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Show 0/ the Phi/‘13 of. 731% r. Chap. XX. the Air immediately infinuarcrh it felf into the Cavities lodged under the \Ving, wherein it being compreifed, is rendred more thick and Globular in the inferior and concave part of the \Ving; whereupon the body 'of the CHAP} XXL Bird, rolling upon the Air, which being beaten backward, {hooteth it forward, and {gaineth place after place fucceflively. The nines are lztytrxtleL‘II Ill their motion, both up" artl and downwai d. 0/ the Flying of Iii/effro And in both poftures of Elevation and Depreflion of the Wings, they are always kept Extended, elfe the Birds could not be deteined Swimming in the Air, but would be immediately forced by its "eight toward the Center. In fine, it's mofi agreeable, that Birds in the different pofitions of their Bodies in order to Flying, are conduéicd by their \Vings, as by Oars, and by their Tails as Ruddets; and according to greater or lefs Vibrations of both Wings, equally moving are carried forward, or Latcrally by one \Ning moving briskly, and the other Facintly, or upward, by the motion of the Wings and Tail, which do conftitute mofi, if not all, the kinds of iimple, mixed, and circular motions of Flyin . To conclude our Difcourfe of this Subject, and to fpeak fomewhat more clearly of it : Birds foar upward by the help of both Wings, equally and lirongly beating the Air, and by the Tail, forcing it felf potently down- ward, which mounteth up the body of Birds, and they move downward as prefled by their own Weight, balanced by the gentle Expanfions of their Wings, fomewhat tending toward Flexion; and are carried forward by the appulfes of both Wings moving downward, and fomewhat backward upon the Air ( thickned by frequent Compreflions ) by whofe refifiance the body of Birds is darted forward: and Birds are afied with oblique Motions, tending to each fide, caufed by the unequal force of the Wings, one making weak, and the other flrong Vibrations, upon the Condenfed Air: And in Circular Motion, where there is a Circumvolution of the Body in order to a Retrograde Flight, it is managed by a ftrong and brisk Motion of one Wing, and by the aflif'tance of the Tail as a Rudder, whereupon the body of Birds is turned round, to a mofi oppofite Point; and afterward is carried forward by both Wings, making equal repeated firoaks upon the thickned Conglobated Air, Propelled downward, and backward, by whofe Renitence and Impulfe, the body of Birds encircled with a light Feathered Robe, is forced forward from place to place. A He wings of Infeé'ts ( by which their Progreflivc Motion is accom‘. T plilhed) are full of Beauty and Wonder, fpeaking the great Conn, trivance of the Omnipotent Agent, as being graceful Objects, adorned with variety of Colours, interfperfed with fmall Specks, and Cells, and mofl admirable in their curious Contextures, as being compofed of fine , . Films, Dreffed with manifold Fibrils, feared in divers Ranks, one above fifé‘slfid another, and running in divers Poiitions, to give different Motions back~ d'cmdwirh many rows of ward and forward, to thefe rare Machines; which take their firfl rife in Fmrilsfluccd the Thorax, beyond the center of Gravity, toward the Head, and this 335,33," E\Centrick Polition of the wings, is finely balanced by the Expanded Area of the Wings, which are lodged backward, toward the Extreamitics of Flies This choice Compofition of Wings of Flies, and other lnfeéts, confif't- fil‘fi'gffi" eth of thin Membranes, covered with fine Feathers, or Down, beautified g::";:j,,j;,§ with various Colours, and accommodated with all forts of Veifels fit for orDowr-r Life and Motion; the laft of which is celebrated by various Ranks, of curious Mufcles and Fibrils, feared in the upper and loWer Region of the Wings, as fo many Abduétors, and Adduéiors, Elevators, and Depreffors, drawing them up and down with equal quieknefs, productive of nimble Flight in thefe pretty Creatures : So that the Motion of the wings is fainter or brisket, to make lefs or greater halt according to pleafure, and the utA molt extent of the Motion of them, is :16th above a little beyond the Back, and below beyond the Belly. And I conceive, the wings being {trained by vertue of their Fibres, to the ntrnoft firech in the height of their Motion, are alr‘noft brought to a Plain, only the fore part is lowred a little, and the wings being modelled after this manner, and brought to a lower pitch; their hinder part is carried with fomewlmt a‘greater quicknefs then their former, and the Area 'of the wings doth fomewhat dip behind (according to ingenious Mr. Hook) and after the fame manner they feem to be carried back again inarjuick Motion, to their firl'i Pofltion, and the Area is lowred, as they tend backward, be; eaufe the Fibres making a greater Contraction, do caufe a greater Vibration of the fame Stem, which fringeththe Wing. , _ . , And thefe Vibrations aéled with greatVeloeity, are produced by nimble Contractions of Antagonill Mufcles, the Abdtiétors, and Adduétors, lodged in the wings, which move with fomuch Dexterity and Qiicknefs, that they feem to refemble the moli nimble Vibrations of the Mufical Strings, which being hichly iireched, do make numerous motions. in a Minute. , Thus having given fome Preliminary Account of the Structure and various Vibrations of the wings of Infeéts, with your leave, I {hall now endear-- tour to fpeak my Thoughts, how the flight of Infeéts is performed, which being light Bodies, and pendulous in the Air, are fupported by their Ex~~ handed wings, relting iipon many Columns of a Fluid Body, of an Elafliclr nature; which being highly Vibrated by repeated Rroaks, do give the ads, . vantage ,, , $533513? 31355,,"ET! $531333" I: |