The Bird Book 



a balloon whither every current carried it. The 

 wings would be useless, for there would be no 

 fulcrum from which they could act. Weight 

 supplies this fulcrum and at the same time gives 

 momentum, thus enabling a high speed to be 

 maintained for a considerable time. But the 

 weight must be proportionate to the area of the 

 wings, and this calls for a nice adjustment. Take 

 the case of the Razorbill, a diving sea-bird. The 

 adjustment is here pushed almost to its extreme 

 limit, for the wings have to serve a double pur- 

 pose ; they are used as fins or flippers in swimming 

 under water as well as for flight. The area has 

 therefore to be reduced to a minimum to be used 

 with effect in the water, and yet it must be just 

 large enough to enable the bird to fly. The body 

 is proportionately very heavy and the bird has the 

 greatest difficulty in rising from the sea when it is 

 calm and there is little or no wind to rise against. 

 The bird cannot indeed turn and wheel with the 

 ease and grace of a Swallow, but where is the 

 need ? The ocean is its home, and there, at least, 

 is almost limitless space for the Razorbills to go 

 on their way rejoicing. 



In a practical handbook on British Birds any 

 remarks on the Great Auk may well seem out of 

 place, but its history well illustrates the nemesis 

 that overtakes any flagrant violation of the prin- 

 ciples of flight. The Great Auk is (or, rather, 

 was) in every particular except the wing a Razor- 

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