140 THE OCEAN RIVER 



up their secrets to the persistent curiosity of oceanographers, 

 meteorologists continued their inquiries into the prime causes 

 of the great surface flow, and as a result the long-continued 

 arguments between adherents of the density theory and of the 

 wind theory are now fairly well resolved. There is little doubt 

 today that the density of sea water, its varying heat and cold 

 and saltness, is a reservoir of solar energy for the rise and fall 

 of water and the slow massive movements deep below the 

 surface. The work of Ekman and others has made it equally 

 certain that the great circular sweep of the surface currents 

 has for its engine the whole Atlantic wind system — the trade 

 winds driving the Equatorial and Caribbean Currents and 

 the westerly winds of the northern part giving movement to 

 the North Atlantic Drift. Today attention is focused on cer- 

 tain other mysteries of the Gulf Stream. 



During the past twenty years the major attack on the Gulf 

 Stream has been by scientists from the Woods Hole Oceano- 

 graphic Institution, which was partly founded for this very 

 purpose. Under the leadership of Columbus O'D. Iselin, a 

 team of scientists has collaborated with other scientific insti- 

 tutions to bring new light to bear on a number of difficult 

 problems. From observations made at sea aboard the Diesel- 

 engined ketch Atlantis, it was found that water is added to the 

 Stream along its right-hand edge and an equivalent amount 

 is thrown out intermittently along the western border in the 

 form of eddies. This sideways transport of water across the 

 Gulf Stream has been explained by the mathematical analysis 

 of Carl-Gustaf Rossby, who regards the Current as a wake 

 stream or jet flow forced out of the Straits of Florida into the 

 Atlantic Ocean. He has shown that a necessary characteristic 

 of this kind of stream is that eddies should be formed at the 

 left side while water is drawn in from the right. 



Another feature that seems to be characteristic of the water 

 circulation of all oceans is that in the western part the current 



