28 CURRENTS OF THE OCEAN. 



If the currents of the sea were not employed to carry off 

 from this animal the waters that have been emptied by it of 

 their lime, and to bring to it others supplied with more, it is 

 apparent that it would have died for want of something to 

 eat long before its work was completed. But for the benign 

 current, the emptied drop of water would have remained, 

 not only as the grove of the little builder, but as a monu- 

 ment recording a monstrous failure in the beautiful system 

 of terrestial adaptations. 



It may be reasonably concluded that the marine animals, 

 whose secretions are so constituted as to alter the specific 

 gravity of the water, to disturb its equilibrium, to originate 

 currents in the ocean, and to control its circulation, are not 

 in any place nor doing this work by accident. Nature is 

 sublime and perfect in adaptation through all her domain. 



Currents, which exercise so great an influence on the cir- 

 culation of the waters, and in producing remarkable changes 

 in the form of coasts, are described as constant, periodical, 

 and variable ; the two latter classes being determined chiefly 

 by the wi,nds and tides. The first motion of the ocean 

 waves is derived either from the attraction of the sun or 

 moon, or from w4nds which blow over the surface of the 

 waters; the second arises from the sun, which directly 

 through its heat, and indirectly by scorching dry winds, 

 produces evaporation, to a great extent, of the parts most 

 exposed to its influence ; and by its similar action on the 

 atmosphere, causes a transference of this vapor to remote 

 latitudes, where it descends as rain, and by destroying the 

 equilibrium of the ocean, gives rise to currents. The prin- 

 cipal currents of the ocean are four, two warm, and two 

 cold ; these originate, the former among the islands of the 

 Archipelago and in the Gulf of Mexico, and the latter in the 

 Arctic and Southern Oceans. 



The most important and best known of ocean currents, the 

 Gulf Stream — the river in the ocean, one of the most mar- 



