WIND AND FLIGHT 151 



losing altitude as he goes. Not ^infrequently birds 

 change from a left-handed to a right-handed spiral ; 

 Gulls are very fond of this ; they often describe 

 very small " circles," revolving round the down- 

 ward-pointing inner-wing, and it may be that the 

 change to the right-handed spiral saves them from 

 giddiness. 



Mr. Peal was of opinion that the Adjutants, whose 

 soaring he studied so zealously, always made leeway 

 as they rose. But there seems to be no reason why 

 this should be so. It may have been that what 

 looked like a movement to leeward had for its object 

 the keeping within an upward slanting stream of air 

 on which they depended. There seems no reason 

 for an involuntary loss of leeway. Let us consider 

 a particular turn of the spiral from start to finish. 

 When the bird is facing the wind, he has only to 

 incline his body correctly and he will make headway. 

 When the wind strikes him from behind, he must 

 slope his body downward, otherwise there will be a 

 disarrangement of plumage, and there will result a 

 slight loss by leeway, though no loss of elevation 

 unless the bird so chooses. When he turns his side 

 to the wind he is free to set himself at any incline he 

 likes, and, according as he chooses, he will advance 

 or retreat. During far the greater part of the circle, 

 therefore, he is far from being the plaything of the 

 wind. As a matter of fact birds may be seen circling 

 over hill-tops without any loss by leeway, and I 

 believe I have seen them equally successful over 

 plains. There is this, too, to be remembered. When 

 a bird has gained all the altitude he wants, by gliding 

 slightly downward he can make headway in whatever 



