BOOK OF NATURE LAID OPEN. ' 65 



one leg, and then making a bound forward with the 

 other, proceeds with such amazing speed, that the 

 swiftest racer would be unable to maintain the pur- 

 suit ! 



In the structure of Birds of the more perfect order, 

 a few things demand our most serious attention : 



The whole body is 'shaped in the most convenient 

 manner for making their way through the air ; be- 

 ing, as Mr. Ray observes, constructed very near Sir 

 Isaac Newton's form of least resistance. According 

 to Bar, in his continuation of Buffon, " It is neither 

 extremely massive nor equally substantial in all its 

 parts ; but, being designed to rise in the air, is capa- 

 ble of expanding a large surface without solidity. 

 The body is sharp before, to pierce and make its 

 way through that element; it then gradually in- 

 creases in, bulk, till it has acquired its just dimen- 

 sions, and falls off in an expansive tail." 



The motion of this order being two-fold, walking 

 and flying, they are provided with legs at once 

 wonderfully contrived to walk with, and raise them 

 like a spring for their flight ; wings to buoy them 

 up and waft them along ; and a tail to keep them 

 steady in the air, assist them in their evolutions, 

 and to direct their course. 



Although their feathery covering is admirably 

 constructed for lightness and buoyancy, their wings 

 are furnished with a strength that is amazing ; so 

 that the flap of a Swan's wing has been known to 

 break a man's leg: and a similar blow from an Ea- 

 gle has produced instant death ; and by these they 

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