80 RAPIDITY OF FLIGHT. 



(at first sight) most improbable capacity, so as to render it 

 no longer a matter of doubt or difficulty, but merely an ad- 

 ditional 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 skeleton. Sup- 

 pose, 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 them- 

 selves nearly sufficient to sustain its weight and float its 

 light body in the air. But in addition 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 happen ? That the heat of its circulation 

 (and it is well known that the heat of a bird's circulation is 

 considerably 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 surprising addi- 

 tional buoyancy or power of floating, even in the higher 

 regions of the atmosphere. And that this is the case may 

 be presumed from its habits; for when the lower currents of 

 air are stormy and disagreeable, up goes the Frigate-Bird 

 to a higher and calmer current, where, just as we see the 

 light fleecy clouds in the sky, it remains,^ suspended with 

 outspread wing, motionless, and at rest, till, roused by hunger, 

 it expels the rarefied air, and emptying its pouch, descends 

 towards the waves ; but as it never either dives or swims, on 

 approaching within a few feet, it instantly stops, and changes 

 its direction, so as to skim along and catch the flying-fish 

 with its hawk-like bill or talons, or both together. So averse 

 are they, in fact, to diving, or even touching the water, that, 

 instead of dashing downwards head foremost, like the Gannet 

 and other diving birds, the Frigate-Bird holds its neck and 

 feet in a horizontal direction; striking the upper column of 

 air with its wings, then raising and closing them one against 

 the other above its back, it darts on the flying-fish with such 

 skill and certainty, as almost invariably to insure success. 



