VARIETIES OF WING AND OF FLIGHT 101 
if we bear in mind that he carries his long legs 
stretched out behind. But his breastbone is short 
and deep, so that the great weight of muscle lies 
forward. Occasionally he may be seen to extend 
his neck full length, apparently for balancing pur- 
poses. The Stork is long-legged and the Flamingo 
still more long-legged, and both of them carry their 
necks and legs straight out. This is the normal 
attitude also of birds of prey. The Stilt, too, flies 
with his marvellous legs streaming out behind him ; 
his style of flight is well shown in a drawing in Mr. 
Abel Chapman’s Wild Spain. 
Flight in Flocks. 
When birds fly in a flock, great or small, they often 
adopt a particular formation, very commonly that 
of a V, and this is sometimes spoken of as if it had 
some special merit. But really the only important 
thing for each bird is to keep clear of the wash of 
his predecessor and the broken columns of air that 
he leaves behind him. The force of the wash is the 
measure of the vigour a bird puts into his wing- 
strokes ; it will not do, therefore, to travel close in 
the wake of another bird. The bicyclist, on the 
other hand, breaks the resistance of the air, and the 
man who rides close behind another has an advantage 
since he finds the air more yielding. As the man in 
front is not riding on the air there is no back-current 
behind him (see p. 4). 
The Whir of Wings. 
Everyone must have noticed the different notes 
given out by the wings of different kinds of birds as 
