Weight necessary to flight, 3 The same laws regulate natural and artificial progression, 4 Walking, swimming, and flying correlated, 5 Flight the poetry of motion, 6 Flight a more unstable movement than that of walking and swimming; the travelling surfaces and movements of animals adapted to the earth, the water, and the air, 7 The earth, the water, and the air furnish the fulcra for the levers formed by the travelling surfaces of animals, 8 Weight plays an important part in walking, swimming, and flying, 9 The extremities of animals in walking act as pendulums, and describe figure-of-8 curves, 9 In swimming, the body of the fish is thrown into figure-of-8 curves, 10 The tail of the fish made to vibrate pendulum fashion, 11 The tail of the fish, the wing of the bird, and the extremity of the biped and quadruped are screws structurally and functionally. They describe figure-of-8 and waved tracks, 12 The body and wing reciprocate in flight; the body rising when the wing is falling, and _vice versâ_, 12 Flight the least fatiguing kind of motion. Aërial creatures not stronger than terrestrial ones, 13 Fins, flippers, and wings form mobile helics or screws, 14 Artificial fins, flippers, and wings adapted for navigating the water and air, 14 History of the figure-of-8 theory of walking, swimming, and flying, 15 Priority of discovery on the part of the Author. Admission to that effect on the part of Professor Marey, 16 Fundamental axioms. Of uniform motion. Motion uniformly varied, 17 The legs move by the force of gravity. Resistance of fluids. Mechanical effects of fluids on animals immersed in them. Centre of gravity, 18 The three orders of lever, 19 Passive organs of locomotion. Bones, 21 Joints, 23 Ligaments. Effects of atmospheric pressure on limbs. Active organs of locomotion. Muscles; their properties, arrangement, modes of action, etc., 24 Muscular cycles. Centripetal and centrifugal movements of muscles; muscular waves. Muscles arranged in longitudinal, transverse, and oblique spiral lines, 25–27 The bones of the extremities twisted and spiral, 28