vit FLIGHT 241 
Gull flying at right angles to it without moving his 
wings. A diagram will make clear the method. 
He descends swiftly at a gentle incline, making an 
angle with the wind that, but for leeway, would be a right 
angle, then suddenly turns and faces the wind, rising 
by a short steep ascent to his former level, after which 
he begins the process over again. He descends from 
the more rapid current into the slower, and so has the 
advantage of his relative velocity, after which he again 
ascends, and profits by his passage from the slower to 
the swifter. The upper current lends him pace, the 
Ww 
etnias tracttatren 
Fic. 64. 
W shows the direction of the wind ; G the line of the Gull’s flight. 
lower we may look upon asa floor off which he rebounds 
like a ball. As he ascends into the more quickly moving 
air, he has, belonging as he does now to the slower 
current below, an inertia which makes the wind act 
upon him as upon a kite. A glance at the line of his 
course will show how he keeps making good his leeway 
as he goes. The Albatross, those who have been lucky 
enough to see him say, has brought this mode of pro- 
gression to perfection, working onward by the hour 
without a motionof his wings. A Gullis often reduced 
to putting in a stroke or two, though I have seen them 
cover a considerable distance without once resorting to 
this. It is said that some birds make head directly 
R 
