INFLUENCE OF THE GULF STREAM UPON COMMERCE. 63 



96. The influence of the Gulf Stream ujjon commerce and 

 navigation, 



Formerlj the Gulf Stream controlled commerce across the At- 

 lantic by governing vessels in their routes through this ocean to 

 a greater extent than it does now, and simply for the reason that 

 ships are faster, nautical instruments better, and navigators are 

 more skillful now than formerly they were. 



97. Up to the close of the last century, the navigator guessed 

 as much as he calculated the place of his ship : vessels from Eu- 

 rope to Boston frequently made Xew York, and thought the land- 

 fall by no means bad. Chronometers, now so accurate, were then 

 an experiment. The iSTautical Ephemeris itself was faulty, and 

 gave tables which involved errors of thirty miles in the longitude. 

 The instruments of navigation erred by degrees quite as much as 

 they now do by minutes ; for the rude "cross staff" and "back 

 staff," the "sea-ring" and "mariner's bow," had not yet given 

 place to the nicer sextant and circle of reflection of the present 

 day. Instances are numerous of vessels navigating the Atlantic 

 in those times being 6°, 8°, and even 10° of longitude out of their 

 reckoning in as many days from port. 



98. Though navigators had been in the habit of crossing and 

 recrossing the Gulf Stream 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. 



99. 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 warm and the cool waters was 

 sharp (§ 2) ; and this dividing line, especially that on the western 

 side of the stream, never changed its position as much in longitude 

 as mariners erred in their reckoning. 



100. When he was in London in 1770, he happened to be con- 

 sulted as to a memorial w^hich the Board of Customs at Boston 

 sent to the Lords of the Treasury, stating that the Falmouth pack- 

 ets were generally a fortnight longer to Boston than common trad- 

 ers were from London to Providence, Ehode Island. They there- 



