File:Animal locomotion, or Walking, swimming, and flying, with a dissertation on aëronautics (1874) (18171430096).jpg

Title: Animal locomotion, or Walking, swimming, and flying, with a dissertation on aëronautics
Identifier: animallocomotio00pett (find matches)
Year: 1874 (1870s)
Authors: Pettigrew, James Bell, 1834-1908
Subjects: Animal locomotion; Aeronautics
Publisher: New York, D. Appleton & company
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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Text Appearing Before Image:
158 ANIMAL LOCOMOTION. this is practically impossible, as the wing is driven with such velocity that there is positively no time to waste in waiting for the purely mechanical ascent of the wing. That the Fig. 82.
Text Appearing After Image:
Fig. 83. Figs. 82 and 83 show that when the wings are elevated (e,/, g of fig. 82) the body falls (s of fig. 82); and that when the wings are depressed (h, i, j of fig. 83) the body is elevated (r of fig. 83). Fig. 82 shows that the wings are elevated as short levers (e) until towards the termination of the up stroke, when they are gradually expanded (/, g) to i)repare them for making the down stroke. Fig 83 shows that the wings descend as long levers (h) until towards the termination of the down stroke, when they are gradually folded or flexed (i, j), to rob them of their momentum and prepare them for making the up stroke. Compare with figs. V4 and 75, p 145. By this means the air beneath the wings is vigorously seized during the down stroke, while that above it is avoided during the up stroke. The concavo-convex form of the wings and the forward travel of the body contribute to this result. The wings, it will be observed, act as a parachute both during the up and down strokes. Compare with fig. 55, p. 112. Fig. 83 shows, in addition, the com- j)Ound rotation of the wing, how it rotates upon a as a centre, with a radius m h 11, and upon a c 5 as a centre, with a radius k I. Compare with fig. 80, p. U9. —Original. ascent of the pinion is not, and ought not to be entirely due to the reaction of the air, is proved by the fact that in flying creatures (certainly in the bat and bird) there are distinct

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