624 



BIRDS. 



it, surpasses it, outraces it ; is the air, conscious of itself, conquering 

 itself, ruling itself. " 



Ruskin has compared the flight of a bird to the sailing of a boat. " In 

 a boat, the air strikes the sail ; in a bird, the sail strikes the air ; in a 



FIG. 222. Wings coming down. (From MAREY.) 



boat, the force is lateral, and in a bird downwards ; and it has its sail 

 on both sides. " But, as he says, the sail of a boat serves only to carry 

 it onwards, while wings have not only to waft the bird onwards, but to 



FIG. 223. Wings completely depressed. (From MAREY.) 



keep it up. To carry the weight of the bird the wings strike vertically, 



sometimes the direction 

 bird mounts upwards ; 



K-CCp 11 U]J. JL U L,fcUI_y LUC WClgUL Ul LUC UUU LUC W _ 



to carry the bird onwards they strike obliquely ; sometimes the direction 

 of the stroke is more vertical, and then the bir 



