[ar:MP3 同步字幕版(英音)]
[ti:Bird Flight]
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[00:01.53]Lesson 23
[00:03.66]Bird flight
[00:11.29]What are the two main types of bird flight described by the author?
[00:17.83]No two sorts of birds practise quite the same sort of flight;
[00:22.47]the varieties are infinite; but two classes may be roughly seen.
[00:28.50]Any ship that crosses the Pacific
[00:30.55]is accompanied for many days by the smaller albatross,
[00:34.82]which may keep company with the vessel for an hour
[00:37.76]without visible or more than occasional movement of wing.
[00:42.57]The currents of air that the walls of the ship direct upwards,
[00:46.67]as well as in the line of its course,
[00:49.21]are enough to give the great bird with its immense wings
[00:52.62]sufficient sustenance and progress.
[00:55.93]The albatross is the king of the gliders,
[00:59.41]the class of fliers which harness the air to their purpose,
[01:03.44]but must yield to its opposition.
[01:06.54]In the contrary school, the duck is supreme.
[01:10.93]It comes nearer to the engines with which man has 'conquered' the air, as he boasts.
[01:16.66]Duck, and like them the pigeons, are endowed with steel-like muscles,
[01:22.40]that are a good part of the weight of the bird,
[01:25.53]and these will ply the short wings with such irresistible power