156 THE REIGN OF LAW. 



they roam are broad, and there are no obstruc- 

 tions in the way. They fly in straight lines, 

 changing their direction only in long curves, and 

 lighting in the sea almost with a tumble and a 

 splash. Their rising again is a work of great 

 effort, and generally they have to eke out the 

 resisting power of their small wings, not only by 

 the most violent exertion, but by rising against 

 the wind, so as to collect its force as a help 

 and addition to their own. 



And now, again, we may see all these conditions 

 changed where there is a change in the purpose 

 to be served. There is another large class of 

 oceanic Birds whose feeding ground is not under 

 water, but on the surface of the sea. In this class 

 all those powers of flight which would be useless 

 to the Divers, are absolutely required, and are 

 given in the highest perfection, by the enlistment 

 of the same mechanical laws under different condi- 

 tions. In the Gulls, the Terns, the Petrels, and in 

 the Fulmars, with the Albatross as their typical 

 Form, the mechanism of flight is carried through an 

 ascending scale, to the highest degrees of power, 

 both as respects endurance and facility of evolution. 



