NATURE OF THE STREAM 147 



Near the headwaters of the Gulf Stream, in the Florida 

 Straits, a new attack is being made. Here the emphasis is on 

 the day-by-day changes in the pulse of the Ocean River. It 

 has already been mentioned that currents may be measured 

 by the uphill slope across the flow, and for this purpose tide 

 stations at Miami and Cat Cay are being operated by the 

 U. S. Coast and Geodetic Survey and by the Miami Marine 

 Laboratory for the continuous information they give about 

 sea level. The Hydrographic Office of the Cuban Navy is 

 also co-operating in a careful accounting of the waters that 

 enter and leave the main course, and the detailed structure 

 of the current is being recorded by the pen of the GEK as its 

 electrodes are towed across the Straits. And here the current 

 has already shown itself to be not a simple steady flow but a 

 turbulent torrent, where fast- and slow-moving bands of water 

 alternate across its width. 



With such intensive interest in the Atlantic circulation as 

 there is today the future may bring new understanding of 

 the rhythm of its pulse and of the effects that this rhythm 

 has on the movement of ice in the North Atlantic, on the 

 yield of great commercial fisheries, and on the climate and 

 weather of many places. But this forms a later part of 

 our story. 



Enough has been said to give some idea of the circulation 

 of the greatest river in the world, with its headwaters in the 

 Gulf of Mexico, its course the entire North Atlantic. The 

 great wind engine that drives it and the deep slow massive 

 flows of cold water that keep the whole in equilibrium have 

 been studied by oceanographers and meteorologists, so that 

 we now have some idea of the machinery that operates it. 

 But the wind engine has a tale of its own, for it is through the 

 air above us that the energy of the sun is dispensed to bring 

 movement to the oceans and life to the creatures within and 

 around them. 



