FLIGHT

is the pa age of an animal through the air by means of wings, which are limbs specially adapted for the purpose. Flying animals—which include insects, birds, and bats, but not so-called flying squirrels, flying opo ums, or flying fish—whatever their species and however different the appearance of their wings, all fly according to the same principles. It has been supposed that the air-sacs and cavities in the bones of birds when filled with heated air support the birds after the manner of a balloon; but this has been disproved, the purpose of the sacs being to a ist in regulating the temperature and in aerating the lungs more completely, and the flight of birds is due to the weight of the animal and the power of the wings inducing a resistance in the air sufficient to propel it upwards and onwards. Weight is as nece ary as power for the purpose of flight, as, without sufficient weight to overcome air currents simply by inertia, the animal would be unable to direct its movements, and would be at the mercy of every wind that blows. This | fact is greatly in favor of the idea that a flying machine should not be a light balloon structure, having a very large surface exposed, but should be comparatively heavy and compact, depending for its ability to fly solely on the power of its flying mechanism. Petti grew (1867) has shown that the wings of all flying animals are built as screws, and when they vibrate they twist in opposite directions during the up and the down strokes, striking upwards and forwards for the up strokes, and downwards and forwards during the down strokes, pa ing through the air obliquely as a boy’s kite when pulled on, or as an oar in the water in rowing. Prof. Marey, a few years afterwards, elaborated the theories of Petti grew by means of the sphygmograph (an — instrument in which movements are recorded by a pointer on a revolving — drum) and by photography, showing — the movements of the erent feathers — win; slowly, while the resistance of the air/the is also greater to a swiftly moving object | than to one moving slowly, so that the propulsion of the animal is much a isted. This may also be brought about by-the velocity of the wind being high, so that one sees birds flying easily a breeze with but little movement of their wings. Since the parts of the wing nearest to the body of the animal ba than through a very much shorter SEAGE those farthest away in exactly the same time,. r 4 H the wing is nece ari ly to an elastic body so as to avoid violent vibration. A * of its parts. The most notable application of the theories of flight to actual flying was made by S. P. Langley, | 02 the American scientist, who devoted all his mature life to the study of aeronautics, He achieved the first actual flight in the air, and the application of his theories by the Wright brothers | led to their final succe . See Lanauny, |i2 Eng. explorer; entered navy, 1790;)Was fought in Bellerophon, 1794; surveyed | great part of Australian coast, 1795-96, | discovering Ba Strait; led expedition | to explore Australian coast, 1801; on return wrecked, and imprisoned at Mauritiu s for six years; returned to England, 1810; pub. A Voyage to Terra Australis, 1814. - ‘