GULF STREAM, CLIMATES, AND COMMERCE. 69 



almost daily for three centuries, it never occurred to them to 

 make use of it as a means of giving them their longitude, and of 

 warning them of their approach to the shores of this continent. 

 Dr. Franklin was the first to suggest this use of it. The contrast 

 afforded by the temperature of its waters and that of the sea 

 between the Stream and the shores of America was striking. 

 The dividing line between the wann and the cool waters was 

 sharp (§ 70); and this dividing line, especially that on the 

 western side of the stream, seldom changed its position as much 

 in longitude as mariners often erred in their reckoning. 



183. Folgers Chart. — When he was in London, in 1770, he 

 happened to be consulted as to a memorial which the Board of 

 Customs at Boston sent to the Lords of the Treasury, stating that 

 the Falmouth Packets were generally a fortnight longer to Boston 

 than common traders were from London to Providence, Ehode 

 Island. They therefore asked that the Falmouth packets might 

 be sent to Providence instead of to Boston. This appeared 

 strange to the doctor, for London was much farther than Fal- 

 mouth, and from Falmouth the routes were the same, and the 

 difference should have been the other way. He, however, con- 

 sulted Captain Folger, a Kantucket whaler, who chanced to be in 

 London also; the old fisherman explained to the philosopher 

 that the difference arose from the circumstance that the Ehode 

 Island captains were acquainted with the Gulf Stream, while 

 those of the English packets were not. The latter kept in it, 

 and were set back sixty or seventy miles a day, while the former 

 avoided it altogether. He had been made acquainted with it by 

 the w^hales which were found on either side of it, but never in 

 it (§ 158). At the request of the doctor, he there traced on a 

 chart the course of this stream from the Straits of Florida. The 

 doctor had it engraved at Tower Hill, and sent copies of it to 

 the Falmouth captains, who paid no attention to it. The course 

 of the Gulf Stream as laid down by that fisherman from his 

 general recollection of it, has been retained and quoted on the 

 charts for navigation, we may say, until the present day. But the 

 investigations of which we are treating are beginning to throw 

 more light upon this subject ; they are giving us more correct 

 knowledge in every respect with regard to it, and to many other 

 new and striking features in the physical geography of the sea. 



184. Using the Gulf Stream in winter. — Iso part of the world 

 affords a more difficult or dangerous navigation than the ap- 

 proaches of the jSorth American coast in winter. Before tiie 



