Wings 327 



state of our knowledge. Suffice it to say that if we will 

 think of a bird flying through the air when we ourselves 

 are swimming in the water, we can realize the achievement 

 more vividly than from any amount of descriptions and 

 diagrams. 



The under surface of a bird's wing is concave; and 



FIG. 262. Wing of living Golden Pheasant; rounded and curved for short, 



sudden flight. 



while the front edge is rather straight and firm, the hinder 

 rim of the feathers is soft and yielding; thus a downward 

 stroke both raises the bird or holds it sustained at the 

 height already reached and urges it in a forward direction. 

 Similarly we push our hollowed palms backward and pro- 

 pel ourselves through the denser medium of water. 

 The manner of flight varies greatly in different birds 



