Ben Franklin's Gulf Stream Weather and Swim Fins

The initial concept of creating Franklin's famous chart of the Gulf Stream was prompted in 1768 when Franklin was in London serving as Deputy Postmaster General for North America (Van Doren, 1938). While in London, Franklin received complaints from America as to how westbound mail packets [English ships] took up to two weeks longer than American merchant ships (5) Am. Philos. Soc. lxxvi (5). (1936). At about the same time, the English postal authorities had written to Franklin asking similar questions (Cohn, 1998; Richardson, 1980). These inquiries from Americans and the English about the speed of ships crossing the Atlantic prompted Franklin to do some research. While researching the answers to these complaints in 1768, Franklin made inquiries of Timothy Folger, who happened to be in London at the time. Folger informed Franklin that based on experience, Nantucket whalers had developed a working knowledge of the Gulf Stream between Europe and America. This knowledge came from the whalers following the migration patterns of whales, which were consistently found north or south beyond the edges of the Gulf Stream, but never inside the Gulf Stream. Whaling captains from Nantucket and Martha's Vineyard knew that whales could be found feeding along the Gulf Streams plankton-rich boundaries. They also had learned that sailing back to New England whaling ports could be achieved in less time by staying north of the Gulf Stream and thereby avoiding its current. Keywords: Ben Franklin's chart; prevailing winds