4 Historical Introduction 



in circumference. Ships which once enter one of these channels 

 never return, not even -with the most favourable ^\dnds, and next 

 to the Black Rock all the water is engulfed into the bowels of the 

 earth, whence it flows through springs and river sources once 

 again into the light of day. [Translation.] 



From the Louisiane in 1702 Laval observed what he thought were 

 variations in the strength of the Florida Current associated with the north 

 component of wind ; and in his book about the voyage pubHshed some 

 years later (1728), he stated that he believed this phenomenon to be 

 common knowledge among sailors. 



THE PERIOD 1700-1850 



During the early 1700's the great American whale fishery sent ships all 

 over the world, and the names of such patches of sand as Nantucket be- 

 came knoAvn in every land touching the sea. The practical knowledge 

 gained by these seafarers was not ^\ddely pubhshed in technical journals; 

 instead, it was handed do%Mi by a system of apprenticeship and by word of 

 mouth. And meanwhile, the basic understanding of fluid mechanics was 

 growing. Daniel BernoulU's Hydrodynamica was pubhshed in 1738. In the 

 last third of the century the study of the theoretical aspects of oceanic 

 tides was brought to a high point in the contributions of Laplace. The 

 influence of these developments in theoretical mechanics, and the general 

 intellectual atmosphere of this Age of Enhghtenment, discouraged further 

 extraphysical and purely imaginative theories of ocean currents. 



In 1770 the Board of Customs at Boston complained to the Lords of the 

 Treasury at London that the mail packets usually required two weeks 

 longer to make the trip from England to New England than did the 

 merchant ships. Benjamin Franklin was Postmaster General at the time 

 and happened to discuss the matter Avith a Nantucket sea captain, Timothy 

 Folger. The captain said he beheved that charge to be true (FrankHn, 

 1786, p. 314): 



*^We are well acquainted with the stream because in our pursuit 

 of whales, which keep to the sides of it but are not met within it, 

 we run along the side and frequently cross it to change our side, 

 and in crossing it have sometimes met and spoke with those 

 packets who were in the middle of it and stemming it. We have 

 informed them that they were stemming a current that was 

 against them to the value of three miles an hour and advised them 

 to cross it, but they were too wise to be councelled \sic\ by simple 

 American fishermen.' 



