Yet it must be confessed that any attempt to explain 

 exactly how birds fly must fail. We can do no more than 

 state the more obvious factors which are indispensable to 

 flight, and the nature of its mechanism. The subtleties and 

 delicate adjustments of actual flight evade us. 



Our appreciation, however, of this supreme mode of 

 locomotion will be materially quickened, if we make a point 

 of studjang the varied forms of flight as opportunities present 

 themselves. 



To begin with, it is worth noting that the size of the 

 wing decreases with the weight of the body to be hfted — up 

 to a certain point, of course. This,, perhaps, may seem 

 a strange statement to make. But it can be readily verified. 

 Compare, for example, the size of the body in relation to the 

 wings, in the case of the butterfly and the dragon-fly, on 

 the one hand, and the partridge and the crow, on the 

 other. The two first named, by comparison, have enormous 

 wings. 



Birds, it will be noticed, which haunt woods, or thickets, 

 have short, rounded wings, like the wren, the pheasant, or 

 the tawny owl. Such, on the other hand, as live in the open, 

 Uke the gull, and the swallow, have long, pointed wings. The 

 reason for this is fairly plain. Birds which must steer their 

 course through the intricate mazes of a wood, or thicket, 

 would find their flight seriously hampered by long wings. 



22 



