CHARTING THE RIVER 119 



greatly aided navigators in determining exact positions, and 

 thus helped in the accurate plotting of the direction and 

 strength of currents. With their aid the charting of the Ocean 

 River became more of a science and less an affair of general 

 observation, imagination, and intuition. And so since the time 

 of Franklin the rest of our story is that of the steady growth of 

 ocean science, and the discovery of not merely where, but also 

 why and how fast these salt rivers move in the salt ocean. 



