. Animal mechanism: a treatise on terrestrial and aerial locomotion. Animal locomotion. 200 ANIMAL MKCIIAMSM. which impels tin- insect forwards. This resultant acts in the descent of the wing1, as well as iu its upward movement, so that each part of the oscill itiou of tin- wing lias ;n action favourable to the propulsion of the animal. An effect is produced analogous with that which takes place when an oar is used in the stern of a boat in the action of sculling. Each stroke of the oar, which presents an inclined plane to the resisting water, divides this resistance into two forces: one acts
. Animal mechanism: a treatise on terrestrial and aerial locomotion. Animal locomotion. 200 ANIMAL MKCIIAMSM. which impels tin- insect forwards. This resultant acts in the descent of the wing1, as well as iu its upward movement, so that each part of the oscill itiou of tin- wing lias ;n action favourable to the propulsion of the animal. An effect is produced analogous with that which takes place when an oar is used in the stern of a boat in the action of sculling. Each stroke of the oar, which presents an inclined plane to the resisting water, divides this resistance into two forces: one acts in a direction oppose,1 to the motion of the oar, the other, in a direction perpendicular to that movement, and it is the latter which impels the boat. Most of the propellers which act in water overcome the resistance of the fluid l>y the action of an inclined plane. The tail of the fish produces a propulsion of this kind; that of the beaver does the same, with this difference, that it oscillates in a vertical plane. Even the screw may be con- sidered as an inclined plane, movement is continuous, and alwnvs in the same FJO. 85 R '1'i' cf thu chiiugus in the i> of the insert's wing. If we wish to represent the inclination of the plane of the wing at the different parts of fts course, we shall obtain fig. ;, in which the arrows indicate the direction of the course, of (he wing, and the lines, whether dotted or full, show the inclination of its plane. After this, we need only show the figure traced by Dr. Pet- ti^-rew in his work on flight, to prove how far the ideas of tliis English writer differ from ours The trajectory of the wing is represented by l)r. 1'etti- grew by means of fig. SU. Four arrows indicate, according to this writer, the direction of movements in the different por-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectanimall, bookyear1879
