232 BRITISH BIRDS. 



which extends the forearm. Another plan is to examine a number of 

 photographs. I have never seen one in which a bird's wing is 

 straightened at the elbow and at the same time bent (beyond a very 

 little) at the wrist. Certainly there is no example of this in any of the 

 excellent photographs with which Mr. Beetham's paper is illustrated. 

 There is no need to point out the importance to the bird of having 

 all the big and heavy muscles massed upon the body or near it. 



F. W. Headley. 



To the Editors of British Birds. 

 UNEQUAL WING-STROKES IN FLIGHT. 



Sirs, — Mr. Headley's explanations of his additional photographs 

 on page 192 are not more convincing to me than those referring to the 

 previous photographs. In both, the wings are held symmetrically. 

 In Fig. 1, p. 192, if lines be ruled through the tips of the primaries, 

 the edges of the longest secondaries, and tlirough the wrists of the 

 wings, these three lines will be found to converge to a point considerably 

 above the bird, this being so because the camera has been held pointing 

 down at it. The existence of this vanishing point shows that the 

 three sets of points occur on parallel lines, and it follows that the wings 

 are in a strictly symmetrical position. 



Fig. 2 is even clearer. The Pigeon is alighting with its wings thrown 

 back. The camera is viewing it a little from the right, and therefore 

 it shows an almost full view of the left wing, and a fore -shortened or 

 compressed view of the right. A book held open at an angle and a 

 little to the right of the eye will demonstrate the correctness of the 

 above opinion. A. W. Seaby. 



