356 BRITISH BIRDS. 



webs extended in anticipation of the coming contact. 

 That a great strain is being placed upon the wings, and 

 that therefore a great resistance is being encountered, 

 is indicated by the curve of the primaries. 



Figure 4 shows the position a moment later. The 

 bird has now got its feet upon the rock (or rather one 

 foot, for the other is thrust out horizontally on the nest, 

 having no doubt missed its mark, and can be of little, if 

 any, support), and appears to be almost stationary, but 

 as a matter of fact it has still a forward impetus which the 

 raised wings are trying to counteract. The bird has, 

 indeed, just set foot upon the ledge, and is falling forward 

 in the direction of its approach. 



The last photograph (Figure 5) again carries us on a 

 brief moment. Now the bird has pitched forward on 

 to its breast, its wings having failed to find sufficient 

 resistance in the air to counteract the body's momentum, 

 and in consequence the wings have come crashing down 

 upon the rocks at the end of their strenuous beat. The 

 position of the tail is interesting ; in Figure 3 it is seen 

 fully expanded and depressed in order that its ventral 

 surface may oppose the forward progress, and now it is 

 turned upwards above the back so that its dorsal surface 

 may find resistance and try to counteract the tendency 

 to pitch forward on to the breast. 



