. Animal locomotion or walking, swimming, and flying : with a dissertation on aëronautics. Thisit does by rotating on its long axis, and in virtue of its flexi-bility and elasticity, aided by the recoil obtained from theair. In other words, it is not necessary to elevate the wingforcibly in the direction c d to obtain the upward and forwardmovement c e. One single impulse communicated at a causesthe wing to travel to e, and a second impulse communicatedat e causes it to travel to i. It follows from this that a seriesof vigorous down impulses would, if a certain interval wereallowed to elapse b
. Animal locomotion or walking, swimming, and flying : with a dissertation on aëronautics. Thisit does by rotating on its long axis, and in virtue of its flexi-bility and elasticity, aided by the recoil obtained from theair. In other words, it is not necessary to elevate the wingforcibly in the direction c d to obtain the upward and forwardmovement c e. One single impulse communicated at a causesthe wing to travel to e, and a second impulse communicatedat e causes it to travel to i. It follows from this that a seriesof vigorous down impulses would, if a certain interval wereallowed to elapse between them, beget a corresponding series ofup impulses, in accordance with the law of action and re-action; the wing and the air under these circumstances beingalternately active and passive. I say if a certain intervalwere allowed to elapse between every two down strokes, but 158 ANIMAL LOCOMOTION. this is practically impossible, as the wing is driven with suchvelocity that there is positively no time to waste in waitingfor the purely mechanical ascent of the wing. That the Fig. S3. Figs. 82 and 83 show that when the wings are elevated (e, f, g of fig. 82) thebody falls (s of fig. 82) ; and that when the wings are depressed (It, l,j offig. 83) the body is elevated (r of fig. S3). Fig. 82 shows that the wings areelevated as short levers (c) until towards the termination of the up stroke,when they are gradually expanded (/, g) to prepare them for making thedown stroke. Fig. S3 shows that the wings descend as long levers (h untiltowards the termination of the down stroke, when they are gradually foldedor flexed (i, j), to rob them of their momentum and prepare them for makingthe up stroke. Compare with figs. 74 and 75, p. 145. By this means the airbeneath the wings is vigorously seized during the down stroke, while thatabove it is avoided during the up stroke. The concavo-convex form of thewings and the forward travel of the body contribute to this result. Thewings,
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Keywords: ., bookcentury1800, bookdecade1870, booksubje, booksubjectphysiology
