248 THE HAUNTS OF LIFE 



see a marvellous thing, but the marvel in- 

 creases when in front of us the bird tilts its 

 body and turns, and comes towards us down the 

 other side of the ship, and all, so far as we can 

 see, without a stroke of its wings. This sailing 

 is, we think, the most wonderful locomotion in 

 the world, and the puzzle of it does not seem to 

 have been altogether solved. It is finely 

 illustrated by vultures " soaring" in mid-air, 

 describing circle after circle, ascending in a 

 magnificent spiral and sailing down again, and 

 all, so far as the field-glass shows, without any 

 stroke of the wings. The word " soaring " is 

 often applied to this mysterious kind of flight, 

 but, "sailing" is a better word. It is better to 

 keep "soaring " for the ascending flight of the 

 lark, where there is very rapid up-and-down 

 movement of the wings, without any backward 

 stroke. This leads on to the "hovering" of 

 the kestrel, where the up-and-down movements 

 of the wings are extraordinarily rapid, and to 

 the "fluttering" of a humming-bird, poised 

 like a moth before a flower. But sailing is a 

 different matter. 



Sailing is seen in birds with a large wing-area 

 or sail-area in proportion to the size and weight 

 of the rest of the body, e.g. albatross, vulture, 



