F. W. HEADLEY: WIND AND FLIGHT. 173 



had an upward incline and which blew from hehind him. 

 From which we may infer that, provided that the wind 

 has the required upward slant, the soaring- Eagle may be 

 lifted by it whether it blows from in front or behind him, 

 he may maintain his level and even gain altitude during- 

 the whole of each round of the spiral. 



In conclusion I wish to notice two minor jDoints. No 

 small birds soar. A very curious point this, of which I 

 have never seen any good exiDlanation. Their wings, in 

 proportion to the weight they have to carry, are larger 

 than those of larger birds. But though larger in jJro- 

 portion to the weight to be carried, they are, of course, 

 actually smaller. They are so small that when they are 

 held rigidly expanded, the air escapes past their edges 

 without giving- much su23port. Moreover, big birds have 

 at the armpit an umbrella-like concavity which must act 

 as a fine 2)aTachute, The small narrow wing- is effective 

 only when moved with lightning rapidity. The other 

 small j)oint is this. The soaring birds spread their great 

 flight feathers like fingers, so that daylight can easily be 

 seen between. If the edg-e of the wino- formed an un- 

 broken straight line, the air would be likel}^ to escape 

 suddenly and en masse from beneath it, and make balancing- 

 difficult. It was to obviate this same difficulty that Mr. 

 Pilclier had a number of small holes made in the enormous 

 wings by the aid of which he floated through the air. 



