494 LIFE ON THE OCEAN SURFACE. 



on shore regularly, like the Seal, at certain seasons to breed, 

 but at length acquired the power of rearing their young in the 

 open sea. 



Amongst birds the Petrels are pelagic in habit, the largest 

 amongst them being the Albatross. Of the various kinds of 

 Petrels we necessarily saw a great deal. They were our con- 

 stant companions in the Southern Ocean, following the ship 

 day after day, dropping behind at night to roost on the water 

 and tracing the ship up again in the early morning by the 

 trail of debris left in its wake. 



The Oceanic Petrels have reduced the science of flight to 

 the condition of a fine art. The flight of the Albatross has 

 always excited wonder and admiration ; nevertheless, some of 

 the smaller Petrels fly quite as well. There are almost all 

 gradations to be observed in the powers of flight of different 

 birds, in the various stages of perfection in the shaping of the 

 wings, and the skill in the use of them shown by the birds. 

 Refinement in the art of the use of the wings by birds seems to 

 run in two different directions. The flight of the Albatross, 

 regarded as the perfection of one mode, the soaring method, 

 performed by aid of great length of wing, may be contrasted 

 with that of the Humming Bird, equally perfect in its way and 

 far more rapid, but performed by the use of short wmgs and 

 excessively rapid motion of them. 



The movement of the Albatross may be compared to that 

 of a skilful skater on the outside edge ; the Humming Bird's 

 flight is just like that of an insect. The Albatross ekes out to 

 the utmost the momentum derived from a few powerful strokes, 

 and uses it up slowly in gliding, making all possible use at the 

 same time of the force of the wind. 



I believe that Albatrosses move their wings much oftener 

 than is suspected. They often have the appearance of soaring 

 for long periods after a ship without flapping their wings at all, 

 but if they be very closely watched, very short but extremely 

 quick motions of the wings may be detected. The appearance 

 is rather as if the body of the bird dropped a very short dis- 

 tance and rose again. The movements cannot be seen at all 

 unless the bird is exactly on a level with the eye. A very 

 quick stroke, carried even through a very short arc, can of 

 course supply a large store of fresh momentum. In perfectly 

 calm weather. Albatrosses flap heavily. 



The Great White Albatrosses which are seen behind ships 

 are usually by no means beautiful objects. The long wings 

 look far too long for the body, and being so narrow, the body 

 looks heavy and out of proportion to them. Further, five out 

 of six of the birds seen are young ones, in immature brown 



