VII FLIGHT 221 



Messrs. Wyles's photographs of Gulls, flying horizon- 

 tally at some height from the sea, there is not a single 

 one among the large number that has its wings flexed. 

 (See frontispiece.) 



Figures described by different parts of the Wing. 



If you take an insect (a Bluebottle, for instance, or a 

 Drone) and hold it down, the wing tips as they vibrate 



Fig. to (after Marey). 



Figure described by tip of Crow's wing. 1 



The backward movement neary? is largely due to the flexing, the forward movement 



near st to the straightening of the wing. 



will be seen to describe a figure of 8. If the sunlight 

 be made to fall upon them, it will be all the clearer. 

 I have tried painting the tips with body white, but 

 the rapid vibration soon dislodges the paint. It is 

 much harder to discover the trajectory of a bird's 

 wing. Professor Pettigrew has strongly insisted that 

 it is an 8 as in the case of insects, but the lower circle 



1 I have corrected the mistake by which the words " right " 

 and "left" have been accidentally transposed in Professor 

 Marey' s explanation of the figure. 



