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Bird flight
鸟的飞行方法
No two sorts of birds practise quite the same sort of flight; the varieties are infinite; but two classes may be roughly seen. Any shi that crosses the Pacific is accompanied for many days by the smaller albatross, Which may keep company with the vessel for an hour without visible or more than occasional movement of wing. The currents of air that the walls of the ship direct upwards, as well as in the line of its course, are enough to give the great bird with its immense wings sufficient sustenance and progress. The albatross is the king of the gliders, the class of fliers which harness the air to their purpose, but must yield to its opposition. In the contrary school, the duck is supreme. It comes nearer to the engines with which man has 'conquered' the air, as he boasts.