Chapter XIX 

 OUR SALT-WATER WORLD 



Every schoolboy knows, as Macaulay would say, 

 that the ocean Is one continuous sheet of water covering 

 more than three fifths of the whole surface of the earth. 

 And although no part of it is separated from the rest, 

 the intervening land areas mark it off in five great 

 divisions known as the Atlantic, Pacific, Indian, Arctic, 

 and Antarctic oceans. But of the general characters 

 and conditions of the sea, none of us is too highly 

 aware. So our final inquiry will be directed not so much 

 toward the geographical aspects of that great realm 

 whose inhabitants have occupied the major portion of 

 this work, but rather toward some of the physical and 

 closely related aspects of the element in which they live. 



Oceanography, or the science of the sea, is a com- 

 Daratively recent development. When scientific inves- 

 tigation of the sea began we were obliged to get most 

 of our information from conditions prevailing near the 

 shore or from mariners whose reports of conditions far 

 from land were generally colored with marvelous or 

 frightful accounts. But WMth the later rapid increase 

 in the study of the exact sciences came the development 

 and invention of accurate instruments; and with the aid 

 of these, observations are now easy and common. Even 



318 



