92 THE RED-TAILED HAWK. 



How much there is in the flight of a bird! Full well has 

 the Duke of Argyll seized upon it as an unmistakable evi- 

 dence of design in nature. From the fish darting through 

 the pathless waters, or the serpent gliding without legs or 

 feet along the ground, or the frog leaping with surprising 

 elasticity, or the stately stepping of the steed, up through 

 all the various styles and methods of animal locomotion, to 

 the eagle which soars above the clouds, the flight of birds 

 is by far the most interesting and wonderful. How that 

 Hawk floats like something ethereal in the atmosphere! His 

 lungs affording communication with a system of large cavi- 

 ties throughout the body, the bones and muscles, even, and 

 the spaces between the body and the skin being pervaded 

 by the ramifications of air-cells, every respiration literally 

 fills him; and this inhaled air being rarefied by the heat of 

 his body, not to speak of the innumerable interspaces of 

 the light plumage, all pervaded by the external air, he is 

 almost as light as the clouds themselves. If the reader has 

 ever climbed a mountain, and known the intoxication of 

 delightful sensations produced by a rarefied atmosphere, he 

 may form some conception of what must be the pleasurable 

 sensations of this soaring creature. 



As to the act of flight itself, the upper side of the wing 

 being convex, and the wing somewhat drawn together, the 

 upward stroke in flight meets but little resistance, while the 

 under side, which is concave, incloses the atmosphere in the 

 downward stroke of the fully-extended wing, and so secures 

 the full force of its elasticity. This, however, simply 

 enables the bird to rise. What carries it forward ? The air, 

 escaping behind the long, elastic pinions, drives it on, some- 

 what as the wind, escaping behind the sail, propels the boat. 

 The sailing of the bird, with steady, motionless wings, is 

 accomplished by a nice adjustment of the wing to the 



