Historical Inteoduction 9 



to occupy the section from Fowey Rocks to Gun Cay, ' the time actually 

 employed in observations at Section A being over 1,100 hours'. Obser- 

 vations were also made at four other sections across the Florida Straits, 

 at a station off Cape Hatteras, and at a number of stations in the passages 

 of the Windward Islands, 



Pillsbury noted the westward intensification of streamlines Avithin the 

 Straits themselves, as earUer reported by Fremont. By sounding across 

 the Gulf Stream all the way from the Straits to Cape Hatteras and showing 

 that the bottom in this region was comparatively smooth, he disproved 

 Bache's hypothesis that mountain ranges under the sea cause ' bands ' of 

 cold water. His observations of temperature and current in the Florida 

 Straits are unique and are so valuable that they are still used (Wiist, 1924) 

 as the classical example of the accuracy of the geostrophic current deter- 

 mination. He was a firm behever in the theory of wind-driven ocean 

 currents. He felt that the time variations of temperature, horizontally 

 and vertically, along the Gulf Stream were abundantly proved, and he 

 attributed them to random local winds and tidal influences along the 

 coast. He estabHshed that the Antilles Current is a tributary to the Gulf 

 Stream. He emphasized the importance of the prevailing westerUes in 

 maintaining the North Atlantic Drift. He surmised that the Stream 

 becomes increasingly meandering as it flows northeastward. 



During the 1870's there was a good deal of discussion on a quaUtative 

 plane between adherents and antagonists of the wind theory. The reader 

 can form a fair idea of the level at which these discussions were carried on 

 by reading the views of Aitken (1877), Carpenter (1874), and Sir C. Wyville 

 Thomson (1874). A mathematical physicist, Zoppritz (1878), attempted to 

 show that the wind stress could cause appreciable ocean currents only after 

 hundreds of thousands of years of constantly acting upon the water, 

 because the molecular viscosity of water is so small. The importance of the 

 role of turbulence in the ocean as an agency in the transfer of momentum, 

 as well as of other properties, was not at that time appreciated. In 1883, 

 five years after the work by Zoppritz, Rejmolds' famous paper on his 

 experiments on turbulent flow in pipes appeared. The reahzation of the 

 fact that the ocean is essentially a turbulent regime showed the error in 

 Zoppritz' reasoning. 



It is important to realize that thus far in the nineteenth century the 

 influence of the earth's rotation upon ocean currents was only imperfectly 

 understood by oceanographers, although the hydrodjniamical equations of 

 a perfect barotropic fluid relative to a rotating sphere had been written 

 down in the previous century by Laplace (1778). The extremely important 

 fact that the Coriolis force is almost everywhere balanced by the horizontal 

 pressure gradients associated with the distribution of mass was not realized, 



