. Animal locomotion, or Walking, swimming, and flying, with a dissertation on aëronautics. Animal locomotion; Aeronautics. 160 AKIMAL LOCOMOTION. and as a consequence likewise of the speed at which the insect is travelling, the wings during the back stroke are for the most part actually travelling forwards. This is accounted for by the fact, that the body falls downwards and forwards in a curve during the up or return stroke of the wings, and be- cause the horizontal speed attained by the body is as a rule so much greater than that attained by the wings, that the latter are never allowed time
. Animal locomotion, or Walking, swimming, and flying, with a dissertation on aëronautics. Animal locomotion; Aeronautics. 160 AKIMAL LOCOMOTION. and as a consequence likewise of the speed at which the insect is travelling, the wings during the back stroke are for the most part actually travelling forwards. This is accounted for by the fact, that the body falls downwards and forwards in a curve during the up or return stroke of the wings, and be- cause the horizontal speed attained by the body is as a rule so much greater than that attained by the wings, that the latter are never allowed time to travel backward, the lesser movement being as it were swallowed up by the greater. For a similar reason, the passenger of a steam-ship may travel rapidly in the direction of the stern of the vessel, and yet be carried forward in space,—the ship sailing much quicker than he can walk. While the wing is descending, it is rotating upon its root as a centre (short axis). It is also, and this is a most important point, rotating upon its anterior margin (long axis), in such a manner as to cause the several parts of the wing to assume various angles of inclination with the horizon. Figs. 84 and 85 supply the necessary illustration. Fig. Fig. 85. In flexion, as a rule, the under surface of the wing (fig. 84 a) is arranged in the same plane Mnth the body, both being in a line with or making a slight angle with the horizon {x x)} ^ It happens occasionally in insects that the posterior margin of the wing is on a higher level than the anterior one towards the termination of the up stroke. In such cases the posterior margin is suddenly rotated in a downward. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Pettigrew, James Bell, 1834-1908. New York, D. Appleton & company
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectaeronau, bookyear1874
