Annual Report of the Aeronautical Society of Great BritainAeronautical Society of Great Britain, 1877 |
Άλλες εκδόσεις - Προβολή όλων
Συχνά εμφανιζόμενοι όροι και φράσεις
action aërial navigation Aëronautical Society aërostat albatross angle apparatus art of flying ascend balloon bird bird flight bird's Blackheath body Brearey captive balloons carried centre of gravity CHAIRMAN condor constructed cord Council descent diameter direction Duke Duke of Argyll effect elevation engine exerted experiments fact feathers feet flight floating flying machine force forward give horizontal hydrogen inches inclined inclined plane increase india-rubber JAMES GLAISHER kite lifting LINFIELD Little Clarendon Street LORD RICHARD GROSVENOR means ment miles an hour Mosment motion motive power moving nature necessary observations obtained pair of wings paper parachute plane pounds pressure principle propelling propulsion remarks resistance result Royal Horse Guards sailing screw ship SIMMONS soaring specific gravity speed square steam Street stroke sufficient suppose sustain tail theory upward velocity vertical vessel weight WENHAM West Wratting wind wing surface
Δημοφιλή αποσπάσματα
Σελίδα 30 - There be three things which are too wonderful for me, yea, four which I know not: The way of an eagle in the air; the way of a serpent upon a rock; the way of a ship in the midst of the sea; and the way of a man with a maid.
Σελίδα 12 - Having remarked how thin a stratum of air is displaced beneath the wings of a bird in rapid flight, it follows that in order to obtain the necessary length of plane for supporting heavy weights, the surfaces may be superposed, or placed in parallel rows, with an interval between them.
Σελίδα 39 - ... the sustaining power is greatly influenced by the form and arrangement of the surface. ' In the case of perpendicular descent, as a parachute, the sustaining effect will be much the same, whatever the figure of the outline of the superficies may be, and a circle perhaps affords the best resistance of any. Take, for example, a circle of twenty square feet (as possessed by the pelican) loaded with as many pounds.
Σελίδα 12 - ... displaced beneath the wings of a bird in rapid flight, it follows that in order to obtain the necessary length of plane for supporting heavy weights, the surfaces may be superposed, or placed in parallel rows, with an interval between them. A dozen pelicans may fly one above the other without mutual impediment, as if framed together ; and it is thus shown how two hundredweight may be supported in a transverse distance of only ten feet.
Σελίδα 15 - On nearing our own shores, steaming against a moderate head-wind, from a station abaft the wheel the movements of some half-dozen gulls are observed, following in the wake of the ship, in patient expectation of any edibles that may be thrown overboard. One that is more familiar than the rest comes so near at times that the winnowing of his wings can be heard ; he has just dropped astern, and now comes on again. With the axis of his body exactly at the level of the eyesight, his every movement can...
Σελίδα 16 - With the axis of his body exactly at the level of the eyesight, his every movement can be distinctly marked. He approaches to within ten yards, and utters his wild plaintive note, as he turns his head from side to side, and regards us with his jet black eye. But where is the angle or upward rise of his wings, that should compensate for his descending tendency, in a yielding medium like air? The incline cannot be detected, for, to all appearance, his wings are edgewise, or parallel to his line of...
Σελίδα 78 - ... are of necessity uncertain, whereas if actual velocities can be certainly and accurately known, it will become very easy to make reliable experiments upon pressures, the effect of differently-shaped surfaces, &c. The apparatus which I would propose consists essentially of bodies travelling in the direction of, and at the same velocity as the wind, and of mechanism for indicating and recording the rapidity of their motion. It is evident that in this way, if perfectly carried out, a direct measurement...
Σελίδα 17 - ... An approach to within 80 yards arouses the king of birds from his apathy. He partly opens his enormous wings, but stirs not yet from his station. On gaining a few feet more he begins to walk away with half expanded but motionless wings.
Σελίδα 38 - The great feathers, that were of a beautiful shining black, were two feet four inches long. The thickness of the beak was proportionable to the rest of the body ; the length about four inches ; the point hooked downwards, and white at its extremity ; and the other part was of a jet black.
Σελίδα 39 - ... the bird, forced down in order to give a more secure hold upon the air below, and by that means keep the bird up. Now if we do but examine the quill feathers we shall find in the shafts astonishing strength with elasticity, and very little specific gravity indeed. The webs of the quill feathers are broader on one side of the shaft than the other, which causes them to open as the wings move up and to shut as they come down, exactly answering the purposes I have already mentioned ; therefore, we...