Lesson 23
Bird flight
What are the two main types of bird flight described by the author?
No two sorts of birds practise quite the same sort of flight;
the varieties are infinite; but two classes may be roughly seen.
Any ship 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.
Duck, and like them the pigeons, are endowed with steel-like muscles,
that are a good part of the weight of the bird,