File:Animal locomotion, or Walking, swimming, and flying, with a dissertation on aëronautics (1874) (17577200933).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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PROGRESSION ON THE LAND. 59 of the feet and limbs upon the trunk, generate a forward wav^e movement, accompanied by a certain amount of vertical undulation. The diagonal movements of the trunk and extremities are accompanied by a certain degree of lateral curvature; the right leg and left arm, when they advance to make a step, each describing a curve, the convexity of which is directed to the right and left respectively. Similar curves are described by the left leg and right arm in making the second or complementary step- When the curves formed by the right and left legs or the right and left arms are joined, they form waved tracks symmetrically arranged on either side of a given line. The curves formed by the legs and 4 5 67 8 910 11 12 13 11 12 3
Text Appearing After Image:
¥ia. 27 shows the simultaneous positions of both legs during a step, divided into four groups. The first group (A), 4 to 7, gives the different positions which the legs simultaneously assume while both are on the ground; the second group (5), 8 to 11, shows the various positions of both legs at the time when the posterior leg is elevated from the ground, but behind the supported one; the third group (C), 12 to 14, shows the positions which the legs assume when the swinging leg overtakes the standing one; and the fourth group (D), 1 to 3, the positions during the time when the swing- ing leg is propelled in advance of the resting one. The letters «, b, and c indicate the angles formed by the bones of the right leg when engaged in making a step. The letters w, n, and o, the positions assumed by the right foot when the trunk is rolling over it. g Shows the rotating forward of the trunk ui)on the left foot (/) as an axis, h Shows the rotating forward of the left leg and foot upon the trunk (a) as an axis. Compare with fig. 4, p. 21; with fig. 24, p. 47; and with fig. 26, p. 55.—After Weber. aims intersect at every step, as shown at fig. 19, p. 39. Similar curves are formed by the quadruped when walking

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