PREPARING FOR THE JOURNEY 



machines which would have wings like those of 

 birds. But he never succeeded. He could not 

 make even a feather! Finally he discovered that 

 if he would make a machine that would fly, he 

 must give it wings and an engine. So he con- 

 structed an aeroplane which has wide, stiff wings 

 or planes measuring about thirty feet from tip 

 to tip. These wings cannot be flapped, and, in 

 themselves, they furnish no power. But to them 

 man added an engine driven by gasoline and 

 electricity. This engine turns a long-bladed pro- 

 peller which urges the aeroplane forward, while 

 the planes support it when it is in motion. But 

 a bird's wing, we must remember, is both plane 

 and engine. It gives support as well as power. 

 It is therefore a far more remarkable machine 

 than the one made by man. 



Now let us see some kinds of birds' engines. 

 Although they all work on the same principle 

 they differ greatly in shape and size. We shall 

 find that most birds which make long journeys 

 have one kind of engine, while those that travel 

 but little have quite a different looking engine. 

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