TROPICAL SEA-BIRDS 303 



great luminary disappears, animal creation becomes mute, and 

 the voices of the air and ocean are again the only sounds which 

 j break the silence of the arctic night. 



The crystal mass floats along, buried in deep darkness ; but 



soon a new and wondrous sight is seen, for the flaming swords 



! of the northern light flit through the heavens, casting a magic 



I gleam, here on the desert shore, there on the dark bosom of 



the sea. 



Advancing farther and farther to the south, the iceberg loses 

 one after another the witnesses of its first migrations, and 

 wasting more and more, at length entirely merges in the tepid 

 Gulf-stream. The enthralled waters are now all liberated, 

 but many on their western passage are again diverted to the 

 north, and the others reach, only after a long circuit, the 

 mighty equatorial stream, which carries them along, through 

 the torrid ocean, from one hemisphere to the other. 



The animal life they meet with in these sunny regions is very 



Sperm Whale. 



diff'erent from that which witnessed their passage through the 

 higher latitudes. 



The large whalebone whale, the rorqual and narwhal of the 

 north, have disappeared, but pods of the mighty sperm whale 

 rapidly traverse the equatorial seas. 



The birds also exhibit new types of being. The royal alba- 

 tross avoids the torrid zone, but the high-soaring frigate-bird 

 hovers over the waters, where it is seen darting upon the 

 flying-fish, and like the skua gull of the north, attacking 



