<P> Franklin asked Timothy Folger, his cousin twice removed (Nantucket Historical Society), a Nantucket Island whaling captain, for an answer . Folger explained that merchant ships routinely crossed the then - unnamed Gulf Stream--identifying it by whale behavior, measurement of the water's temperature and the speed of bubbles on its surface, and changes in the water's color--while the mail packet captains ran against it . Franklin worked with Folger and other experienced ship captains, learning enough to chart the Gulf Stream and giving it the name by which it is still known today . He offered this information to Anthony Todd, secretary of the British Post Office, but it was ignored by British sea captains . </P> <P> Franklin's Gulf Stream chart was published in 1770 in England, where it was mostly ignored . Subsequent versions were printed in France in 1778 and the U.S. in 1786 . </P> <P> The Gulf Stream proper is a western - intensified current, driven largely by wind stress . The North Atlantic Drift, in contrast, is largely thermohaline circulation--driven . In 1958 the oceanographer Henry Stommel noted that "very little water from the Gulf of Mexico is actually in the Stream". By carrying warm water northeast across the Atlantic, it makes Western and especially Northern Europe warmer than it otherwise would be . </P> <P> However, the extent of its contribution to the actual temperature differential between North America and Europe is a matter of dispute, as there is a recent minority opinion within the science community that this temperature difference (beyond that caused by contrasting maritime and continental climates) is mainly due to atmospheric waves created by the Rocky Mountains . </P>

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