The California Gull 



Taken in Seattle 



Photo by the Author 



of the game, he shot forward. And again, there was not in the motion the 

 slightest perceptible effort of propulsion, but only a slightly sharper incli- 

 nation of the body and wings downward. 



This challenging mystery of effortless flight has found a rational 

 explanation at last. Theoretically, at least, automotive engineers have 

 come to realize that the propulsive thrust whereby the bird is driven 

 against and through the very wind which impels it, is due to the perfection 

 of the stream-lining of the bird's body and wings. Just as a fresh water- 

 melon seed escapes from the pressed thumb and finger, so a bird's wing, 

 squeezed above and below by the resolving elements of the wind, shoots 

 forward. These are deep waters for a layman, but I have discoursed with 

 a reputable engineer who claims to have produced models wherein the 

 frontal resistance is reduced to four per cent (of the normally opposed 

 flat surface), and who dreams of an airplane so cunningly contrived that 

 the frontal resistance will be transferred to the minus side of the account. 

 Such a machine could fly faster against an opposing Avind than with it, 

 and given a sufficient elevation to guard against air holes or momentary 

 imperfections in balancing, could advance against the wind (and only so) 



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