228 THE STRUCTURE AND LIFE OF BIRDS chap. 



I think, least of all. The pelican's flight I do not 

 know, but the rest ascend by a comparatively gentle 

 gradient ; some of them even require the help of a 

 head wind, if the ascent is to be made with reasonable 

 ease. The cormorant, when he leaves his fishing, 

 struggles hard before he gets clear of the water, 

 advancing quickly but ascending slowly, a striking 

 contrast in every way to the skylark as he mounts 

 lightly to the upper air. 



Downward Flight. 



It is a beautiful thing to see a pigeon, with wings 

 partly flexed, glide downwards through the air, then, 

 as he nears the ground, suddenly give his body an 

 upward instead of a downward slope, spread his wings 

 to stop himself, and, with all the grace of the " Herald 

 Mercury," alight. 



The suddenness of the change from horizontal or 

 upward to downward flight is very striking. It is often 

 maintained that it is due to a shifting of the centre of 

 gravity by the elongation of the neck or of the legs, or 

 by some of the other little manoeuvres known to birds, 

 which have this object. But the pigeon has no length 

 of neck or legs to extend. If you watch him change 

 all at once the incline of his body, you will see no 

 working of either. The very quickness of the move- 

 ment shows that it must be due to muscular action, 

 and it is no doubt the work of the muscle called the 

 Latissimus Dorsi, which in horizontal flight raises the 

 hinder quarters by hauling upon the wings and which, 

 as I have shown, probably helps in the process of 

 breathing (see p. 89). 



