106 ANIMALS AT WORK AND PL A Y 



each wing ; and these separate feathers, if there had 

 been the slightest vibratory motion ' [as by the theory 

 which we have mentioned], 'must have appeared 

 blended together. But they were seen distinct against 

 the clear blue sky. 1 



Soaring in such perfection is not an accomplish- 

 ment possessed by many of our English birds ; or, 

 rather, it is seldom exercised. But the writer has 

 seen a trained peregrine falcon soar at a vast height 

 exactly like the condors, and so much did the bird 

 enjoy the newly-discovered power for it was a young 

 one that had only been allowed to fly occasionally 

 that it was long before she would return to the lure. 

 Rooks will also soar, and kestrels late in March and 

 early in April. But this feat of the kestrels must not 

 be confused with their hovering, which is accomplished 

 by very rapid and partial beats of the wings. Gulls 

 also ' sail ' grandly, though not, as a rule, in such wide 

 circles as the birds we have mentioned. But in face 

 of facts, doubts were constantly thrown on the power 

 of birds to find in the force of the wind a power to 

 move against the wind itself. It was, some said, as 

 absurd as to expect that a log thrown into a river 

 could find in its currents a force able to make it 

 float against the stream. D'Esterno made careful 

 observations, and saw that they did sail without beat- 

 ing the wings, but admitted that he could not 



