Do. in or through the air, [103]
Quadrupeds walk, fishes swim, and insects, bats, and birds fly, by figure-of-8 movements, [15], [16]
Screws—the wing of the bird and the extremity of the biped and quadruped screws, structurally and functionally, [12]
Screws—difference between those formed by the wings and those employed in navigation, [151]
Sculling action of the wing, [231]
Speed attained by insects, [188]
Speed of wing movements partly accounted for, [120]
Spine, spiral movements of, transferred to the extremities, [33]
Straus-Durckheim’s artificial wings, [233]
Swimming of the fish, whale, porpoise, etc., [66]