CHAPTER VIII. 

 VARIETIES OF WING AND OF FLIGHT. 



CURVE — NARROW AND BROAD WINGS STYLES OF FLIGHT 



FLIGHT IN FLOCKS THE WHIR OF WINGS. 



Curve. Narrow and Broad Wings. 



I shall first consider the question of curve, or, as 

 the aviators call it, of camber — a question of the 

 utmost importance. The wings of all birds are a 

 good deal curved from front to back, so that as they 

 descend they catch the air in a concavity and have 

 plenty of lifting power. In some birds the front-to- 

 back curve extends throughout the whole length of 

 the wing, though in all there is some shallowing 

 towards the tip. The Jay and the Red-legged 

 Partridge (and their allies) supply good examples of 

 a curve that shallows near the tip of the wing but 

 does not disappear. In a Jay, of whose wings I made 

 measurements, the depth of the curve — measured 

 just on the near side of the starting-point of the 

 bastard-wing — was 1 inch (see PI. xv and also xiii 

 and xiv ). The breadth of the wing at this point 

 was 5 1 inches. Thus the curve is 1 in 5|, a curve 

 such as no aviator would ever think of using. But 

 it must be remembered that during the down-stroke 

 it is much reduced by the pliancy of the feathers, 

 which yield to the pressure of the air. The span 



