THE BIRD IN THE AIR. 



As long ago as King Solomon, who was the first naturalist, 

 "the way of the bird in the air " was one of the stock mysteries 

 for men to wonder over. How does a bird fly ? It is only 

 recently that the secret has been discovered. 



In order to fly a bird must have wings large enough to 

 support his weight, and muscles strong enough to move his 

 wings; there seems to be nothing else required beyond a 

 proper adjustment of power and supporting surface. We do 

 not at first observe any such wonderful adaptations in wings 

 as we saw in the loon's foot to fit it for a life in the water — 

 merely more or less wing, longer or shorter, pointed or rounded. 

 But the wonderful thing is that the bird can fly at all. 



Here we have the problem in its simplest form : how is an 

 eagle, weighing ten pounds, to raise himself in the air by 

 flapping two broad fans that spread from tip to tip some seven 

 feet ? Some say that his hollow bones and the air-sacs in his 

 body help to lift him, — as if a bird were a balloon. But a 

 balloon, if filled with air, would rise no more than a grocery 

 bag blown full and tied ; a balloon is always filled with a gas 

 lighter than air. An eagle can never, by any kind of puffing 

 himself up with air, diminish that ten pounds in weight, 

 even by a single ounce. The balloon theory finds two other 

 obstacles — a balloon must sail before the wind, and it can 

 travel no faster than the breeze that bears it, while the bird's 

 speed is voluntary, and he usually prefers to fly against the 

 wind. The bird's power to fill himself with air does not 

 account for his flying. 



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