140 National Geographic Magazine. 



traordinary variety of animal life, previously unknown to science. 

 Few vessels have furnished a greater number of deep-sea sound- 

 ings than the F. C. S. Albatross. This steamer has explored 

 fishing grounds on the east and west coasts of the continent ; 

 and since the beginning of last year has made a cruise from the 

 North to the South Atlantic along the east coast of South Amer- 

 ica, through Magellan Strait, and northward along the west coast 

 to Panama and the Galapagos Islands, ^nd thence to San Fran- 

 cisco and Alaska ; the scenes of her latest operations have been 

 the plateau between the Alaskan coast and TJnalaska and the 

 banks off San Diego, California. 



A large share in the progressive state of the science of the 

 Geography of the Sea must also be credited to the systematic 

 collection of marine observations by the Hydrographic Offices 

 and other institutions all over the world. This forms the stock 

 from which, as I have already indicated, must be drawn, through 

 intelligent reduction and deduction, a better knowledge of the 

 intricate laws governing the various phenomena of the sea and 

 air. 



Oceanic Cieculation. 



The existence of currents in certain localities was known at a 

 very early date, and navigators in their voyages to the new world 

 soon discovered the Gulf Stream and other currents of the Atlan- 

 tic. The first current charts were published more than two hun- 

 dred years ago. Theories were soon advanced to explain the 

 causes, one group of scientific men attributing the origin of cur- 

 rents to differences of level produced by an unequal distribution 

 of atmospheric pressure over the oceans, another set connecting 

 the tidal phenomena with the cause of ocean currents, and still 

 another finding in the rotation of the earth a sufficient reason for 

 their existence. The polar origin of the cold deep water found 

 in low latitudes has long been considered probable, and has given 

 rise to a theory of a general oceanic circulation in a vertical and 

 horizontal direction, produced by diffei'ences of temperature and 

 density. Recent theoretical investigations, however, seem to in- 

 dicate that these causes alone are incapable of producing cur- 

 rents, and, to-day, the theory that the winds are mainly responsi- 

 ble for all cuj-rent movements very largely predominates. Ben- 

 jamin Franklin was probably the first who recognized in the 

 trade winds the cause of the westerly set in the tropics, and Ren- 



