BIRD PROBLEMS 211 



II 



THE POWER AND SPEED OF FLIGHT IN BIRDS 



THERE is nothing more wonderful in Nature than the 

 power of flight possessed by birds, and no subject 

 which yields more startling facts upon investigation. 

 " The way of an eagle in the air " is one of those 

 things of which Solomon expressed himself ignorant ; 

 and there is something truly marvellous in the 

 mechanism which controls the scythe-like sweep of 

 wings peculiar to most birds of prey. The power of 

 flight being almost exclusively the characteristic 

 attribute of birds, it is somewhat strange that even 

 the most eminent naturalists should be silent upon 

 it. And yet this is almost universally so. Those 

 that mention it do so upon the most insufficient 

 evidence, as witness Michelet's statement that the 

 swallow flies at the rate of eighty leagues an hour. 

 Roughly this gives us a thousand miles in four 

 hours ; but assuredly, even in its dashes, the swallow 

 does not attain to anything like this speed. The 

 Duke of Argyll is rather under than over the mark 

 when he computes the speed at more than a hundred 

 miles an hour. Here, however, the mechanism of 

 flight in the swallows is carried through an ascending 

 scale, until in the swift it reaches its highest degree 

 of power, both in endurance and facility of evolution. 



