The Sparrow >-hawJc. 



69 



escape at the rounded end, that is, at right angles 

 to the bird. But it is the air which escapes at the 



FIG. 13. 



Foot of Sparrow-hawk, showing slender toes, and strong, curved claws. 

 .From, nature. Natural size. 



back of the wing that is the means of the bird's 

 propulsion, and, therefore, the air which passes at 

 the end of the wing is useless for this purpose. 



On the other hand, when we examine the wing of 

 a sharp- winged hawk, such as a Merlin (Fig. 15), 

 we see at once that the air cannot escape at the end, 

 since it comes to a point, and therefore it must all 

 be forced to the back of the wing, the yielding 

 nature of which allows the air to lift up the ends 

 of the feathers, and thus push the bird forward. 



The round wing of the Sparrow-hawk, therefore, 

 prevents it from overtaking a quick-flying bird in a 

 long chase, and hence its stealthy habits when 



