 In the case of any bird soaring, its motion must be sufficiently rapid, so that the action of the inclined surface of its body on the atmosphere may counterbalance its gravity. The force to keep up the momentum of a body moving in a horizontal plane in...  The Harvard Classics - Стр. 1991909Полный просмотр - Подробнее о книге
 | Railway readings - 1847 - Страниц: 172
...The propelling force in their motion is greatly derived from the head and neck. It is truly wonderful to see so great a bird, hour after hour, without any...exertion, wheeling and gliding over mountain and river. (Darwin^ South America.) Poison of Vipers.—Mr. Humboldt has observed, that in the recent experiments... | |
 | Philip Henry Gosse - 1849 - Страниц: 344
...its gravity. The force to keep up the momentum of a body moving in a horizontal plane in that fluid (in which there is so little friction) cannot be great;...exertion, wheeling and gliding over mountain and river." Mr. Darwin supposes that the Condor breeds only once in two years, that it lays two large white eggs... | |
 | William Dowling - 1849 - Страниц: 356
...if the extended wings formed the fulcrum on which the movements of the neck, body, and tail acted. It is truly wonderful and beautiful to see so great...exertion, wheeling and gliding over mountain and river." It is only recently that the true history of the condor has become known, many wild tales having been... | |
 | John George Wood - 1862 - Страниц: 804
...its gravity. The force to keep up the momentum of a body moving in a horizontal plane in that fluid (in which there is so little friction) cannot be great,...of the neck and body of the Condor we must suppose sufficient for this. However this may be, it is truly wonderful and beautiful to see so great a bird,... | |
 | John George Wood - 1862 - Страниц: 804
...its gravity. The force to keep up the momentum of a body moving in a horizontal plane in that fluid (in which there is so little friction) cannot be great,...of the neck and body of the Condor we must suppose sufficient for this. However this may be, it is truly wonderful and beautiful to see so great a bird,... | |
 | John George Wood - 1862 - Страниц: 804
...its gravity. The force to keep up the momentum of a body moving in a horizontal plane in that fluid (in which there is so little friction) cannot be great,...of the neck and body of the Condor we must suppose sufficient for this. However this may be, it is truly wonderful and beautiful to see so great a bird,... | |
 | John George Wood - 1831 - Страниц: 802
...its gravity. The force to keep up the momentum of a body moving in a horizontal plane in that fluid (in which there is so little friction) cannot be great,...of the neck and body of the Condor we must suppose sufficient for this. However this may be, it is truly wonderful and beautiful to see so great a bird,... | |
 | Aeronautical Society of Great Britain - 1883 - Страниц: 488
...counterbalance its gravity. The force to keep up the momentum of a body moving in a horizontal plane in the air (in which there is so little friction) cannot...exertion, wheeling and gliding over mountain and river." So far as the soaring birds are concerned the case might rest here. Observe that the strongest and... | |
 | Albert Taylor Bledsoe, Sophia M'Ilvaine Bledsoe Herrick - 1870 - Страниц: 510
...counter-balance its gravity. The force to keep up the momentum of a body moving in a horizontal plane in the air (in which there is so little friction) cannot...exertion, wheeling and gliding over mountain and river.' He says also that 'the head and neck were moved frequently, and apparently with force.' Recognizing,... | |
 | Henry Mills Alden, Frederick Lewis Allen, Lee Foster Hartman, Thomas Bucklin Wells - 1871 - Страниц: 980
...momentum of a body moving in a horizontal plane in the air (in which there is so little friction) can not be great, and this force is all that is wanted. The...the condor we must suppose is sufficient for this." In this account, as in all others I have seen, the one important element is overlooked — the force... | |
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