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 \'ividl}' 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 



