way against a head- wind with the minimum of effort, by 

 partly flexing the wings and ghding downwards : at the end 

 of the descent, by turning the body sharply upwards, and 

 spreading the wings to the fullest extent, they are lifted up, 

 and driven forward, hke a kite. 



Marey and Pettigrew, long ago, showed conclusively, by 

 means of photography, that our conception of the movement 

 of the wing during flight was far from correct. 



To avoid a long and tedious description, and many techni- 

 calities, it must suffice to say that the wing of a bird possesses 

 very considerable freedom and range of movement at the 

 shoulder-joint. Certainly, during some phases of flight, the 

 wings are thrust forward and extended to their fullest extent, 

 so that the outer margins of the wings come to lie almost 

 parallel with the long axis of the body, as may be seen in the 

 spirited illustration showing the goshawk in flight. As they 

 sweep downwards, and backwards, they lift the body and 

 drive it forwards. At the end of the " sweep " they are 

 " flexed," that is to say, bent at the elbow and wrist-joints, 

 while at the same time they are raised and brought forward 

 above the body for a repetition of the stroke. These move- 

 ments are too quick for the eye to follow, but they have been 

 fixed for us by the camera. 



Marey devised an ingenious experiment in his endeavour 

 to discover the movements of the bird's wing during flight. 



37 



