath made, and the Instinct of these Animals to preen and dress their Feathers, is admirable; both in respect of their Art and Curiosity in doing it, and the Oyl-bag (Æ), Glands, and whole Apparatus for that Service.

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{a) See before Book IV. Chap. it. Note (I).

(b) Mr. Willughby faith, there are two Glands for the Secretion of the unctuous Matter in the Oyl-bag. And so they appear to be in Geese. But upon Examination, I find, that in most other Birds, (such at least as 1 have enquir'd into,) there is only one Gland: In which are divers little Cells, ending in two or three larger Cells, lying under the Nipple of the Oyl-bag. This Nipple is perforated, and being pressed, or drawn by the Bird's Bill, or Head, emits the liquid Oyl, as it is in some Birds, or thicker unctuous Grease, as it is in others. The whole Oyl-bag is in its structure somewhat conformable to the Breasts of such Animals as afford Milk. > . .' ■ -. .'.•■.:• ail L -..

III. And

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upon the Air. i. A yet lesser Nicety is observ'd, and that is, in the very sloping the Tips ot' the Flag-feathers: The interiour Vanes being neatly flop'd away to a Point, towards the outward Fart of the Wing; and the exteriour Vanes slop'd towards the Body, at least in many Birds; and in the Middle of the Wing, the Vanes being equal, are but little flop'd. So that the Wing, whether extended or shut, is as neatly flop'd and form'd, as if constantly trimm'd with a Pair of Scissors.

(e) Since no exact Account that I know of, hath been given of the Mechanism of the Vines, 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 Lamina, which are thin, stiff, and somewhat of the Nature of a thin Quill. Towards the Shaft of the Feather, (especially in the Flagfeathers of the Wing,) those Lamina are broad, vc. of a semicircular Form; which serve for Strength, and for the closer snutting of the Lamina to one another, when Impulses are made upon the Air. Towards the outer Part of the Vane, these Lamina grow slender and taper: Oh their tn-" der 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 Lamina 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 Lamina, have strait Beards, as in Fig. 19. those on the other Side, have hook'd Beards on one Side the slender Part «f the Bristle, and strait ones on the other, as in Fig. 10. Both these Sorts of Bristles magnify'd, (only scattering, and not close,) are represented as they grow upon the upper Edge of the Lamina f. 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 Lamina 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 redue'd and repair'd. Vid. Book IV. Chap. 11. Xott im).

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(/) Peftorales Mttsculi Hominls fteclentes humeros, parvi &parum carnofi funs; non tqttant $oam ant 70am partem omnium Mufiulorum Hominis. E contra in Avibus, Pejorates Mufiuli vaftijpmi funt, v iquant, imo excedunt, er magis pendent, quam reliqui omnes Mufiuli ejufdem Avis simul sumpti. Borcll. de Mot. Animal. Vol. I. Prop. 184.

Mr. Willughby having made the like Observation, hath this Reflection on it, whence, if it be possible for Man to fly, it is thought by them who have curiously weighed and considered the matter, that he that would attempt such a Thing with Hopes of Success, must so contrive and adapt his Wings, that he may make use of his Legs, and not his Arms in managing them: (because the Muscles of the Legs are stronger, as he observes.) Willogh, Ornith. L. 1. c. 1. J, 10.

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scents in the Air, as also serving to steady (£) Flight, by keeping the Body upright in that subtile and yielding Medium, by its readily turning aud answering every Vacillation of the Bodyw06

And now to the Parts serving to Flight, let usadd the nice and compleat Manner of its Performance j all done according to the strictest Rules of Mechanism (&). What Rower on the Waters, wbac A^ tist on the Land, what acutcst Mathematician qould give a more agreeable and exact Motion $o the Wings, than these untaugbt flying Artists do . theirs! Serving not only to bear their Bodies up in the Air, but also to waft them along therein, with a speedy progressive Motion, as also to steer and turn them this Way and that Way, up and down, faster or flower, as their Occasions require, or their Pleasure leads them.

V. Next to the Parts for Flight, let us view the Feet and Legs ministering to their other Motion: Both made light, for easier Traosportationthrough the Air* and the former spread, some with Membranes for Swimming (i), some without, for steady

Going,

(g) Mr. Willugbby, Ræj, and many others, imagine the principal use of the Tail to be to steer, and turn the Body in the Air, as a Rudder. But Bordli hath put it beyond all doubt, that this is the least use of it, and that it is chiefly to adist the Bird in its Ascents and Descents in the Air, and to obviate the Vacillations of the Body and Wings. For as for turning to this or that Side, it is performed by the Wings and Inclination of the Body, and but very little by the help of the Tail.

(h) See Btnelli *bt supr. Prop. 181, cc. .,5fiT xhityt (1) It is considerable in all Water-Fowl, how exactly their Legs and Feet correspond to that way of Life. For either their Legs are long, to enable them to wade in the Waters: In which cafe, their Legs are bare of Feathers a gqod, way above the Knees, the more conveniently for this Purpose. Their Toes also are all abroad; and in such as bear the t„ ■ - _ "'Name

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