OCEAN TEMPERATURES AND CURRENTS. 



235 



Taking up the velocity, first let us compare it with 

 that of some of our best known rivers. Three to five 

 miles per hour means about 5 to 10 ft. per second. The 

 flow of the Rhine at Manheim is about 5 ft. per second, 

 that of the Danube at Vienna is about 6 ft. per second, 

 and the same is true for the Mississippi between the 

 Ohio and the Arkansas. Such contrasts give a much 

 clearer idea of its velocity than a mere statement of the 

 figures. 



We notice next that the velocity decreases. This 

 "river in the ocean" is subject to the same laws of 

 friction which control the flow of all rivers, and conse- 

 quently is slowly retarded in its onward progress by con- 

 tact with the water at the sides and on the bottom of 

 the current. This frictional element becomes greater 

 from the fact that, as the current proceeds, the warm 

 water has a tendency to rise to the surface in spite of 

 its velocity, and as it spreads out, the frictional surfaces 

 are naturally increased. When the velocity has consid- 

 erably decreased, this friction seems to break up the 

 stream into numerous bands which separate and pass 



