RAPIDITY OF FLIGHT. 83 



upon the waves; as its feet are but partially webbed, and 

 in addition to its length of wing, which renders it as 

 difficult to rise from a flat-water surface as from the 

 level ground of the land, its feathers are not of that 

 close and downy texture peculiar to aquatic birds. 

 Whereas, its whole form and internal arrangements are 

 calculated for, it may be almost said, eternal flight. Its 

 length of wing, ten or twelve feet from tip to tip, forked 

 tail, and short legs, (the thighs or tarsi not exceeding an 

 inch in length,) bear a close resemblance to those of our 

 common Swift, of whose wonderful powers of flight we 

 have said so much; but nature has provided the Frigate- 

 Bird with still more surprising means, for not only 

 floating for a time, but for ever, without fatigue in the 

 regions of air, and even sleep without risk of falling; we 

 shall endeavour to explain this (at first sight) most im- 

 probable capacity, so as to render it no longer a matter 

 of doubt or difficulty, but merely an additional instance 

 of the beautiful arrangement adopted by the providence 

 of God in all his wondrous works. 



On examining it, we shall find just beneath the throat 

 a large pouch communicating with the lungs, and with 

 the hollow and particularly light bone-work of its skele- 

 ton. Suppose, then, that the bird wishes to rest in the 

 air; in the first place, it avails itself of its large wings, 

 which it is enabled by constant habit to keep expanded, 

 and which are in themselves nearly sufficient to sustain its 

 weight and float its light body in the air. But, in addi- 

 tion to the wing, suppose the bird fills its large pouch 

 with air, and from thence forces it into all its bones and 

 cavities between the flesh and the skin, what will hap- 

 pen? That the heat of its circulation (and it is well 

 known that the heat of a bird's circulation is consider- 

 ably beyond that of other animals) will rarefy the 

 internal air; which will therefore puff up, not only the 

 pouch, but every cavity, and thus give the bird a sur- 

 prising additional buoyancy or power of floating, even 

 in the higher regions of the atmosphere. And that this 



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